Weina Shi, Leilei Zhang*, Ran Zhang, Baocheng Yang, Jiao Guo*, Xiaowei Guo, Haoran Ma*, Ji-Chao Wang*

Cite this article: Chin. J. Struct. Chem., 2026, 45(7), 100913. DOI: 10.1016/j.cjsc.2026.100913

Publication date: July 1, 2026

Keywords: S-scheme photocatalyst; CO₂ reduction; Surface defect; Product selectivity; CuBi₂O₄/BiOI

ABSTRACT

S-scheme heterojunction has demonstrated high superiority in the separation and transfer of charge carriers, which is desirable for efficient photocatalytic CO2 reduction into high-value-added chemical feedstocks. Herein, BiOI flake supported on CuBi2O4 rod (CBO/BOI) with oxygen vacancy was in-situ developed. The CBO/BOI composite demonstrated superior photocatalytic performance for CO2 reduction with H2O vapor compared with those of the individual components. Notably, the product of CO2 reduction changed from CO/CH4 to exclusively CH4 by modulating oxygen vacancies. The CH4 and O2 yields of the optimal CBO/BOI-07 catalyst were 121.7 and 232.6 μmol/gcat/h under visible light illumination, with an apparent quantum yield of 2.25% at 405 nm. The S-scheme charge transfer mode at the CBO/BOI interface was demonstrated through in-situ XPS analysis and theoretical simulations. Furthermore, the presence of oxygen vacancy was found to significantly influence the adsorptive behavior of *CO intermediates, which is crucial for selective conversion of CO2 to CH4. Based on the in-situ Fourier transform infrared spectroscopy and adsorption studies, the reaction mechanism of photocatalytic CO2 reduction was speculated and experimentally validated.