Ubiquitous Borane Fuel Electrooxidation on Pd/C and Pt/C Electrocatalysts: Toward Promising Direct Hydrazine–Borane Fuel Cells

Abstract

Carbon-supported platinum and palladium nanoparticles were studied toward the oxidation of several boranes (namely ammonia–borane (AB), dimethylamine–borane (DMAB), hydrazine–borane (HB), and hydrazine–bis-borane (HBB)); only palladium is capable to oxidize directly and efficiently these fuels, as platinum first decomposes the boranes and then valorizes the evolved H2 and adsorbed Had. Changing the nature of the borane fuel enables modulation of the borane oxidation performances at palladium electrodes; the best compromise is reached with HB (HBB suffers safety issues, and AB and DMAB are poisoned by the “counter-fragment” and/or its electroinactivity for any electrooxidation reaction). As a result, with a Pd/C electrode, HB oxidation is possible at low potential (close to the theoretical value), which holds promise for direct alkaline fuel cell applications. The temperature, HB concentration, and palladium nanoparticle loading on the electrode have remarkable effects, which shows that the “direct” electr...