Selective CO2 photoreduction into C2 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 C2 products. As an example, FeCoS2 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 FeCoS2 atomic layers exhibit C2 H4 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.
Keywords: CO2 Photoreduction; C−C Coupling; Partial Oxidation; Photocatalysis; Triatomic Sites.
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