Enhancing CO2 photoreduction to C2H4 via vacancy and interfacial bond construction

• Constructed S-scheme heterojunction enabling directional separation of photogenerated carriers. • Engineered interfacial Bi-S-In bridges accelerating charge transfer kinetics. • S vacancies enhance visible-light harvesting while creating electron-rich domains for CO 2 adsorption/activation. • Achieved selective CO 2 -to-C 2 H 4 conversion via precisely tailored Bi 2 S 3 /ZnIn 2 S 4 heterostructure. Establishing interfacial bonds and vacancies plays a crucial role in achieving efficient photocatalytic CO 2 reduction. However, precisely controlling the directional and robust electron transfer processes remains a significant challenge. In this study, we constructed a Bi 2 S 3 /ZnIn 2 S 4 S-scheme heterojunction photocatalyst featuring sulfur vacancies (S v ) and interfacial Bi-S-In bonds via a simple hydrothermal method. Experimental and theoretical results demonstrate that the S-scheme electron transfer effectively suppresses carrier recombination while maintaining strong redox capabilities. The interfacial Bi-S-In bonds accelerate charge transport through atomic-level channels, acting as electron bridges to facilitate charge transfer and optimize electron density distribution, thereby further enhancing carrier separation efficiency. Additionally, the introduced S v not only improves visible-light absorption but also promotes CO 2 adsorption and activation through electron-rich sites. Simultaneously, S v reduces the C–C coupling energy barrier by stabilizing key OCCO intermediates, guiding the reaction pathway toward C 2 H 4 production. The optimized 40 %-Bi 2 S 3 /ZnIn 2 S 4 exhibited superior photocatalytic performance under visible light, achieving a C 2 H 4 production rate of 56.4 μmol g – 1h – 1 with 96 % selectivity and excellent cycling stability. This study provides a novel strategy for directional CO 2 conversion into high-value multi-carbon products through synergistic design of S v , heterojunctions, and interfacial chemical bonds, offering significant scientific implications for advancing solar-driven carbon cycle technologies.