RGO modified R-CeO2/g-C3N4 multi-interface contact S-scheme photocatalyst for efficient CO2 photoreduction

Abstract

Construction of multi-interface contact step-scheme (S-scheme) photocatalyst is a promising pathway to achieve high-electron transfer efficiency for photocatalytic CO2 reduction. In this paper, g-C3N4 nanosheets were selected as the main photocatalyst, rod-like CeO2 (R-CeO2) with unique Ce4+→Ce3+ conversion property and rGO were loaded on the g-C3N4 surface to construct 2D-1D-2D sandwich photocatalyst. The yields of CO and CH4 were about 63.18 and 32.67 μmol/g after 4 h when the rGO/R-CeO2/g-C3N4 was used as catalyst, which were about 4 and 6 times higher than that of pure CN, respectively. Cyclic experiments proved that the composite had excellent photocatalytic and material stability. Photoelectrochemical tests showed that the construction of S-scheme electron transfer model and the introduction of rGO can great enhance the electron transmission and separation of photogenerated electron-hole pairs. CO2 adsorption test identified that the loading of R-CeO2 and rGO obviously enhanced the CO2 adsorption ability of pure g-C3N4. Density functional theory (DFT) calculations used to analyze the electron transfer path and the formation of the build-in electric field at the semiconductor interface. In-situ FTIR and 13CO2 element-tracer detection carried out to research the process of CO2 photoreduction. A possible multi-interface contact S-scheme electron transfer mechanism for enhanced CO2 photoreduction activity has been discussed.