Wavelength-responsive in situ redox chemistry enables stable CO2 photocatalysis

Photocatalysis involves photogenerated charge carriers transferring to reactants via active sites. While carrier-reactant interactions are widely studied, carrier-site interactions remain overlooked. Here, we report a wavelength-gated in situ site regeneration strategy to improve catalyst stability. In photocatalytic CO2 reduction, the Au/Ce0.95Cu0.05O2-x solid-solution catalyst exhibited a high stability exceeding 48 h and a C2H6 production rate of 63.8 μmol g–1 h–1. Notably, the catalyst initially deactivates rapidly under 375 nm light but can be reactivated under 535 nm light. In situ spectroscopy and theoretical simulation attributed this to an in situ redox process involving the active sites and reactants. Under 375 nm light, the Cu+-O3-Ce site binds with dissociated O atoms from CO2, transforming to an inactive Cu2+-O4-Ce structure, which is subsequently reactivated by localized surface plasmon resonance hot electrons generated under 535 nm light. This work presents a universal strategy for designing catalysts with long-term stability. The authors report a wavelength-gated regeneration strategy, where specific wavelength photogenerated carriers drive the reversible cycling of active sites, enabling highly stable photocatalytic CO2 reduction to C2H6.