Synergistic Crystal Facet Engineering and Bi Incorporation in ZnIn2S4 for Enhanced Photocatalytic CO2 Reduction

Crystal facet engineering and Bi incorporation are effective strategies to enhance photocatalytic CO2 reduction, yet their synergistic effects in ZnIn2S4 remain underexplored. Herein, Bi-modified ZnIn2S4 (Bi-ZIS) with a preferentially exposed (006) plane and enriched sulfur vacancies (VS) was constructed via a combined crystal facet engineering and Bi-doping strategy. The optimized 5% Bi-ZIS exhibited the highest photocatalytic performance, producing CO and CH4 yields of 242 and 45 μmol g–1 under visible-light irradiation for 3 h. Comprehensive characterizations revealed that the exposed (006) plane, sulfur vacancies, and Bi nanoparticles collectively promoted light harvesting, charge separation, and CO2 activation. In situ DRIFTS confirmed the presence of key intermediates (*COOH, CHO*, CH3O*), and DFT calculations verified electronic-structure modulation induced by Bi doping. This work provides an efficient strategy for rational design of ZnIn2S4-based photocatalysts via synergistic crystal facet and defect engineering for solar-driven CO2 conversion.