Preparation and overall water-splitting performance study of amorphous nickel-copper-phosphide

Abstract

Hydrogen energy is one of the most important vehicles for energy development in China. One of the effective hydrogen production pathways is overall water-splitting, which is considered as one of the most promising technologies for large-scale hydrogen production. However, its stability, activity, and selectivity still need to be improved. Therefore, in this article, amorphous nickel-copper phosphide was prepared by solvothermal method. Increasing the concentration of ethylene glycol in the solvent makes the solution viscosity increase, which inhibits the nucleation process of the crystal and causes structural distortion, leading to complete amorphization of the nickel-copper phosphide. After the analysis of physical phase and electrocatalytic properties, it can be concluded that the performance of the catalyst is optimal when completely amorphous. When the current density is 10 mA·cm−2, the overpotential of HER and OER are 140.5 and 232.65 mV respectively, and the overall water-splitting overpotential is 1.6404 V. Theoretical calculations indicate that the amorphous phase can optimize the electronic structure, thereby endowing the catalyst with excellent overall water-splitting catalytic activity and stability. This article demonstrates that the formation of an amorphous phase increases the number of active sites on the catalyst, enhancing its catalytic activity, and provides an explanation for the mechanism behind the catalytic performance. This research provides a theoretical foundation for the development of hydrogen production through electrochemical water splitting and expands the design strategies for catalysts.