Manipulating dehydrogenation kinetics through dual-doping Co 3 N electrode enables highly efficient hydrazine oxidation assisting self-powered H 2 production

Replacing sluggish oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) to produce hydrogen has been considered as a more energy-efficient strategy than water splitting. However, the relatively high cell voltage in two-electrode system and the required external electric power hinder its scalable applications, especially in mobile devices. Herein, we report a bifunctional P, W co-doped Co3N nanowire array electrode with remarkable catalytic activity towards both HzOR (−55 mV at 10 mA cm−2) and hydrogen evolution reaction (HER, −41 mV at 10 mA cm−2). Inspiringly, a record low cell voltage of 28 mV is required to achieve 10 mA cm−2 in two-electrode system. DFT calculations decipher that the doping optimized H* adsorption/desorption and dehydrogenation kinetics could be the underlying mechanism. Importantly, a self-powered H2 production system by integrating a direct hydrazine fuel cell with a hydrazine splitting electrolyzer can achieve a decent rate of 1.25 mmol h−1 at room temperature. While facile hydrazine oxidation could replace the sluggish H2O oxidation reaction in renewable H2 production, few bifunctional catalysts exist. Here, authors explore a dual-doping strategy for Co3N nanowires that bestows bifunctionality toward both hydrazine oxidation and H2 evolution catalysis.