Synthesis of uniformly dispersed NiCoFe trimetallic phosphide for efficient overall water splitting

Abstract

NiCoFe trimetallic phosphides are synthesized using NiCoFe layered double hydroxides (NiCoFe-LDH) as precursors to investigate the impact of a third transition metal dopant on water-splitting properties. The ordered arrangement of transition metal ions within the LDH structure facilitates the phosphorization process, resulting in uniformly dispersed Ni_xCo₂Fe–P composites. The heterojunctions between different adjacent phosphide species facilitate electron transfer, modulate the electronic structure of active sites, and improve electrocatalytic properties. Compared to bimetallic phosphide. The Ni_0.3Co₂Fe–P composite exhibits the highest catalytic performance in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH. At the current density of 10 mA cm⁻², the overpotential for HER and OER is only 91 mV and 290 mV, respectively. As a bifunctional electrocatalyst in an alkaline media, it requires a cell voltage of only 1.61 V to initiate the reaction, with stable electrolysis performance at 10 mA cm⁻² for at least 24 h without any deviation.