Bi selectively doped SrTiO3-x nanosheets enhance photocatalytic CO2 reduction under visible light.

[Display omitted] • SrTiO 3-x nanosheets were synthesized by simple hydrothermal method; • Sr atom on the SrTiO 3-x surface is the active site of CO 2 adsorption and activation; • COO– and COOH are important intermediates in photocatalytic CO 2 reduction; Converting CO 2 into chemical energy by using solar energy is an environmental strategy to achieve carbon neutrality. In this paper, two dimensionality (2D) SrTiO 3-x nanosheets with oxygen vacancies were synthesized successfully. Oxygen vacancies will generate defect levels in the band structure of SrTiO 3-x. So, SrTiO 3-x nanosheets have good photocatalytic CO 2 reduction performance under visible light. In order to further improve its photocatalytic efficiency, Bi was used to dope Sr site and Ti site in SrTiO 3-x nanosheets respectively. It is found that Sr site is the adsorption site of CO 2 molecules. When Bi replaced Sr, CO 2 adsorption on the surface of SrTiO 3-x nanosheets was weakened. When Bi replaced Ti, there has no effect on CO 2 adsorption. Due to the synergistic effect of Bi doping, oxygen vacancies, and Sr active site, the 1.0% Bi-doped Ti site in SrTiO 3-x (1.0% Bi-Ti-STO) had the best photocatalytic performance under visible light (λ ≥ 420 nm). CO and CH 4 yields were 5.58 umol/g/h and 0.36 umol/g/h. Photocatalytic CO 2 reduction path has always been the focus of exploration. The in-situ FTIR spectrum proved the step of photocatalytic CO 2 reduction and COO– and COOH are important intermediates in the photocatalytic CO 2 reaction. [ABSTRACT FROM AUTHOR]