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

Abstract

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)+--O_V, 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 O^2- with N^3- 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.