Heterointerface Engineering of Ni2P–Co2P Nanoframes for Efficient Water Splitting

Abstract

Designing highly active, stable, bifunctional, noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a major challenge in water splitting. We report here a novel, frame-like nanostructured catalyst (Ni,Co)₂P nanoframe (NF), which consists of heterostructured Ni₂P–Co₂P nanoparticles embedded in the N-doped carbon matrix. Its synthesis involves precipitation, chemical etching, and a final phosphidation step to give an optimized electronic structure that contains multiple catalytic active sites and facilitates mass transfer. The catalyst is a bifunctional catalyst for both HER and OER and is superior to the individual components Ni₂P and Co₂P samples and (Ni,Co)₂P solid nanocubes. When the (Ni,Co)₂P NF catalyst was employed as both the cathode and anode for overall water splitting, a remarkably low cell voltage of 1.54 V was required to achieve a current density of 10 mA cm^–2. Density functional theory calculations verify the strong electronic interaction between Ni₂P and Co₂P at the heterointerfaces, resulting in an optimized hydrogen adsorption strength for enhanced HER electrocatalysis. Moreover, the synthetic strategy has been generalized for the synthesis of Ni–Co dichalcogenide NFs, thereby holding a great promise for a variety of potential applications.

Heterointerface Engineering of Ni₂P–Co₂P Nanoframes for Efficient Water Splitting

DOI: 10.1021/acs.chemmater.1c02609