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

Abstract

Developing highly active and stable photocatalysts is a crucial endeavor to harvest valuable carbon-based fuels and feedstocks for photocatalytic CO 2 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 CO 2 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 CO 2 reduction. In light of the anticipated increase for photocatalytic CO 2 reduction activity, this work provides a strategy for broader exploitation of bulk defects in heterogeneous catalysis. • The lattice strain can create high-energy surfaces for the catalytic reaction, which are kinetically trapped. • The oxygen vacancy can induce the defect level generation and lower Sn coordination numbers. • The experimental results explicitly link grain boundaries and oxygen vacancies to photocatalytic CO 2 reduction activity.