Selective CO2‐to‐C2H4 Photoconversion Enabled by Oxygen‐Mediated Triatomic Sites in Partially Oxidized Bimetallic Sulfide

Abstract Selective CO 2 photoreduction into C 2 fuels under mild conditions suffers from low product yield and poor selectivity owing to the kinetic challenge of C−C coupling. Here, triatomic sites are introduced into bimetallic sulfide to promote C−C coupling for selectively forming C 2 products. As an example, FeCoS 2 atomic layers with different oxidation degrees are first synthesized, demonstrated by X‐ray photoelectron spectroscopy and X‐ray absorption near edge spectroscopy spectra. Both experiment and theoretical calculation verify more charges aggregate around the introduced oxygen atom, which enables the original Co−Fe dual sites to turn into Co−O−Fe triatomic sites, thus promoting C−C coupling of double *COOH intermediates. Accordingly, the mildly oxidized FeCoS 2 atomic layers exhibit C 2 H 4 formation rate of 20.1 μmol g −1 h −1 , with the product selectivity and electron selectivity of 82.9 % and 96.7 %, outperforming most previously reported photocatalysts under similar conditions.