Construction of p–n Heterostructures with Built-In Electric Fields for Efficient Oxygen Evolution Reaction

Designing electrocatalysts that are both highly efficient and remarkably stable for the oxygen evolution reaction (OER) holds immense significance in enhancing the performance efficiency of water electrolysis within renewable energy systems. In this study, a MoSe₂@NiFe₂O₄ p-n heterostructure was constructed to effectively regulate the interfacial built-in electric field (BIEF), thereby tuning the electronic distribution and transfer behavior and optimizing the adsorption/desorption reaction kinetics. Structural and electronic characterizations confirmed a pronounced work function difference (Δ = 1.9 eV) between MoSe₂ and NiFe₂O₄, which drives spontaneous electron migration from MoSe₂ to NiFe₂O₄. This leads to the generation of a strong BIEF at the interface, which, in turn, promotes efficient separation and transfer of charge. Benefiting from this, the MoSe₂@NiFe₂O₄ electrode exhibits outstanding OER performance in 1.0 M KOH, requiring only 212 mV to achieve a current density of 10 mA cm^-2 and 290 mV to deliver 1000 mA cm^-2, while sustaining a minimal overpotential and demonstrating exceptional stability, even when subjected to high current densities, thereby outperforming the majority of previously reported OER catalysts. This work demonstrates that exploiting work function differences to construct and regulate interfacial BIEF offers a new strategy and theoretical foundation for designing highly efficient OER electrocatalysts via interfacial engineering.