Electron gathering at violet phosphorene-Ag interface for photoreduction of CO2 to ethylene

Abstract

Selective photoreduction of CO2 into ethylene is desirable but stays challenging due to easy desorption of primary reduction product CO. Herein, violet phosphorene nanosheets (VPNS) are for the first time demonstrated to be effective CO2 photoreduction catalysts to yield ethylene. Photoelectron was found to transfer from VPNS to co-catalyst Ag and aggregated on VPNS-Ag interface to enhance CO2 and CO* adsorption, and further lower the reduction energy barrier to yield ethylene, which was confirmed by in-situ diffuse reflectance infrared Fourier-transform, CO stripping voltammetry, CO reduction experiments, and density functional theory calculations. CO2 is reduced into COOH* and automatically transformed into CO* on VPNS-Ag surface, then protonized into CHO* with a low barrier of 0.64 eV and automatically coupled into COCHO* to yield ethylene. Only ethylene was detected from CO2 photoreduction with a yield of 10.34 μmol g−1 h−1 without any hole-sacrificial agent, much higher than most reported photocatalysts.