Morphology and interfacial charge regulation strategies constructing 3D flower-like Co@CoP2 heterostructure electrocatalyst for efficient overall water splitting

Transition metal phosphide (TMP) is one of the most potential electrocatalysts for hydrogen evolution reaction (HER), whereas it is still immensely challenging to construct TMP-based catalyst that performs the excellent catalytic activity for both HER and oxygen evolution reaction (OER) through the proper regulation strategies. Herein, the morphology and interfacial charge regulation strategies were proposed to construct 3D flower-like Co@CoP2 heterostructure electrocatalyst grown in situ on copper foam (CF) for HER and OER. The influence of the phytic acid concentration on the product morphology and composition was systematic investigation. The flower-like Co@CoP 2 Mott-Scottky heterostructure grown on CF (Co@CoP 2 /CF(1:1)) prepared under the optimal conditions shows the eminent electrocatalytic activity of HER with an overpotential of 55 mV and OER with an overpotential of 210 mV at a current density of 10 mA cm −2 in alkaline solution. Remarkably, Co@CoP 2 /CF(1:1)//Co@CoP 2 /CF(1:1) electrolyzer displays a prominent overall water splitting performance with a voltage of 1.54 V at the current density of 10 mA cm −2 , and maintained excellent stability over a period of 100 h operating in 1 M KOH, which is superior to the almost all the reported non-noble-metal-based electrocatalysts. Various ex situ characterizations and density functional theory (DFT) calculations manifested that the superior electrocatalytic performance of Co@CoP 2 /CF (1:1) was attributed to high P content, more important, the unique flower-like morphology and the efficient regulation of interfacial charge drived by the Mott-Scottky effect. This work offers a universal regulation strategy for improve electrocatalytic activity, and opens up a new way for the exploitation of the efficient bifunctional electrocatalysts.