Photocatalytic carbon dioxide (CO2) reduction (PCCR) is a promising method for converting CO2 into high-value multicarbon products using solar energy. However, the yield and selectivity of desired products remain low. Here we report the production of ethanol with a yield of \(1.4\,\text{mmol}\,{\text{g}}_{\mathrm{cat}}^{-1}\,{\text{h}}^{-1}\) and a selectivity of 93.7% using simulated solar-driven PCCR, over chiral mesostructured copper-doped In2S3 photocatalysts, without any additives. Chirality-induced spin polarization in the photocatalyst promotes the formation and stabilization of triplet OCCO intermediates. Subsequently, the reactive Cu–In dual sites on the catalyst surface efficiently convert these triplet OCCO intermediates into chemisorbed *OCCO and *OCCOH intermediates. This conversion facilitates an efficient C–C coupling process, leading to ethanol production with minimized C1 by-products. Our findings demonstrate that high selectivity and productivity in PCCR can be achieved by combining chirality-induced spin polarization with surface reactive sites. The importance of enhancing overall C2 intermediates for multicarbon PCCR is also highlighted, expanding our understanding of the mechanisms of photocatalytic CO2 reduction.
