In Nin/Ga2O3 systems, the reaction sites of HER are predicted to be on Nin clusters.
The addition of NinOn cluster makes the decomposition process of water in Ga2O3 photocatalyst more favorable.
The strength of interfacial hydrogen bond is highly related to the stability of adsorption structure.
The overpotential needed for OER on NinOn/Ga2O3 is remarkably lower than that on clean Ga2O3 surface.
Theoretical findings provide reasonable explanations on experimental observations in NiOx/Ga2O3 photocatalyst.