Vertically grown p–n heterojunction FeCoNi LDH/CuO arrays with modulated interfacial charges to facilitate the electrocatalytic oxygen evolution reaction

The built-in electric field at the heterogeneous interface makes FeCoNi LDH in p–n heterojunction FeCoNi LDH/CuO more positively charged, which is more favorable for the adsorption of OH − , leading to the promoted OER activity in the alkaline media.