Bimetal phosphide as high efficiency and stable bifunctional electrocatalysts for hydrogen and oxygen evolution reaction in alkaline solution

Abstract

The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts for large-scale water electrolysis is very important for the sustainable development of energy. In this paper, the nickel cobalt phosphide (CoNiP) microstructure was prepared by the “in situ growth-ion exchange-phosphating” method. Due to the flake structure and the synergistic effect of the bimetal, the synthesized CoNiP microstructure exhibited high electrocatalytic activity and stability for hydrogen and oxygen evolution in alkaline electrolyte. The optimized CoNiP showed low overpotential of 116 mV at 10 mA cm⁻² for hydrogen evolution reaction and 400 mV at 50 mA cm⁻² for oxygen evolution reaction in KOH solution. In addition, it exhibited long-term stability at a high constant current density of 100 mA cm⁻² for 48 hours at room temperature and for 65 hours at 80 °C without significant degradation. Theoretical results showed that the introduction of Co and P atoms could reduce the reaction barrier and improve the electron transfer ability. This work provides a simple and economical way for the synthesis of electrocatalytic bimetal phosphide catalysts.