Near-unity CO₂-to-ethylene photoconversion over low coordination single-atom catalysts

Photocatalytic conversion of carbon dioxide to value-added chemicals, particularly multi-carbon products, offers a promising route toward carbon-neutral cycles. However, achieving high activity and selectivity remains extremely challenging due to the instability of key reaction intermediates and limited C-C coupling efficiency. Herein, we report a low-coordination manganese single-atom catalyst embedded in zinc sulfide (Mn₁-ZnS_v) that enables efficient and selective CO₂-to-C₂₊ conversion. In-situ spectroscopic analyses and density functional theory calculations reveal that sulfur vacancies are created at the Mn single-atom coordination sites and induce the formation of coordination-unsaturated Mn-S₂ configuration. The asymmetric coordination environment of Mn modulates local charge distribution, strengthens *CO adsorption, and promotes *CO and *CHO coupling to form the *COCHO intermediate for efficient C-C coupling. As a result, the Mn₁-ZnS_v catalyst achieved 99.1% selectivity for ethylene with a formation rate of 76.6 μmol g^-1 h^-1. This study highlights the critical role of atomic-level coordination engineering in advancing photocatalytic CO₂-to-C₂₊ conversion.