Synergistic S–O Coordination in Subnanometer Indium Oxysulfide Coils for CO₂ Photoreduction

Photocatalytic CO₂ reduction offers a green strategy to alleviate climate change and address the energy crisis. In this work, indium oxysulfide subnanocoils with a thickness of 0.9 nm were successfully synthesized via a facile solvothermal method. Adjusting the sulfur content not only modulates the band structure and energy level positions but also enables precise control over the morphology of the as-prepared products. The optimized indium oxysulfide subnanocoils exhibit excellent photocatalytic activity for CO₂ reduction, with a CO evolution rate of 61.731 μmol h^–1 g^–1, which ranks among the best performances for indium-based materials reported to date. The enhancement of photocatalytic performance can be attributed to the exceptionally high surface atomic exposure ratio of the unique subnanometer coiled structure. Meanwhile, the sulfur substitution-induced S–O coordination significantly reduces the average valence state of indium, narrows the band gap, and improves the reduction capability of photogenerated electrons. This study provides a feasible approach for the development of high-performance subnanoscale photocatalysts for CO₂ reduction.