A major challenge in advancing direct hydrazine fuel cells (DHFCs) is to fabricate effective and inexpensive electrocatalysts for hydrazine oxidation reaction (HzOR). Toward this goal, a hierarchical Co@Cu NRAs/CF electrode was fabricated using a two-step strategy. Cu nanorod arrays (Cu NRAs) were first grown in situ on Cu foam (CF) through anodic oxidation and chemical reduction, followed by electrodeposition of Co nanosheets. This electrode outperformed both the corresponding single-component electrodes (Co/CF and Cu NRAs/CF) and Pt/C catalyst in terms of electrocatalytic activity for HzOR. The Co@Cu NRAs/CF achieved 10 mA cm −2 at -0.046 V (vs. RHE), which was more negative than that of Pt/C (0.044 V). It displayed a current density of 281.4 mA cm −2 at 0.423 V (vs. RHE), representing a 143.5 mA cm −2 enhancement over Pt/C. Electrochemical kinetic analysis confirmed its enhanced reaction dynamics, reflected by the smallest Tafel slope, lowest activation energy ( E a ) and minimal charge transfer resistance ( R ct ) of all samples fabricated. The HzOR on Co@Cu NRAs/CF exhibited a four-electron transfer behavior with an almost 100% Faradaic efficiency. Its remarkable electrocatalytic efficiency stems from the hierarchical heterostructure of Co nanosheet-decorated Cu nanorods. • A heterostructured hierarchical Co nanosheet-decorated Cu nanorod is prepared. • Co@Cu NRAs/CF electrode shows better electrocatalytic activity than Pt/C catalyst. • Hydrazine oxidation reaction on Co@Cu NRAs/CF follows a four-electron pathway.
Liu et al. (Fri,) studied this question.