Interfacial engineering of the nickel/zinc oxides p-n heterojunction for promoting photo-assisted oxygen evolution reaction

To enhance oxygen evolution reaction (OER) kinetics, energy coupling strategies have been employed in electrocatalysis. Particularly, photo-assisted electrocatalysis has gained considerable attention due to its potential to reduce overpotential and fully utilize light energy. This study reports the synthesis of NiO/ZnO@NF self-supported heterojunctions on nickel foam (NF) via a single-step hydrothermal method as photo-assisted electrocatalysts to improve the catalytic performance of OER. The strong electronic interaction between Nickel oxide (NiO) and Zinc oxide (ZnO), coupled with the formation of p-n junction formation, improved the electronic structure of the material, resulting in superior OER performance. The results indicated that under illumination, NiO/ZnO@NF achieved a current density of 10 mA cm −2 with an overpotential of merely 268 mV, 27 mV lower than the overpotential under non-illuminated conditions. Furthermore, at a high current density of 50 mA cm −2 , it maintained a low overpotential of 330 mV, outperforming most RuO 2 catalysts. Additionally, NiO/ZnO@NF displayed remarkable stability under alkaline conditions. The heterojunction formation in NiO/ZnO@NF modifies the material’s band structure, reducing the band gap, implying lower energy required for electron transitions and promoting electron transfer rates. Furthermore, under illumination, the heterojunction structure effectively suppressed the recombination rate of photogenerated charge carriers. The photogenerated holes generated in the material after light excitation were transformed into more active species either by direct participation in the reaction or by accumulating on NiO, further enhancing the OER catalytic efficiency. This work provides a new strategy for designing efficient OER electrocatalysts using multi-energy synergies.