Optimizing TiO2 photocatalysts with Co and Ni loading for improved photoelectrocatalytic hydrogen production

This study investigates the synergistic effects of cobalt (Co) and nickel (Ni) co-loading on TiO 2 photocatalysts for enhanced photocatalytic hydrogen production. The Co-Ni/TiO 2 photocatalysts were synthesized via the sol-gel method and characterized using XRD, FESEM-EDX, BET, DRS, PL, and XPS analyses to elucidate their structural, optical, and electronic properties. FESEM and EDX results revealed that Co and Ni oxides were homogeneously dispersed across the TiO 2 surface without forming dense agglomerates, while XPS confirmed the coexistence of Co 2 + /Co 3+ and Ni 2+ /Ni 3+ species, indicating dynamic surface redox equilibria. The co-loading of Co and Ni facilitated spatial charge separation, where Co sites acted as hole traps promoting the oxygen evolution reaction (OER), and Ni sites served as electron sinks, favoring the hydrogen evolution reaction (HER). This dual redox functionality suppressed charge recombination and enhanced photocatalytic efficiency. The optimal Co-Ni/TiO 2 sample achieved a hydrogen evolution rate of 448 μmol h −1 g −1 , which was significantly higher than that of single-metal or undoped TiO 2 . Stability tests demonstrated consistent performance over three consecutive cycles, confirming excellent durability and reusability. Overall, the synergistic interaction between Co and Ni on TiO 2 presents an effective strategy for improving solar-driven hydrogen generation.