CoS 2 Decorated on Nitrogen‐Rich Mesoporous Carbon as a Bifunctional Electrocatalyst for Effective Hydrazine‐Mediated Overall Water Splitting

ABSTRACT Hydrazine‐assisted electrochemical water splitting through hydrazine oxidation reaction (HzOR) at the anode to generate clean and green hydrogen is recognized as an energy‐efficient strategy and a feasible alternative to replace the slow oxygen evolution reaction (OER). Herein, a bifunctional catalyst CoS 2 /NOMC has been synthesized hydrothermally, where CoS 2 is embedded on a nitrogen‐rich, stable, and activated mesoporous carbon matrix (NOMC). The NOMC‐supported CoS 2 catalyst with high electrochemically active surface area (ECSA) exhibits a very good response toward the electrocatalytic oxidation of hydrazine in an alkaline medium. Compared to CoS 2 and NOMC, CoS 2 /NOMC shows superior activity for hydrazine oxidation and hydrogen evolution reaction with an onset potential of 0.538 V (SCE) and ‐0.398 V (RHE), respectively, for HzOR and HER. This is well reflected in its high electrochemical active surface area, low charge transfer resistance, and low Tafel slope (136 mV dec −1 for hydrazine oxidation and 82 mV dec −1 for HER). The composite catalyst also demonstrated good stability in an alkaline medium. The mesoporous carbon framework (NOMC) with considerably high BET surface area, interconnected ion diffusion channels, and large pore volume accelerates the electron transport through the porous surface, which makes CoS 2 /NOMC efficient electrocatalyst for the oxidation of hydrazine in alkaline medium.