Facile Electrochemical Synthesis of Bifunctional Needle-like Co-P Nanoarray for Efficient Overall Water Splitting

The development of low-cost and high-performance bifunctional electrocatalysts for overall water splitting is still challenging. Herein, we employed a facile electrodeposition method to prepare bifunctional cobalt phosphide for overall water splitting. The needle-like cobalt phosphide (Co-P-1) nanoarray is uniformly distributed on nickel foam. Co-P-1 exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER, 85 mV at 10 mA/cm², 60 mV/dec) and oxygen evolution reaction (OER, 294 mV at 50 mA/cm², 60 mV/dec). The cell-voltage of 1.60 V is found to achieve the current density of 10 mA/cm² for overall water splitting in the two-electrode system, comparable to that of previously reported Pt/C/NF||RuO₂/NF. The excellent electrocatalytic performance can be attributed to the needle-like structure with more active sites, accelerated charge transfer and evolved bubbles' release. This work can provide new approach to the development of a bifunctional electrocatalyst for overall water splitting.