Visible-Light-Driven Photoreduction of CO2 to CH4 over N,O,P-Containing Covalent Organic Polymer Submicrospheres

Abstract

Solar-energy-driven photoreduction of CO2 to hydrocarbon fuels is an interesting and challenging topic, which generally requires photocatalysts with the capability to capture and photoreduce CO2 simultaneously. Herein, we demonstrate that a N,O,P-containing covalent organic polymer (NOP-COP) prepared via condensation of hexachlorocyclotriphosphazene with barbituric acid can capture CO2 and further photocatalyze its reduction to CH4 under visible-light irradiation. The characterization information indicates that the incorporation of phosphorus in the skeleton of NOP-COP promoted the absorption of visible light and improved the lifetime of the photoinduced carriers. As a result, NOP-COP exhibited enhanced efficiency for photoreduction of CO2 compared with the N,O-containing polymer, affording CH4 as the sole carbonaceous product with a rate of 22.5 μmol gcat–1 h–1 and selectivity over 90%. This work provides insight into designing and fabricating polymeric photocatalysts for CO2 photoreduction to fuels.