Selective CO2 photoreduction to C2 hydrocarbon via synergy between metastable ordered oxygen vacancies and hydrogen spillover over TiO2 nanobelts

The development of photocatalysts with desirable compositions and structures to improve the selectivity of CO2 conversion to hydrocarbon remains a challenging goal. In this study, we present a strategy of defected TiO2 nanobelts with metastable ordered oxygen vacancies by a simple Pd-catalyzed oxygen reduction method under anoxic condition. Ordered oxygen vacancies not only provide the driving force and channel for the directional movement of photoinduced electrons by modulating built-in electric field, but also promote CO2 adsorption and activation. Pd nanoparticles (Pd NPs) boosted dissociation of H2O to increase H* coverage and promoted the protonation of the intermediates via hydrogen spillover. The synergistic effect of ordered oxygen vacancies and hydrogen spillover contributed to the enhanced photocatalytic reduction of CO2 toward C2 products. The maximum selectivity of C2 products can reach 51.45% with an evolution rate of 25.987 μmol·g−1·h−1. This strategy provides a convenient method for designing a selective CO2 conversion photocatalyst.