V. Coker, J. A. Bennett, N. Telling et al.

ACS Nano • 2010

Precious metals supported on ferrimagnetic particles have a diverse range of uses in catalysis. However, fabrication using synthetic methods results in potentially high environmental and economic costs. Here we show a novel biotechnological route for the synthesis of a heterogeneous catalyst consisting of reactive palladium nanoparticles arrayed on a nanoscale biomagnetite support. The magnetic support was synthesized at ambient temperature by the Fe(III)-reducing bacterium, Geobacter sulfurreducens , and facilitated ease of recovery of the catalyst with superior performance due to reduced agglomeration (versus conventional colloidal Pd nanoparticles). Surface arrays of palladium nanoparticles were deposited on the nanomagnetite using a simple one-step method without the need to modify the biomineral surface, most likely due to an organic coating priming the surface for Pd adsorption, which was produced by the bacterial culture during the formation of the nanoparticles. A combination of EXAFS and XPS showed the Pd nanoparticles on the magnetite to be predominantly metallic in nature. The Pd(0)-biomagnetite was tested for catalytic activity in the Heck reaction coupling iodobenzene to ethyl acrylate or styrene. Rates of reaction were equal to or superior to those obtained with an equimolar amount of a commercial colloidal palladium catalyst, and near complete conversion to ethyl cinnamate or stilbene was achieved within 90 and 180 min, respectively.

Yiyan Song, Hui-jun Jiang, Bangbang Wang et al.

ACS Applied Materials & Interfaces • 2018

To tackle severe environmental pollution, a search for materials by economical and eco-friendly preparations is demanding for public health. In this study, a novel in situ method to form silver nanoparticles under mild conditions was developed using biomimetic reducing agents of polydopamine coated on the rodlike mesoporous silica of SBA-15. The synthesized SBA-15/polydopamine (PDA)/Ag nanocomposites were characterized by a combination of physicochemical and electrochemical methods. 4-Nitrophenol (4-NP) and methylene blue (MB) were used as models for the evaluation of the prepared nanocatalysts of SBA-15/PDA/Ag in which the composite exhibited enhanced catalytic performance toward degrading 4-NP in solution and MB on the membrane, respectively. Additionally, compared with that of solid core-shell SiO2/PDA/Ag, tubular SBA-15/PDA/Ag showed the prolonged inhibitory effect on microbial growth as typified by Escherichia coli (60 h), Staphylococcus aureus (36 h), and Aspergillus fumigatus (60 h), which demonstrated efficient control of silver nanoparticles release from the mesopores. The constructed dual-functional SBA-15/PDA/Ag as the long-term antimicrobial agent and the catalyst of industrial products provides an integrated nanoplatform to deal with environmental concerns.

Sagar Vikal, Y. K. Gautam, Swati Meena et al.

Nanoscale Advances • 2023

The different dyes used and discharged in industrial settings and microbial pathogenic issues have raised serious concerns about the content of bodies of water and the impact that dyes and microbes have on the environment and human health. Efficient treatment of contaminated water is thus a major challenge that is of great interest to researchers around the world. In the present work, we have fabricated functionalized silver-doped ZnO nanoparticles (Ag-doped ZnO NPs) via a hydrothermal method for wastewater treatment. X-ray photoelectron spectroscopy analysis confirmed the doping of Ag with ZnO NPs, and X-ray diffractometry analysis showed a decreasing trend in the crystallite size of the synthesized ZnO NPs with increased Ag concentration. Field emission scanning electron microscopy study of pure ZnO NPs and Ag-doped ZnO NPs revealed nanocrystal aggregates with mixed morphologies, such as hexagonal and rod-shaped structures. Distribution of Ag on the ZnO lattice is confirmed by high-resolution transmission electron microscopy analysis. ZnO NPs with 4 wt% Ag doping showed a maximum degradation of ∼95% in 1.5 h of malachite green dye (80 mg L−1) under visible light and ∼85% in 4 h under dark conditions. Up to five successive treatment cycles using the 4 wt% Ag-doped ZnO NP nanocatalyst confirmed its reusability, as it was still capable of degrading ∼86% and 82% of the dye under visible light and dark conditions, respectively. This limits the risk of nanotoxicity and aids the cost-effectiveness of the overall treatment process. The synthesized NPs showed antibacterial activity in a dose-dependent manner. The zone of inhibition of the Ag-doped ZnO NPs was higher than that of the pure ZnO NPs for all doping content. The studied Ag-doped ZnO NPs thus offer a significant eco-friendly route for the effective treatment of water contaminated with synthetic dyes and fecal bacterial load.

Sherif Elbasuney, A. M. El-Khawaga, M. A. Elsayed et al.

Scientific Reports • 2023

Hydroxyapatite (HA), the most common bioceramic material, offers attractive properties as a catalyst support. Highly crystalline mono-dispersed silver doped hydroxyapatite (Ag-HA) nanorods of 60 nm length was developed via hydrothermal processing. Silver dopant offered enhanced chemisorption for crystal violet (CV) contaminant. Silver was found to intensify negative charge on the catalyst surface; in this regard enhanced chemisorption of positively charged contaminants was accomplished. Silver dopant experienced decrease in the binding energy of valence electron for oxygen, calcium, and phosphorous using X-ray photoelectron spectroscopy XPS/ESCA; this finding could promote electron–hole generation and light absorption. Removal efficiency of Ag-HA nanocomposite for CV reached 88% after the synergistic effect with 1.0 mM H_2O_2; silver dopant could initiate H_2O_2 cleavage and intensify the release of active ȮH radicals. Whereas HA suffers from lack of microbial resistance; Ag-HA nanocomposite demonstrated high activity against Gram-positive ( S. aureus ) bacteria with zone of inhibition (ZOI) mm value of 18.0 mm , and high biofilm inhibition of 91.1%. Ag-HA nanocompsite experienced distinctive characerisitcs for utilization as green bioceramic photocatalyst for wastewater treatment.

Eréndira Garza-Duran, Gregorio Vargas-Gutiérrez, Beatriz Escobar-Morales et al.

ECS Meeting Abstracts • 2019

<jats:p> Microbial Fuel Cells (MFCs) are bio-electrochemical systems that use bacteria to generate bioelectricity via the oxidation of organic matter contained in a substrate (such as wastewater). However, this new method of renewable energy recovery has several technical challenges. At the cathode, for example, the Oxygen Reduction Reaction (ORR) takes place. This reaction is kinetically slow, remaining one of the main drawbacks of MFCs. Even though Pt/C nanocatalysts are widely used to promote the ORR, their performance in MFC is low due to the complex operating conditions. Therefore, alternative cathode nanocatalysts must be developed. Regarding to this issue, core-shell nanocatalysts are a promising alternative for MFCs cathodes. </jats:p> <jats:p>In this study, Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt core-shell nanoparticles have been supported on N-doped and functionalized graphene (N-Gf) to obtain the Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt/N-Gf nanocatalyst. First, nitrogen-doped graphene (N-G) has been synthesized by a one-step ball milling process using graphite as carbon source and melamine as both exfoliating agent and nitrogen source. Then, N-G has been functionalized by a mild acid treatment and labeled as N-Gf. Separately, the Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> core has been obtained by co-precipitation reaction of Fe<jats:sup>2+</jats:sup>/Fe<jats:sup>3+</jats:sup>, using citric acid as surfactant. The Pt shell has been deposited on the core by the Bromide Anion Exchange (BAE) method, resulting in a Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt nanostructure having a 1:1 Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>:Pt molar ratio. The 20 wt.% Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt/N-Gf core-shell nanocatalyst has been obtained also by the BAE method. </jats:p> <jats:p>Regarding N-Gf, its X-ray diffraction (XRD) pattern shows well-defined peaks at 2θ=26.5°, 44.39 and 54.4°, characteristic of graphitic structures. Moreover, its I<jats:sub>D</jats:sub>/I<jats:sub>G</jats:sub> intensity ratio calculated from Raman spectra is 1.40, which indicates a high degree of disorder in the carbon lattice, most likely due to the incorporation of N species into the structure. Additionally, an N content of 1.40 at. % has been determined by energy-dispersive X-ray spectroscopy (EDS). The XRD pattern of the magnetite phase shows reflections at 2θ= 30.44, 35.53, 43.46, 54.01, 57.79, 63.06 and 74.75°, attributed to the (220), (311), (400), (422), (511) (440) and (531) planes. The crystallite size of Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> has been calculated as 9.2 nm. In addition, its Raman spectrum shows signals corresponding to the A<jats:sub>1g</jats:sub>, E<jats:sub>g</jats:sub> and T<jats:sub>2g</jats:sub> vibrational modes, characteristic of magnetite. </jats:p> <jats:p>Meanwhile, the catalytic activity of the Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt/N-Gf nanocatalyst for the ORR has been evaluated by the Rotating Ring-Disk Electrode (RRDE) technique in 0.5 M H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> and in H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> having a pH=6.1. The latter is because of the pH of the pharmaceutical residual water used as substrate in the MFC. Electrochemical parameters such as hydrogen peroxide percentage, number of electrons transferred, and onset and half wave potentials has been determined. The results show that Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt/N-Gf has a catalytic activity for the ORR in low and almost neutral pH comparable to that of a commercial Pt/C nanocatalyst. Therefore, these results suggest that Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>@Pt/N-Gf is a promising cathode nanocatalyst for MFC applications. To the best of the authors knowledge, this is the first time that such nanostructures have been evaluated in MFCs. </jats:p>

Enayatollah Sheikhhosseini, Mahdieh Yahyazadehfar

Frontiers in Chemistry • 0

<jats:p>In this study, the recyclable heterogeneous cluster bud Fe-MOF@Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> ‘nanoflower’ composite (CB Fe-MOF@Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> NFC) was successfully synthesized using Fe(NO<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub>·9H<jats:sub>2</jats:sub>O, 8-hydroxyquinoline sulfate monohydrate, and Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> nanoparticles by microwave irradiation. The as-prepared CB Fe-MOF@Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> NFC was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrational sampling magnetometry (VSM), and Fourier transform infrared spectroscopy (FTIR). The CB Fe-MOF@Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> NFC samples proved to have excellent catalytic activity. The activity of the CB Fe-MOF@Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> NFC nanocatalyst was explored in the synthesis of dihydropyrano[3, 2-c]chromene derivatives via a three-component reaction of 4-hydroxycoumarin, malononitrile, and a wide range of aromatic aldehyde compounds. Optimized reaction conditions had several advantages, including the use of water as a green solvent, environmental compatibility, simple work-up, reusability of the catalyst, low catalyst loading, faster reaction time, and higher yields.</jats:p>

M. Maruthupandy, Muthusamy Anand, Govindhan Maduraiveeran et al.

Advances in Natural Sciences: Nanoscience and Nanotechnology • 2015

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

Yan-Zhai Wang, Yu Shen, Lu Gao et al.

RSC Advances • 2017

Direct electricity production from biomass hydrolysate by microbial fuel cells (MFC) holds great promise for the development of the sustainable biomass industry. Shewanella oneidensis MR-1 is one of the most extensively studied model exoelectrogens in MFC. But it is still unclear whether this model strain could generate bioelectricity from biomass or not. Here, a biomass hydrolysate MFC was constructed by using S. oneidensis MR-1 and electricity output was obtained from corn straw hydrolysate. More impressively, by promoting the extracellular electron transfer efficiency with electron shuttle addition and electrode modification using the vertically aligned polyaniline (PANI) nanowire array, the electricity output from biomass hydrolystate by S. oneidensis MR-1 was greatly improved and a high energy output was obtained, i.e., ∼1260 mA m−2 current output (∼7-fold increase over that of the control) and ∼660 mW m−2 power output (∼37-fold increase over that of the control) were achieved. This work demonstrates that S. oneidensis MR-1 has great potential in electrical energy harvesting from biomass hydrolysate, which broadens the fuel spectrum of the model exoelectrogen (S. oneidensis MR-1) inoculated MFC and also provides a new opportunity for the biomass industry.

Yin Ye, Xing Liu, K. Nealson et al.

mBio • 2022

The low power generation of microbial fuel cells limits their utility. Many factors can affect power generation, including inefficient electron transfer in the anode biofilm. ABSTRACT Conductive nanowires are thought to contribute to long-range electron transfer (LET) in Geobacter sulfurreducens anode biofilms. Three types of nanowires have been identified: pili, OmcS, and OmcZ. Previous studies highlighted their conductive function in anode biofilms, yet a structural function also has to be considered. We present here a comprehensive analysis of the function of nanowires in LET by inhibiting the expression of each nanowire. Meanwhile, flagella with poor conductivity were expressed to recover the structural function but not the conductive function of nanowires in the corresponding nanowire mutant strain. The results demonstrated that pili played a structural but not a conductive function in supporting biofilm formation. In contrast, the OmcS nanowire played a conductive but not a structural function in facilitating electron transfer in the biofilm. The OmcZ nanowire played both a structural and a conductive function to contribute to current generation. Expression of the poorly conductive flagellum was shown to enhance biofilm formation, subsequently increasing current generation. These data support a model in which multiheme cytochromes facilitate long-distance electron transfer in G. sulfurreducens biofilms. Our findings also suggest that the formation of a thicker biofilm, which contributed to a higher current generation by G. sulfurreducens, was confined by the biofilm formation deficiency, and this has applications in microbial electrochemical systems. IMPORTANCE The low power generation of microbial fuel cells limits their utility. Many factors can affect power generation, including inefficient electron transfer in the anode biofilm. Thus, understanding the mechanism(s) of electron transfer provides a pathway for increasing the power density of microbial fuel cells. Geobacter sulfurreducens was shown to form a thick biofilm on the anode. Cells far away from the anode reduce the anode through long-range electron transfer. Based on their conductive properties, three types of nanowires have been hypothesized to directly facilitate long-range electron transfer: pili, OmcS, and OmcZ nanowires. However, their structural contributions to electron transfer in anode biofilm have not been elucidated. Based on studies of mutants lacking one or more of these facilitators, our results support a cytochrome-mediated electron transfer process in Geobacter biofilms and highlight the structural contribution of nanowires in anode biofilm formation, which contributes to biofilm formation and current generation, thereby providing a strategy to increase current generation.

Hanyu Wang, Fang Qian, Gongming Wang et al.

ACS Nano • 2013

Here we demonstrate the feasibility of continuous, self-sustained hydrogen gas production based solely on solar light and biomass (wastewater) recycling, by coupling solar water splitting and microbial electrohydrogenesis in a photoelectrochemical cell-microbial fuel cell (PEC-MFC) hybrid device. The PEC device is composed of a TiO2 nanowire-arrayed photoanode and a Pt cathode. The MFC is an air cathode dual-chamber device, inoculated with either Shewanella oneidensis MR-1 (batch-fed on artificial growth medium) or natural microbial communities (batch-fed on local municipal wastewater). Under light illumination, the TiO2 photoanode provided a photovoltage of ~0.7 V that shifted the potential of the MFC bioanode to overcome the potential barrier for microbial electrohydrogenesis. As a result, under light illumination (AM 1.5G, 100 mW/cm(2)) without external bias, and using wastewater as the energy source, we observed pronounced current generation as well as continuous production of hydrogen gas. The successful demonstration of such a self-biased, sustainable microbial device for hydrogen generation could provide a new solution that can simultaneously address the need of wastewater treatment and the increasing demand for clean energy.

Fang Qian, Hanyu Wang, Yichuan Ling et al.

Nano Letters • 2014

Here we report the investigation of interplay between light, a hematite nanowire-arrayed photoelectrode, and Shewanella oneidensis MR-1 in a solar-assisted microbial photoelectrochemical system (solar MPS). Whole cell electrochemistry and microbial fuel cell (MFC) characterization of Shewanella oneidensis strain MR-1 showed that these cells cultured under (semi)anaerobic conditions expressed substantial c-type cytochrome outer membrane proteins, exhibited well-defined redox peaks, and generated bioelectricity in a MFC device. Cyclic voltammogram studies of hematite nanowire electrodes revealed active electron transfer at the hematite/cell interface. Notably, under a positive bias and light illumination, the hematite electrode immersed in a live cell culture was able to produce 150% more photocurrent than that in the abiotic control of medium or dead culture, suggesting a photoenhanced electrochemical interaction between hematite and Shewanella. The enhanced photocurrent was attributed to the additional redox species associated with MR-1 cells that are more thermodynamically favorable to be oxidized than water. Long-term operation of the hematite solar MPS with light on/off cycles showed stable current generation up to 2 weeks. Fluorescent optical microscope and scanning electron microscope imaging revealed that the top of the hematite nanowire arrays were covered by a biofilm, and iron determination colorimetric assay revealed 11% iron loss after a 10-day operation. To our knowledge, this is the first report on interfacing a photoanode directly with electricigens in a MFC system. Such a system could open up new possibilities in solar-microbial device that can harvest solar energy and recycle biomass simultaneously to treat wastewater, produce electricity, and chemical fuels in a self-sustained manner.

Bo-Lin Song, Zhibin Wang, Lei Wang et al.

ACS Biomaterials Science &amp; Engineering • 2023

The conductive microbial nanowires of Geobacter sulfurreducens serve as a model for long-range extracellular electron transfer (EET), which is considered a revolutionary "green" nanomaterial in the fields of bioelectronics, renewable energy, and bioremediation. However, there is no efficient pathway to induce microorganisms to express a large amount of microbial nanowires. Here, several strategies have been used to successfully induce the expression of microbial nanowires. Microbial nanowire expression was closely related to the concentration of electron acceptors. The microbial nanowire was around 17.02 μm in length, more than 3 times compared to its own length. The graphite electrode was used as an alternative electron acceptor by G. sulfurreducens, which obtained a fast start-up time of 44 h in microbial fuel cells (MFCs). Meanwhile, Fe(III) citrate-coated sugarcane carbon and biochar were prepared to test the applicability of these strategies in the actual microbial community. The unsatisfied EET efficiency between c-type cytochrome and extracellular insoluble electron receptors promoted the expression of microbial nanowires. Hence, microbial nanowires were proposed to be an effective survival strategy for G. sulfurreducens to cope with various environmental stresses. Based on this top-down strategy of artificially constructed microbial environmental stress, this study is of great significance for exploring more efficient methods to induce microbial nanowires expression.

I. Ng, C. Hsueh, Bor-Yann Chen

Bioresources and Bioprocessing • 2017

This review tended to decipher the expression of electron transfer capability (e.g., biofilm formation, electron shuttles, swarming motility, dye decolorization, bioelectricity generation) to microbial fuel cells (MFCs). As mixed culture were known to perform better than pure microbial cultures for optimal expression of electrochemically stable activities to pollutant degradation and bioenergy recycling, Proteus hauseri isolated as a “keystone species” to maintain such ecologically stable potential for power generation in MFCs was characterized. P. hauseri expressed outstanding performance of electron transfer (ET)-associated characteristics [e.g., reductive decolorization (RD) and bioelectricity generation (BG)] for electrochemically steered bioremediation even though it is not a nanowire-generating bacterium. This review tended to uncover taxonomic classification, genetic or genomic characteristics, enzymatic functions, and bioelectricity-generating capabilities of Proteus spp. with perspectives for electrochemical practicability. As a matter of fact, using MFCs as a tool to evaluate ET capabilities, dye decolorizer(s) could clearly express excellent performance of simultaneous bioelectricity generation and reductive decolorization (SBG and RD) due to feedback catalysis of residual decolorized metabolites (DMs) as electron shuttles (ESs). Moreover, the presence of reduced intermediates of nitroaromatics or DMs as ESs could synergistically augment efficiency of reductive decolorization and power generation. With swarming mobility, P. hauseri could own significant biofilm-forming capability to sustain ecologically stable consortia for RD and BG. This mini-review evidently provided lost episodes of great significance about bioenergy-steered applications in myriads of fields (e.g., biodegradation, biorefinery, and electro-fermentation).

Qing Yang, Y. Liu, Zetang Li et al.

Angewandte Chemie International Edition • 2012

An integrated system consisting of a carbon fiber-ZnO hybrid nanowire (NW) multicolor photodetector is driven by a microbial fuel cell (see picture; PMMA = poly(methyl methacrylate), E = electrode). The self-powered photodetector can detect at light levels of as little as nW cm(-2) intensity with a responsivity of more than 300 A W(-1).

Xiaoshuai Wu, Xiaofen Li, Zhuanzhuan Shi et al.

Materials • 2023

The sluggish electron transfer at the interface of microorganisms and an electrode is a bottleneck of increasing the output power density of microbial fuel cells (MFCs). Mo-doped carbon nanofibers (Mo-CNFs) prepared with electrostatic spinning and high-temperature carbonization are used as an anode in MFCs here. Results clearly indicate that Mo2C nanoparticles uniformly anchored on carbon nanowire, and Mo-doped anodes could accelerate the electron transfer rate. The Mo-CNF ΙΙ anode delivered a maximal power density of 1287.38 mW m−2, which was twice that of the unmodified CNFs anode. This fantastic improvement mechanism is attributed to the fact that Mo doped on a unique nanofiber surface could enhance microbial colonization, electrocatalytic activity, and large reaction surface areas, which not only enable direct electron transfer, but also promote flavin-like mediated indirect electron transfer. This work provides new insights into the application of electrospinning technology in MFCs and the preparation of anode materials on a large scale.

Ke Liu, Zhuo Ma, Xinyi Li et al.

Materials • 2023

Microbial fuel cell (MFC) performance is affected by the metabolic activity of bacteria and the extracellular electron transfer (EET) process. The deficiency of nanostructures on macroporous anode obstructs the enrichment of exoelectrogens and the EET. Herein, a N-doped carbon nanowire-modified macroporous carbon foam was prepared and served as an anode in MFCs. The anode has a hierarchical porous structure, which can solve the problem of biofilm blockage, ensure mass transport, favor exoelectrogen enrichment, and enhance the metabolic activity of bacteria. The microscopic morphology, spectroscopy, and electrochemical characterization of the anode confirm that carbon nanowires can penetrate biofilm, decrease charge resistance, and enhance long-distance electron transfer efficiency. In addition, pyrrolic N can effectively reduce the binding energy and electron transfer distance of bacterial outer membrane hemin. With this hierarchical anode, a maximum power density of 5.32 W/m3 was obtained, about 2.5-fold that of bare carbon cloth. The one-dimensional nanomaterial-modified macroporous anodes in this study are a promising strategy to improve the exoelectrogen enrichment and EET for MFCs.

K. Su, X. Yao, S. Sui et al.

Fuel Cells • 2015

<jats:title>Abstract</jats:title><jats:p>The cathode electrocatalyst layers were prepared by <jats:italic>in situ</jats:italic> growing Pt nanowires (Pt‐NWs) in two kinds of matrixes with various Pt loadings for proton exchange membrane fuel cells (PEMFCs). Commercial carbon powder and 20 wt.% Pt/C electrocatalyst were used as the matrix material for the comparison. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), polarization curves tests, and electrochemical impedance spectroscopy (EIS) were carried out to examine the effects of the matrix materials on the Pt‐NW growing and the electrode performance. The optimum Pt‐NW loadings of 0.30 mg cm<jats:sup>−2</jats:sup> in the carbon matrix (CM) and 0.20 mg cm<jats:sup>−2</jats:sup> for the Pt/C matrix (PM) were obtained. The results indicated that the Pt‐NWs grown in the CM had a better crystalline, longer size length and better catalyst activity than those in the PM. The mechanism of the matrix affection is further discussed in this paper. </jats:p>

Alaa Abbas, Mostafa M. Omran, Antonio Marzocchella et al.

ECS Meeting Abstracts • 2025

<jats:p> The depletion of energy resources due to increasing human demands has become a growing concern; thus, developing sustainable energy technologies is essential. One innovative approach is soil microbial fuel cells (SMFCs), which are affordable and carbon-neutral bioremediation energy systems for polluted lands. Carbonaceous materials (CMs) are the most used materials as anodes for SMFCs, as they have reasonable conductivity, biocompatibility, and high surface area. However, decorating the CMs with metal oxide increases their specific surface area, enhancing the electrochemical behavior of the anode and enriching the exoelectrogenic microbial community. Although decorating the anodes with metal oxides, such as Co<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>, MnO<jats:sub>2,</jats:sub> and Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, has enhanced the SMFCs' performance, they suffer instability through metal oxide leakage under operation conditions<jats:sup>1,2</jats:sup>. Thus, more stable metal oxides, such as bimetallic nanostructure oxides, should be investigated as anodes for SMFCs. These oxides are also expected to enhance the electron transfer rate, conductivity, and the exoelectrogenic microbial community.</jats:p> <jats:p>In this work, carbon felt (CF) is decorated with MoCoO<jats:sub>4</jats:sub> nanowires using hydrothermal synthesis. The MoCoO<jats:sub>4</jats:sub> nanowires were then coated with an electropolymerized conductive polymer as a carbon source to achieve better stability and electrical conductivity. The SEM images confirmed the formation of a homogeneous layer of MoCoO<jats:sub>4</jats:sub> nanowires, and the XRD and XPS results demonstrated their crystal structure and chemical composition. A significant improvement in the growth/adhesion of the microbial layer was observed due to the increase in surface area of the roughened electrodes, shown in SEM images, which, in turn, increased the power produced by the SMFC. Accordingly, the SMFC with maximum power was produced using MoCoO<jats:sub>4</jats:sub>@CF anode (87 mW/m<jats:sup>2 </jats:sup> at 178.5 mA/m<jats:sup>2</jats:sup> ), with a power double that produced by the blank GF(44 mW/m<jats:sup>2</jats:sup> at 100 mA/m<jats:sup>2</jats:sup>) and higher than that previously reported in the literature using Cobalt oxide nanoflakes interweaved with polyaniline (70 mW/m<jats:sup>2</jats:sup> at 143 mA/m<jats:sup>2</jats:sup>)<jats:sup>1</jats:sup>. The SMFC that employed MoCoO<jats:sub>4</jats:sub>@CF electrodes maintained high power after fifty days of being in the soil setup, indicating the stability of the nanostructure.</jats:p> <jats:p> <jats:bold>References:</jats:bold> <jats:list list-type="roman-lower"> <jats:list-item> <jats:p>S. K. Dhillon, J. Dziegielowski, P. P. Kundu, and M. D. Lorenzo, <jats:italic>RSC Sustain.</jats:italic>, <jats:bold>1</jats:bold>, 310–325 (2023).</jats:p> </jats:list-item> <jats:list-item> <jats:p>D. Nosek, T. Mikołajczyk, and A. Cydzik-Kwiatkowska, <jats:italic>International Journal of Environmental Research and Public Health</jats:italic>, <jats:bold>20</jats:bold>, 2580 (2023).</jats:p> </jats:list-item> </jats:list> </jats:p>

Mingkai Liu, Peng Zhang, Z. Qu et al.

Nature Communications • 2019

Long-term stability and high-rate capability have been the major challenges of sodium-ion batteries. Layered electroactive materials with mechanically robust, chemically stable, electrically and ironically conductive networks can effectively address these issues. Herein we have successfully directed carbon nanofibers to vertically penetrate through graphene sheets, constructing robust carbon nanofiber interpenetrated graphene architecture. Molybdenum disulfide nanoflakes are then grown in situ alongside the entire framework, yielding molybdenum disulfide@carbon nanofiber interpenetrated graphene structure. In such a design, carbon nanofibers prevent the restacking of graphene sheets and provide ample space between graphene sheets, enabling a strong structure that maintains exceptional mechanical integrity and excellent electrical conductivity. The as-prepared sodium ion battery delivers outstanding electrochemical performance and ultrahigh stability, achieving a remarkable specific capacity of 598 mAh g−1, long-term cycling stability up to 1000 cycles, and an excellent rate performance even at a high current density up to 10 A g−1. Here the authors construct carbon nanofiber interpenetrated graphene architecture with in-situ grown MoS2 nanoflakes alongside the framework. The design combines exceptional mechanical integrity and excellent electronic conductivity, enabling outstanding electrochemical performance in sodium-ion battery.

Jianhao Wang, Yuan Zhao, Xiao-Yi Chen et al.

ACS Nano • 2019

Biofilm infections can induce chronic inflammation and stall normal orchestrated course of wound healing cascades. Herein pH-switchable antimicrobial hydrogel with nanofiber networks for biofilm eradication and rescuing stalled healing in chronic wound is reported based on the self-assembly of a designed octapeptide (IKFQFHFD) at neutral pH. This hydrogel is biocompatible and exhibits acidic pH (pathological environment of infected chronic wounds)-switchable broad-spectrum antimicrobial effect via a mechanism involving cell wall and membrane disruption. The antimicrobial activity of hydrogel is derived from its acidic pH-dependent nanofiber networks destabilization and activated release of IKFQFHFD which is antimicrobial only at acidic pH due to the antimicrobial peptides-like molecular structure. In addition, supramolecular nanofiber networks loaded with drugs of cypate (photothermal agent) and proline (procollagen component) are further developed. In vitro experiments show that loaded drugs exhibit acidic pH (pH ~5.5)-responsive release profiles, and synergistic biofilm eradication and subsequent healing cascades activation of cells proliferation is achieved based on the supramolecular nanofiber networks. Remarkably, the nanofiber networks of hydrogel enables in vivo complete healing of MRSA biofilm-infected wound in diabetic mice within 20 days, showing great potential as promising chronic wound dressings. The proposed synergistic strategy for eradicating biofilm and activating subsequent healing cascades may offer a powerful modality for the management of clinical chronic wounds.

Xiao Peng, Kai Dong, Cuiying Ye et al.

Science Advances • 2020

A breathable, biodegradable, antibacterial, and self-powered skin is developed. Mimicking the comprehensive functions of human sensing via electronic skins (e-skins) is highly interesting for the development of human-machine interactions and artificial intelligences. Some e-skins with high sensitivity and stability were developed; however, little attention is paid to their comfortability, environmental friendliness, and antibacterial activity. Here, we report a breathable, biodegradable, and antibacterial e-skin based on all-nanofiber triboelectric nanogenerators, which is fabricated by sandwiching silver nanowire (Ag NW) between polylactic-co-glycolic acid (PLGA) and polyvinyl alcohol (PVA). With micro-to-nano hierarchical porous structure, the e-skin has high specific surface area for contact electrification and numerous capillary channels for thermal-moisture transfer. Through adjusting the concentration of Ag NW and the selection of PVA and PLGA, the antibacterial and biodegradable capability of e-skins can be tuned, respectively. Our e-skin can achieve real-time and self-powered monitoring of whole-body physiological signal and joint movement. This work provides a previously unexplored strategy for multifunctional e-skins with excellent practicability.

Tao Li, Mingchao Sun, Shaohua Wu

Nanomaterials • 2022

Electrospun nanofiber materials have been considered as advanced dressing candidates in the perspective of wound healing and skin regeneration, originated from their high porosity and permeability to air and moisture, effective barrier performance of external pathogens, and fantastic extracellular matrix (ECM) fibril mimicking property. Gelatin is one of the most important natural biomaterials for the design and construction of electrospun nanofiber-based dressings, due to its excellent biocompatibility and biodegradability, and great exudate-absorbing capacity. Various crosslinking approaches including physical, chemical, and biological methods have been introduced to improve the mechanical stability of electrospun gelatin-based nanofiber mats. Some innovative electrospinning strategies, including blend electrospinning, emulsion electrospinning, and coaxial electrospinning, have been explored to improve the mechanical, physicochemical, and biological properties of gelatin-based nanofiber mats. Moreover, numerous bioactive components and therapeutic agents have been utilized to impart the electrospun gelatin-based nanofiber dressing materials with multiple functions, such as antimicrobial, anti-inflammation, antioxidation, hemostatic, and vascularization, as well as other healing-promoting capacities. Noticeably, electrospun gelatin-based nanofiber mats integrated with specific functions have been fabricated to treat some hard-healing wound types containing burn and diabetic wounds. This work provides a detailed review of electrospun gelatin-based nanofiber dressing materials without or with therapeutic agents for wound healing and skin regeneration applications.

Elahe Fallah Talooki, M. Ghorbani, M. Rahimnejad et al.

Environmental Technology • 2023

ABSTRACT Photo-assisted microbial fuel cells (PMFCs) are novel bioelectrochemical systems that employ light to harvest bioelectricity and efficient contaminant reduction. In this study, the impact of different operational conditions on the electricity generation outputs in a photoelectrochemical double chamber configuration Microbial fuel cell using a highly useful photocathode are evaluated and their trends are compared with the photoreduction efficiency trends. As a photocathode, a binder-free photo electrode decorated with dispersed polyaniline nanofiber (PANI)−cadmium sulphide Quantum Dots (QDs) is prepared here to catalyse the chromium (VI) reduction reaction in a cathode chamber with an improvement in power generation performance. Bioelectricity generation is examined in various process conditions like photocathode materials, pH, initial concentration of catholyte, illumination intensity and time of illumination. Results show that, despite the harmful effect of the initial contaminant concentration on the reduction efficiency of the contaminant, this parameter exhibits a superior ability for improving the power generation efficiency in a Photo-MFC. Furthermore, the calculated power density under higher light irradiation intensity has experienced a significant increase, which is due to an increment in the number of photons produced and an increase in their chance of reaching the electrodes surface. On the other hand, additional results indicate that the power generation decreases with the rise of pH and has witnessed the same trend as the photoreduction efficiency. GRAPHICAL ABSTRACT

Sunshine Holmberg, M. Rodríguez-Delgado, Ross D. Milton et al.

ACS Catalysis • 2015

In this study, the bioelectrocatalytic reduction of molecular oxygen by two highly thermostable laccase isoforms from a native strain of Pycnoporus sanguineus CS43 were evaluated and compared to commercially available laccase from Trametes versicolor (TvL). The laccase isoforms (LAC1 and LAC2) and TvL laccase were immobilized by orientation onto anthracene-modified multiwalled carbon nanotubes (AC-MWCNT), which were subsequently immobilized onto carbon nanofiber mat electrodes fabricated using a carbon MEMS (C-MEMS) process. The performances of the isoforms were evaluated at differing pHs, temperatures, and with various inhibitors under hydrodynamic and hydrostatic conditions. Both LAC1 and LAC2 had onset potentials of over +650 mV vs Ag/AgCl at pH 4.0, which are among the highest reported to date for any laccase bioelectrode. High current densities were also obtained, producing 825 ± 88 μA/cm2 and 1220 ± 106 μA/cm2 with LAC1 and LAC2, respectively. The bioelectrodes also demonstrated remarkable operation...

Hamza Abdalla Yones

International Journal of Electrochemical Science • 2021

MgO decorated carbon nanofiber (MgO@CNFs) nanocomposite was prepared by electrospinning and carbonization method. Then the nanocomposite was casted on carbon ionic liquid electrode (CILE) with the following immobilization of hemoglobin (Hb) by Nafion polymer film. UV-Vis spectroscopic results showed that Hb maintained its original structure without changing after mixing with nanocomposite. The resultant MgO@CNFs modified electrode provided a favorable microenvironment for Hb to realize electrochemistry and the bioelectrochemical properties of Hb were studied in details. The results showed that MgO@CNFs nanocomposite on electrode improved Hb loading amount with its bioactivity maintained and electron transfer rate fasten, which was attributed to big specific interface area, excellent biocompatibility and high conductivity. Nafion/Hb/MgO@CNFs/CILE also displayed high electrocatalytic activity to the electroreduction of trichloroacetic acid. This study provided a novel way for the fabrication of the nanostructured biosurfaces for electrochemical biosensors.

Kyoung-im Kim, Dong-Ae Kim, K. Patel et al.

Scientific Reports • 2019

Although PMMA-based biomaterials are widely used in clinics, a major hurdle, namely, their poor antimicrobial (i.e., adhesion) properties, remains and can accelerate infections. In this study, carboxylated multiwalled carbon nanotubes (CNTs) were incorporated into poly(methyl methacrylate) (PMMA) to achieve drug-free antimicrobial adhesion properties. After characterizing the mechanical/surface properties, the anti-adhesive effects against 3 different oral microbial species (Staphylococcus aureus, Streptococcus mutans, and Candida albicans) were determined for roughened and highly polished surfaces using metabolic activity assays and staining for recognizing adherent cells. Carboxylated multiwalled CNTs were fabricated and incorporated into PMMA. Total fracture work was enhanced for composites containing 1 and 2% CNTs, while other mechanical properties were gradually compromised with the increase in the amount of CNTs incorporated. However, the surface roughness and water contact angle increased with increasing CNT incorporation. Significant anti-adhesive effects (35~95%) against 3 different oral microbial species without cytotoxicity to oral keratinocytes were observed for the 1% CNT group compared to the PMMA control group, which was confirmed by microorganism staining. The anti-adhesive mechanism was revealed as a disconnection of sequential microbe chains. The drug-free antimicrobial adhesion properties observed in the CNT-PMMA composite suggest the potential utility of CNT composites as future antimicrobial biomaterials for preventing microbial-induced complications in clinical settings (i.e., Candidiasis).

S. Vasquez, M. C. Angeli, Andrea Polo et al.

Scientific Reports • 2024

In vitro simulators of the human gastrointestinal (GI) tract are remarkable technological platforms for studying the impact of food on the gut microbiota, enabling continuous and real-time monitoring of key biomarkers. However, comprehensive real-time monitoring of gaseous biomarkers in these systems is required with a cost-effective approach, which has been challenging to perform experimentally to date. In this work, we demonstrate the integration and in-line use of carbon nanotube (CNT)-based chemiresitive gas sensors coated with a thin polydimethylsiloxane (PDMS) membrane for the continuous monitoring of gases within the Simulator of the Human Microbial Ecosystem (SHIME). The findings demonstrate the ability of the gas sensor to continuously monitor the different phases of gas production in this harsh, anaerobic, highly humid, and acidic environment for a long exposure time (16 h) without saturation. This establishes our sensor platform as an effective tool for real-time monitoring of gaseous biomarkers in in vitro systems like SHIME.

Huanan Wu, Min Lu, Lin Guo et al.

Water Science and Technology • 2014

<jats:p>Polyelectrolyte–single wall carbon nanotube (SCNT) composites are prepared by a solution-based method and used as metal-free cathode catalysts for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). In this study, two types of polyelectrolytes, polydiallyldimethylammonium chloride (PDDA) and poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (PEPU) are applied to decorate the SCNTs and the resulting catalysts exhibit remarkable catalytic ability toward ORR in MFC applications. The enhanced catalytic ability could be attributed to the positively charged quaternary ammonium sites of polyelectrolytes, which increase the oxygen affinity of SCNTs and reduce activation energy in the oxygen reduction process. It is also found that PEPU–SCNT composite-based MFCs show efficient performance with maximum power density of 270.1 mW m−2, comparable to MFCs with the benchmark Pt/C catalyst (375.3 mW m−2), while PDDA–SCNT composite-based MFCs produce 188.9 mW m−2. These results indicate that PEPU–SCNT and PDDA–SCNT catalysts are promising candidates as metal-free cathode catalysts for ORR in MFCs and could facilitate MFC scaling up and commercialization.</jats:p>

Sean L. Edwards, Ronen Fogel, Kudzai Mtambanengwe et al.

Journal of Porphyrins and Phthalocyanines • 2012

<jats:p> Pioneering work by Nyokong and others have highlighted the potential benefits for improved electron transfer processes and catalysis of hybrid configurations of metallophthalocyanines with carbon nanotubes. Here we examine the practical application of such hybrid configurations in an Enterobacter cloacae microbial fuel cell. Electrochemical investigations at glassy carbon electrodes (GCEs) showed that FePc and FePc :multiwalled carbon nanotube (MWCNT) hybrid surface modifications display significant oxygen reduction reaction electrocatalytic properties compared to either MWCNT-modified or bare GCE surfaces throughout acidic- to moderately-alkaline pHs. Significant stabilization of the current response at FePc :MWCNT surfaces are notable throughout the pH range, compared to GCE surfaces modified with FePc alone. Corresponding results were obtained for surface modifications of bare carbon paper (BCP) cathodes in a microbial fuel cell where power density increases were observed in the order: Pt &gt; FePc :MWCNT &gt; FePc &gt; MWCNT &gt; BCP. A synergistic combination of simple treatments such as increased ionic strength (300 mM NaCl ), temperature (35 °C), and agitation of the anode chamber in this MFC configuration increased the power density to 2.5 times greater than that achieved at platinised cathode configurations under non-optimised conditions, achieving peak power densities of 212 mW.m<jats:sup>-2</jats:sup>. The long-term stability of the MFC was assessed over 55 days. Surprisingly, the majority of signal loss over extended MFC operation was attributed, in this study, to fouling of the Nafion® PEM membrane rather than either leaching/fouling of the catalysts from the electrodes or nutrient depletion in the anode over the time periods examined. </jats:p>

Dang Huu Phuc, Ha Thanh Tung

International Journal of Photoenergy • 2019

<jats:p>Quantum dots are drawing great attention as a material for the next-generation solar cells because of the high absorption coefficient, tunable band gap, and multiple exciton generation effect. In search of the viable way to enhance the power conversion efficiency of quantum dot-sensitized solar cells, we have succeeded in preparing the quantum dot solar cells with high efficiency based on CdSe:X (Mn<jats:sup>2+</jats:sup> or Cu<jats:sup>2+</jats:sup>) nanocrystal by successive ionic layer absorption and reaction. The morphological observation and crystalline structure of photoanode were characterized by field-emission scanning electron microscopy, X-ray diffraction, and the EDX spectra. In addition, the electrochemical performance of photoelectrode was studied by the electrochemical impedance spectra. As a result, we have succeeded in designing QDSSCs with a high efficiency of 4.3%. Moreover, the optical properties, the direct optical energy gap, and both the conduction band and the valence band levels of the compositional CdSe:X were estimated by the theory of Tauc and discussed details. This theory is useful for us to understand the alignment energy structure of the compositions in electrodes, in particular, the conduction band and valence band levels of CdSe:X nanoparticles.</jats:p>

Seungjae Lee, Jieun Lee, Changjin Lee et al.

ECS Meeting Abstracts • 2020

<jats:p> Quantum dots (QD) have been researched intensively among several luminescent materials because they can simply adjust wavelength, high efficiency, high stability, and high color purity properties. In particular, eco-friendly InP based core-shell QDs without environmental regulations (i.e., restriction of hazardous substances in Europe) has been a great of attention.<jats:sup>1</jats:sup> However, it is difficult to synthesize InP-based core-shell QDs, which requires a high temperature, a long reaction time, and a high reactivity precursor since the InP-based core-shell QDs need a strong covalent bonds, degrading quantum yield(QY)<jats:sup>2</jats:sup>. For this reason, many defects in QDs are generated during a InP core growth. Among the blue(B)-, green(G)-, and red(R)-light emitting QDs, especially R-light emitting InP based core-shell QDs contain numerous crystalline defects since the core size should be increased to reduce the energy band gap. In our study, we enhanced highly QY of R-light emitting InP based core-shell QDs(R-QDs) by doping potassium ions via injecting potassium ion precursor such as potassium iodide during a InP core growth. We characterized the mechanism why potassium ion doping highly enhanced QY by observing the crystallinity of core-shell QD and electron paramagnetic resonance(EPR) analysis.</jats:p> <jats:p>In general, the R-QDs contain vacancy defect in the InP core-QDs which emit the red-light with ~625-nm in wavelength, degrading QY by lattice scattering, as shown in Fig. 1(a). These vacancy defects induced lattice-scattering and cause a decrease of QY. Here, the vacancy defects in the InP core-QDs would be passivated by doping potassium ions via using potassium iodide as a dopant, as shown in Fig. 1(b). In the InP core-QDs, the mole fraction of potassium ions to indium ions linearly increased with the potassium iodide concentration, measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), as shown in Fig. 1(c). Then, the InP core/ZnSe inter-shell/ZnSeS inter-shell/ZnS oueter-shell QDs (i.e.; InP core-shell QDs) were synthesized by using a precipitation method. The QY of the InP core-shell QDs peaked at a specific potassium iodide concentration; i.e., 91% at the potassium iodide concentration of 3%, as shown in Fig. 1(d). Otherwise, both full-width at half maximum (FWHM) and the wavelength emitting red-light gradually increased with the potassium iodide concentration.</jats:p> <jats:p>To understand the dependency of QY on the potassium iodide concentration, the crystallinity of InP core-shell QDs were investigated as a function of the potassium iodide concentration during growing the InP core-QDs, where in four different crystalline plane peaks were found; (unknown), (111), (220), and (311), as shown in Fig. 1(e). Particularly, the crystalline peak intensity of (unknown) rapidly increased with increasing QY, indicating the doping of potassium ions during growing the InP core-QDs passivated vacancy defects so that it suppressed an un-proper growth along unknown crystalline direction, as shown in Fig. 1(e). In addition, the exciton lifetime exponentially increased with QY, measured by time-resolved photoluminescence (TRPL), meaning that the passivation of vacancy defects with potassium ions enhanced the exciton lifetime of the InP core-shell QDs. It was found that there was a good correlation between QY and the crystalline peak intensity of (unknown) or the exciton lifetime, implying that the passivation of vacancy defects in the InP core-QDs by doping potassium iodide ions would enhance the QY of the InP core-shell QDs, as shown in Fig.1(f). Finally, the international commission on illumination (CIE) 1931 color spaces of a QD OLED display using R-, G-, and B-QD functional color filters, as shown in Fig.1(g), achieved 121.7% (NTSC) and 91.1% (Rec. 2020), as shown in Fig. 1(h) inset figure.</jats:p> <jats:p> <jats:bold>Reference</jats:bold> </jats:p> <jats:p>[1] Tamang, S.; Lincheneau, C.; Hermans, Y.; Jeong, S.; Reiss, P.; (2016). Chemistry of InP Nanocrystal Syntheses. Chem. Mater. 28, 2491−2506</jats:p> <jats:p>[2] Jang, E.; Kim, Y.; Won, Y.; Jang, H.; Choi, S.; (2020). Environmentally Friendly InP-Based Quantum Dots for Efficient Wide Color Gamut Displays. ACS Energy Lett. 5, 1316−1327</jats:p> <jats:p> <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2728fig1.jpg" xlink:type="simple"/> </jats:inline-formula> </jats:p> <jats:p>Figure 1</jats:p> <jats:p/>

Junyeong An, Hongrae Jeon, Jaeyoung Lee et al.

Environmental Science &amp; Technology • 2011

Organic contamination of water bodies in which benthic microbial fuel cells (benthic MFCs) are installed, and organic crossover from the anode to the cathode of membraneless MFCs, is a factor causing oxygen depletion and substrate loss in the cathode due to the growth of heterotrophic aerobic bacteria. This study examines the possible use of silver nanoparticles (AgNPs) as a cathodic catalyst for MFCs suffering from organic contamination and oxygen depletion. Four treated cathodes (AgNPs-coated, Pt/C-coated, Pt/C+AgNPs-coated, and plain graphite cathodes) were prepared and tested under high levels of organics loading. During operation (fed with 50 mM acetate), the AgNPs-coated system showed the highest DO concentration (0.8 mg/L) in the cathode area as well as the highest current (ranging from 0.04 to 0.12 mA). Based on these results, we concluded that (1) the growth of oxygen-consuming heterotrophic microbes could be inhibited by AgNPs, (2) the function of AgNPs as a bacterial growth inhibitor resulted in a greater increase of DO concentration in the cathode than the other tested cathode systems, (3) AgNPs could be applied as a cathode catalyst for oxygen reduction, and as a result (4) the MFC with the AgNPs-coated cathode led to the highest current generation among the tested MFCs.

Bocheng Cao, Zipeng Zhao, Lele Peng et al.

Science • 2021

Description Silver in the linings The bacterium Shewanella oneidensis is well known to use extracellular electron sinks, metal oxides and ions in nature or electrodes when cultured in a fuel cell, to power the catabolism of organic material. However, the power density of microbial fuel cells has been limited by various factors that are mostly related to connecting the microbes to the anode. Cao et al. found that a reduced graphene oxide–silver nanoparticle anode circumvents some of these issues, providing a substantial increase in current and power density (see the Perspective by Gaffney and Minteer). Electron microscopy revealed silver nanoparticles embedded or attached to the outer cell membrane, possibly facilitating electron transfer from internal electron carriers to the anode. —MAF A silver nanoparticle anode greatly boosts the performance of Shewanella biofilm–based microbial fuel cells. Microbial fuel cells (MFCs) can directly convert the chemical energy stored in organic matter to electricity and are of considerable interest for power generation and wastewater treatment. However, the current MFCs typically exhibit unsatisfactorily low power densities that are largely limited by the sluggish transmembrane and extracellular electron-transfer processes. Here, we report a rational strategy to boost the charge-extraction efficiency in Shewanella MFCs substantially by introducing transmembrane and outer-membrane silver nanoparticles. The resulting Shewanella-silver MFCs deliver a maximum current density of 3.85 milliamperes per square centimeter, power density of 0.66 milliwatts per square centimeter, and single-cell turnover frequency of 8.6 × 105 per second, which are all considerably higher than those of the best MFCs reported to date. Additionally, the hybrid MFCs feature an excellent fuel-utilization efficiency, with a coulombic efficiency of 81%.

Shenlong Zhao, Yuchen Li, H. Yin et al.

Science Advances • 2015

A microbial fuel cell constructed with 3D freestanding graphene aerogel/platinum nanoparticles shows unprecedented performance. Microbial fuel cells (MFCs) are able to directly convert about 50 to 90% of energy from oxidation of organic matters in waste to electricity and have great potential application in broad fields such as wastewater treatment. Unfortunately, the power density of the MFCs at present is significantly lower than the theoretical value because of technical limitations including low bacteria loading capacity and difficult electron transfer between the bacteria and the electrode. We reported a three-dimensional (3D) graphene aerogel (GA) decorated with platinum nanoparticles (Pt NPs) as an efficient freestanding anode for MFCs. The 3D GA/Pt–based anode has a continuous 3D macroporous structure that is favorable for microorganism immobilization and efficient electrolyte transport. Moreover, GA scaffold is homogenously decorated with Pt NPs to further enhance extracellular charge transfer between the bacteria and the anode. The MFCs constructed with 3D GA/Pt–based anode generate a remarkable maximum power density of 1460 mW/m2, 5.3 times higher than that based on carbon cloth (273 mW/m2). It deserves to be stressed that 1460 mW/m2 obtained from the GA/Pt anode shows the superior performance among all the reported MFCs inoculated with Shewanella oneidensis MR-1. Moreover, as a demonstration of the real application, the MFC equipped with the freestanding GA/Pt anode has been successfully applied in driving timer for the first time, which opens the avenue toward the real application of the MFCs.

Da Li, Youpeng Qu, Jia Liu et al.

ACS Applied Materials &amp; Interfaces • 2016

A biofilm growing on an air cathode is responsible for the decreased performance of microbial fuel cells (MFCs). For the undesired biofilm to be minimized, silver nanoparticles were synthesized on activated carbon as the cathodic catalyst (Ag/AC) in MFCs. Ag/AC enhanced maximum power density by 14.6% compared to that of a bare activated carbon cathode (AC) due to the additional silver catalysis. After operating MFCs over five months, protein content on the Ag/AC cathode was only 38.3% of that on the AC cathode, which resulted in a higher oxygen concentration diffusing through the Ag/AC cathode. In addition, a lower pH increment (0.2 units) was obtained near the Ag/AC catalyst surface after biofouling compared to 0.8 units of the AC cathode, indicating that less biofilm on the Ag/AC cathode had a minor resistance on hydroxide transported from the catalyst layer interfaces to the bulk solution. Therefore, less decrements of the Ag/AC activity and MFC performance were obtained. This result indicated that accelerated transport of oxygen and hydroxide, benefitting from the antibacterial property of the cathode, could efficiently maintain higher cathode stability during long-term operation.

Kasparas Kižys, Domas Pirštelis, I. Morkvėnaitė-Vilkončienė

Biosensors • 2024

Microbial fuel cells (MFCs) are a candidate for green energy sources due to microbes’ ability to generate charge in their metabolic processes. The main problem in MFCs is slow charge transfer between microorganisms and electrodes. Several methods to improve charge transfer have been used until now: modification of microorganisms by conductive polymers, use of lipophilic mediators, and conductive nanomaterials. We created an MFC with a graphite anode, covering it with 9,10-phenatrenequinone and polypyrrole-modified Saccharomyces cerevisiae with and without 10 nm sphere gold nanoparticles. The MFC was evaluated using cyclic voltammetry and power density measurements. The peak current from cyclic voltammetry measurements increased from 3.76 mA/cm2 to 5.01 mA/cm2 with bare and polypyrrole-modified yeast, respectively. The MFC with polypyrrole- and nanoparticle-modified yeast reached a maximum power density of 150 mW/m2 in PBS with 20 mM Fe(III) and 20 mM glucose, using a load of 10 kΩ. The same MFC with the same load in wastewater reached 179.2 mW/m2. These results suggest that this MFC configuration can be used to improve charge transfer.

Yanmei Sun, Jincheng Wei, Peng Liang et al.

AMB Express • 2012

<jats:title>Abstract</jats:title> <jats:p>Biocathode MFCs using microorganisms as catalysts have important advantages in lowering cost and improving sustainability. Electrode materials and microbial synergy determines biocathode MFCs performance. In this study, four materials, granular activated carbon (GAC), granular semicoke (GS), granular graphite (GG) and carbon felt cube (CFC) were used as packed cathodic materials. The microbial composition on each material and its correlation with the electricity generation performance of MFCs were investigated. Results showed that different biocathode materials had an important effect on the type of microbial species in biocathode MFCs. The microbes belonging to Bacteroidetes and Proteobacteria were the dominant phyla in the four materials packed biocathode MFCs. <jats:italic>Comamonas</jats:italic> of Betaproteobacteria might play significant roles in electron transfer process of GAC, GS and CFC packed biocathode MFCs, while in GG packed MFC <jats:italic>Acidovorax</jats:italic> may be correlated with power generation. The biocathode materials also had influence on the microbial diversity and evenness, but the differences in them were not positively related to the power production.</jats:p>

Nazish Parveen, Thi Hiep Han, Sajid Ali Ansari et al.

Journal of Nanoelectronics and Optoelectronics • 2021

<jats:p>The widespread use of renewable energy remains a challenging and complex multidisciplinary problem. Developing alternatives using new technology such as nanotechnology is necessary to increase renewable energy’s scalability. Microbial fuel cells (MFCs) combined with nanotechnology can improve bioelectricity generation during wastewater treatment. In this study, hollow carbon nanofibers (H-CNF) were decorated with manganese oxide (MnO<jats:sub>2</jats:sub>) via a simple chemical reduction method. MnO<jats:sub>2</jats:sub>-decorated H-CNF prepared with varying concentrations of manganese precursor (MnO<jats:sub>2</jats:sub>@H-CNF) were characterized via different spectroscopic and microscopic techniques. The cathode catalyst performance of the MnO<jats:sub>2</jats:sub>@H-CNF was investigated in an //-type constructed MFC system using <jats:italic>Shewanella Oneidensis</jats:italic> MR1. The MnO<jats:sub>2</jats:sub>@H-CNF-1 in the assembled MFC displayed excellent power density of 25.7 mW/m<jats:sup>2</jats:sup>, which is higher than pure H-CNF (8.66 mW/m<jats:sup>2</jats:sup>), carbon cloth (5.10 mW/m<jats:sup>2</jats:sup>), and MnO<jats:sub>2</jats:sub>@H-CNF-3 (16 mW/m<jats:sup>2</jats:sup>). The maximum power generated in the MFC coupled with MnO<jats:sub>2</jats:sub>@H-CNF as a cathode catalyst may have been due to the synergistic effect of the MnO<jats:sub>2</jats:sub>@H-CNF, which increased the electric conductivity and catalytic activity in the MFC’s cathode chamber. These results demonstrate that the developed MnO<jats:sub>2</jats:sub>@H-CNF cathode catalyst could improve the MFC’s performance and reduce the operational costs of practical applications.</jats:p>

Dohyun Kim, Rui Sun, Yossef A. Elabd

Fuel Cells • 2025

<jats:title>ABSTRACT</jats:title><jats:p>In this study, we developed a new technique, simultaneous foam electrospinning and electrospraying (FE/E), that produces nanofiber/nanoparticle electrodes at higher production rates compared to needle‐based electrospinning and electrospraying (E/E). Herein, the nanofiber amount was precisely controlled by applying various voltages on the foam electrospinning process at a fixed platinum (Pt) loading, which enables an exclusive investigation into the impact of ionomer nanofiber on fuel cell performance at ultra‐low Pt loadings for proton exchange membrane fuel cells. The results show that fuel cell performance is strongly dependent on ionomer nanofiber content. At 0.04 mg/cm<jats:sup>2</jats:sup> nanofiber amount, the electrodes exhibited the highest fuel cell power density of 1.09 W/cm<jats:sup>2</jats:sup> and Pt utilization of 11.5 kW/g<jats:sub>Pt</jats:sub>, which are 28% and 39% higher than those of the electrode produced via electrospraying alone, respectively. The improvement results from enhanced proton and gas transport stemming from the nanofiber network as verified by cyclic voltammetry, electrochemical impedance spectroscopy, and oxygen gain voltage analysis. The FE/E technique provides a pathway to produce ultra‐low Pt nanofiber/nanoparticle electrodes at high production rates and high fuel cell performance.</jats:p>

Hong Liu, Vinay Kumar, V. Yadav et al.

Bioengineered • 2021

ABSTRACT Biochar’s ability to mediate and facilitate microbial contamination degradation, as well as its carbon-sequestration potential, has sparked interest in recent years. The scope, possible advantages (economic and environmental), and future views are all evaluated in this review. We go over the many designed processes that are taking place and show why it is critical to look into biochar production for resource recovery and the role of bioengineered biochar in waste recycling. We concentrate on current breakthroughs in the fields of engineered biochar application techniques to systematically and sustainable technology. As a result, this paper describes the use of biomass for biochar production using various methods, as well as its use as an effective inclusion material to increase performance. The impact of biochar amendments on microbial colonisation, direct interspecies electron transfer, organic load minimization, and buffering maintenance is explored in detail. The majority of organic and inorganic (heavy metals) contaminants in the environment today are caused by human activities, such as mining and the use of chemical fertilizers and pesticides, which can be treated sustainably by using engineered biochar to promote the establishment of a sustainable engineered process by inducing the circular bioeconomy. GRAPHICAL ABSTRACT