Promoting Effect of Tin on Binder‐Free CoSnₓ‐B/Ni‐foam Catalysts for Fuel Conversion Efficiency in Direct Borohydride Fuel Cell

Abstract

Abstract The anodic activity of anodic catalyst for borohydride oxidation reaction (BOR) and inhibiting the borohydride hydrolysis reaction (BHR) are crucial to development for direct borohydride fuel cells (DBFC). In this paper, binder free CoSn x ‐B/Ni‐foam ( x = 0, 0.33, 0.5, 1) anode catalysts for BOR were prepared by chemical reduction method. It is found that the tin (Sn) is favor for improving the catalytic activity of cobalt (Co) for BOR, meanwhile, the catalytic activity is in relation to Co/Sn atom ratios. A maximum power density of 158 mW cm −2 of DBFC anodic catalytic is achieved at 293 K using CoSn 0.33 ‐B/Ni‐foam which is 1.58 times that of Co‐B/Ni‐foam (100 mW cm −2 ). The constant discharge test of DBFCs showed that the specific capacity or fuel conversion efficiency decrease with the catalytic activity increasing. However, for the same electrocatalyst, the fuel conversion efficiency increased with the discharge current grown, indicating that there is a BHR which was independent of electrocatalyst in the discharge process. The results showed that CoSn x ‐B/Ni‐foam had superior activity for BOR, suggesting their potential application as anodes in DBFC.

Key findings

• ▸Tin improves catalytic activity of cobalt for borohydride oxidation reaction.
• ▸Catalytic activity is related to Co/Sn atom ratios.
• ▸Fuel conversion efficiency decreases with increasing catalytic activity.

Keywords

Identifiers

DOI

10.1002/fuce.201800180

Journal

Fuel Cells

Year

2019