In-situ engineering of metallic bismuth on S-scheme BiOBr/Bi2MoO6 heterostructures with enriched oxygen vacancies for efficient photocatalytic CO2 reduction

Photocatalytic CO₂ reduction to produce high-value-added chemicals is a promising strategy, however, fabricating highly efficient and economical catalysts is a critical challenge. Herein, an in-situ metal Bi engineering strategy during the construction process of double‑bismuth-based S-scheme heterojunctions is developed via a straightforward solvothermal approach. The as-prepared Bi/BiOBr/Bi 2 MoO 6 S-scheme heterojunctions exhibit abundant enriched oxygen vacancies (OVs) and a pronounced Bi surface plasmon resonance (SPR) effect due to a high dispersion of the in-situ formation process, achieving excellent photocatalytic performance of CO 2 -to-CO conversion. Surprisingly, the photocatalytic activity of CO 2 -to-CO over Bi/BiOBr/Bi 2 MoO 6 is up to 71.91 μmol·g −1 ·h −1 , with a high selectivity of 97.04 %. This represents enhancements of 141- and 1.63-fold compared to pure Bi 2 MoO 6 and Bi/BiOBr, respectively. The outstanding photocatalytic CO 2 reduction performance can be ascribed to the synergistic enhancement effects of S-scheme heterostructures, the pronounced Bi SPR effect, and the enriched OVs engineering. Theoretical calculations and in situ spectroscopy analyses unveil that the mechanism of enhanced photocatalytic CO 2 reduction achieved through in-situ metallic Bi and OVs engineering on the S-scheme heterojunction. This meticulous catalyst design provides insights into a novel strategy for the efficient and precise customization of unique S-scheme Bi-based photocatalyst with enriched OVs and Bi SPR effects, opening new avenues for practical photocatalysis applications.