Self-healing redox chemistry in Cu-TiO2 photocatalysts for enhanced hydrogen production.

Hydrogen production from sunlight and abundant feedstock is central to a sustainable energy future, yet most efficient photocatalysts rely on costly noble metals. Here we report a scalable one-pot synthesis of CuOx-TiO2 photocatalysts that achieve a methanol-assisted hydrogen evolution rate of 30.6 mmol g-1 h-1, among the highest reported for Cu-based systems. The optimized 12% CuOx-TiO2 maintains >90% activity retention over 50 h and performs reproducibly at the gram scale, underscoring its industrial potential. Spectroscopic and computational analyses uncover a dynamic CuO ⇆ Cu2O ⇆ Cu0 cycle and a previously unrecognized corrosion-healing redox loop, in which transient Cu(OH)2 is continuously reduced back to Cu2O by methanol-derived intermediates. This self-healing mechanism stabilizes the active Cu2O phase, suppresses deactivation, and sustains long-term performance. Density functional theory reveals near-optimal hydrogen adsorption free energy (ΔGH* = -0.06 eV) on Cu-TiO2(101), comparable to Pt(111), confirming copper's potential as a low-cost alternative to noble metals. These findings establish redox self-healing catalysis as a powerful design principle for durable, scalable, and earth-abundant photocatalysts for solar hydrogen production.