Abstract 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 Co 3 N 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 H 2 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.