Enhanced catalytic oxidation of hydrazine of CoO/Co3O4 heterojunction on N-doped carbon

The efficiency of direct hydrazine fuel cells (DHFC) depends largely on the electrocatalyst. Here, the composites of Co-based nanoparticles anchored on nitrogen-doped carbon substrates for hydrazine oxidation reaction (HzOR) were successfully synthesized by hydrothermal and pyrolytic methods. The optimal CoO/Co3O4@NC-600, which has the characteristic of heterojunction structure confirmed by XRD, showed excellent activity and durability for HzOR under alkaline conditions which also exceeds that of commercial Pt/C catalyst, which was ascribed to the fact that CoO/Co3O4 heterojunction is more favorable to the adsorption and dehydrogenation of N2H4 verified by density functional theory (DFT) calculation, and the mesoporous feature of CoO/Co3O4@NC-600 is conducive to the penetration of electrolyte. Furthermore, an electrolyzer of CoO/Co3O4@NC-600||Pt/C was assembled under alkaline medium, it requires a voltage of 0.35 V in the electrolyte of KOH (1.0 M) + N2H4 (0.5 M), which is much lower than that (1.75 V) in KOH (1.0 M) electrolyte, indicating that hydrazine-assisted hydrogen production is more energy-saving.