Nanoflower-Like CoP–CoWO₄ Heterostructures for Enhanced Oxygen Evolution Reaction

Optimizing the electronic structure is essential for designing high-performance oxygen evolution reaction (OER) catalysts. Although monometallic tungstates, such as CoWO4, exhibit OER activity, their performance is often limited. This study introduces a CoP–CoWO4 heterostructure featuring a spontaneous built-in electric field (BIEF) as a promising OER cathode catalyst. The BIEF, generated by the work function difference between CoP and CoWO4, promotes the electron transfer from CoWO4 to CoP, leading to an asymmetric charge distribution at the interface. This unique electronic structure optimizes the adsorption and desorption kinetics of oxygen intermediates, significantly enhancing OER performance. Functioning as an OER electrocatalyst in alkaline environments, CoP–CoWO4 demonstrates a low overpotential of 241 mV to reach 10 mA cm–2, exhibiting superior performance compared to its individual components (CoWO4 and CoP) and many reported cobalt-based catalysts. The rational design of high-performance electrocatalysts for energy conversion applications can be effectively guided by an interfacial engineering approach, as demonstrated by the modulation of electronic structures in this study, which offers valuable insights.