Solid-State Proton Donors in Hydroxyl-Rich NiGeO(OH) for Solar-Driven Hydrogen Evolution.

The hydrogen evolution reaction (HER) through water splitting is one of the most promising solutions to global energy and environmental challenges. In this study, using hydroxyl-rich NiGeO(OH) as a photocatalyst, a novel, kinetically self-activated solar-driven gas-solid system for H production was demonstrated, where solid-state lattice hydroxyls (Ni-OH) serve as proton donors due to their low reaction barrier. The sustainable regeneration of Ni-OH is achieved through gaseous HO molecule dissociation at the resultant oxygen vacancies (O), which plays a critical role in enhancing proton activity. Under 5 h of testing, the system achieved a cocatalyst-free H yield of 311.8 μmol g at the gas-solid interface, approximately 35 times higher than that of the triphasic system, and even 3.4 and 2.1 times higher than HO splitting systems using triethanolamine or methanol as sacrificial agents, respectively. This work provides valuable insights into the design of advanced photocatalysts and the development of sustainable H production systems.