Alloy/Interface-Induced activation of Metal-Phosphorus bonds in Ni5Cu3/CoP for efficient water splitting

Abstract

Designing and fabricating heterostructure electrocatalysts composed of alloys and transition metal compounds might be a promising strategy for high-efficiency electrocatalysis. Herein, by anchoring a layer of Ni₅Cu₃ alloy on CoP nanorods with the help of an electrodeposition strategy, an efficient alloy-compound heterointerface catalyst for water splitting, Ni₅Cu₃/CoP, was designed and fabricated successfully. As shown from the experiments, the alloying effect of the Ni₅Cu₃/CoP catalyst induced a super-strong interfacial coupling due to the significant electron outflow from the Ni₅Cu₃ alloy, and it was the synergy of this alloying effect and super-strong interfacial coupling that resulted in the significant activation of cobalt-phosphorus bonds on the catalyst surface to generate rich active sites, which remarkably activated the intrinsic activity of Ni₅Cu₃/CoP. Therefore, in alkaline condition, Ni₅Cu₃/CoP exhibited low hydrogen evolution reaction (HER) overpotential of 66 mV and oxygen evolution reaction (OER) overpotential of 190 mV at 10 mA·cm⁻², respectively, as well as only needed a small cell voltage of 1.51 V to achieve 10 mA·cm⁻² for overall water splitting. Density functional theory (DFT) results revealed that alloy-induced strong interfacial coupling considerably optimized the adsorption of OER and HER intermediates, improving the catalytic activity. These findings provided a valuable insight for the subsequent development of heterogeneous catalysts containing alloy components.