Design of atomically dispersed N-Bi(3+x)+--OV sites in ultrathin Bi2O2CO3 nanosheets for efficient and durable visible-light-driven CO2 reduction

The introduction of oxygen vacancies (OVs) into photocatalysts has proven to be a successful tactic to boost CO2 reduction. However, the challenge lies in acquiring OV sites that are stable in the long term, highly dispersed, and tunable in concentration. Herein, an innovative configuration, referred to as N-Bi(3+x)+--OV, was developed for the model semiconductor Bi2O2CO3 via an in situ anion doping approach. The structure enables the synthetic photocatalyst to exhibit superb CO2 photoreduction performance, with approximately 100% CO selectivity and remarkable long-term stability. Experimental studies and density functional theory (DFT) calculations show that replacing O2- with N3- uniformly in the [Bi2O2]2+ structural unit increases the chemical valence of Bi, elongates nearby Bi─O bonds, releases lattice O, improves CO2 absorption, and decreases the energy barrier for the formation of the critical intermediate *COOH. This study offers new insights and potential opportunities for the development of reliable defect-type semiconductors and their catalytic applications.