Grain-boundary surface terminations incorporating oxygen vacancies for selectively boosting CO₂ photoreduction activity

Developing highly active and stable photocatalysts is a crucial endeavor to harvest valuable carbon-based fuels and feedstocks for photocatalytic CO₂ conversion. The excellent photocatalysts must satisfy the thermodynamic condition for the redox reaction and possess the accelerated reaction kinetics. Here, we report a strategy using grain-boundary surface terminations and oxygen vacancies to synergistically and selectively boost photocatalytic CO₂ reduction activity. Thereinto, grain boundaries as bulk defects create high-energy surfaces by stabilizing dislocations that are kinetically trapped for catalysis owing to the lattice strain of the photocatalyst. Oxygen vacancies are used to tailor the band structure and enhance the adsorption ability of reactants or intermediates. High-energy surface structures arisen from these bulk defects may be more resistant to the relaxation effect, resulting in excellent stability for photocatalytic CO₂ reduction. In light of the anticipated increase for photocatalytic CO₂ reduction activity, this work provides a strategy for broader exploitation of bulk defects in heterogeneous catalysis.