Quenching to optimize the crystalline/amorphous ratio of CoPS nanorods for hydrazine-assisted total water decomposition at ampere-level current density

ABSTRACT Directional construction of crystalline/amorphous (c/a)-phosphosulfide heterostructures with exceptional intrinsic activity through a facile strategy is challenging. In this study, we synthesized q-CoPS nanorods with a unique c/a-CoPS core-shell heterostructure through the ‘gas-phase phosphorus vulcanization-quenching' treatment. This work also innovatively masters the regulation of the initial quenching temperature to alter the c/a ratio of the CoPS nanorods . Surprisingly, with increasing initial quenching temperature, the area of the amorphous CoPS shell gradually increases. Density functional theory calculations reveal that the Co sites at the c/a-heterointerface, as the difunctional c/a-interface active site, effectively optimize the kinetics of the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). As anticipated, q-CoPS/CF requires an overpotential of only 90 mV at a current density of 1000 mA cm –2 for the alkaline HER, which is much lower than that required using the state-of-the-art Pt/C catalyst. Additionally, q-CoPS/CF achieves a current density of 1000 mA cm –2 at only 0.06 V in the HzOR. Overall, this work proposes an efficient strategy for developing a bifunctional electrocatalyst with a unique c/a-heterostructure to address future energy needs.