Morph-active: Compared with Pd−Ni@Ni plate and foam, nanowire arrays afford larger catalytic steady-state current density due to their morphology. Not only direct carbohydrazide electrooxidation, but also chemical decomposition of carbohydrazide into hydrazine/hydrogen/ammonia and then electrooxidation of hydrazine/hydrogen occur on the electrocatalyst. Ammonia cannot be further electrooxidized.
Considering the excessively high onset potential on pure Ni catalyst and the generation of gaseous products in carbohydrazide (CHZ) electrooxidation, a self-supporting and shell-core Pd−Ni@Ni nanowire arrays (NAs) catalytic electrode is prepared by the first templating electrodeposition of Ni and the subsequent galvanic replacement of Pd. The introduction of Pd with minute mass loadings of 2.7–5.3 μg cm−2 enables a negative shift of onset potential of CHZ electrooxidation by 320 mV regardless of Ni supports. Pd in Ni@Pd−Ni NAs electrode can facilitate the chemical dissociation of CHZ into N2H4 and/or H2 and then provoke the occurrence of side reactions, i. e., N2H4 and/or H2 electrooxidation. The direct CHZ fuel cell made of Ni@Pd−Ni NAs anode delivers an open circuit voltage of 1.05 V and a peak power density of 22.90 mV cm−2 at the operating temperature of 303 K.Zum Volltext