Fabrication of Hollow CoP/TiO_x Heterostructures for Enhanced Oxygen Evolution Reaction

Transition-metal phosphides have flourished as promising candidates for oxygen evolution reaction (OER) electrocatalysts. Herein, it is demonstrated that the electrocatalytic OER performance of CoP can be greatly improved by constructing a hybrid CoP/TiO_x heterostructure. The CoP/TiO_x heterostructure is fabricated using metal–organic framework nanocrystals as templates, which leads to unique hollow structures and uniformly distributed CoP nanoparticles on TiO_x. The strong interactions between CoP and TiO_x in the CoP/TiO_x heterostructure and the conductive nature of TiO_x with Ti³⁺ sites endow the CoP–TiO_x hybrid material with high OER activity comparable to the state-of-the-art IrO₂ or RuO₂ OER electrocatalysts. In combination with theoretical calculations, this work reveals that the formation of CoP/TiO_x heterostructure can generate a pathway for facile electron transport and optimize the water adsorption energy, thus promoting the OER electrocatalysis.