Research on 2D/2D Au/g-C3N4 electron donor/acceptor strategy for highly efficient CO2 photoreduction

Abstract

Utilizing CO2 photoreduction technology to convert CO2 into carbon-based gaseous fuels represented an effective strategy for maintaining sustainable development on Earth. Addressing the issue of poor electron separation efficiency in pure g-C3N4, an innovative approach was taken to construct a two-dimensional/two-dimensional (2D/2D) structure using Au nanosheets (Au NSs) combined with g-C3N4 nanosheets (CN NSs) for CO2 photoreduction. The CO and CH4 yields converted by CO2 photoreduction over Au/CN composite (15AC) with optimized proportion were about 44.76 and 32.12 μmol g−1 h−1 under UV–Vis light irradiation, respectively. Photoelectrochemical experiments revealed that the modification of CN NSs with Au NSs significantly improved the separation efficiency of photogenerated carriers at the 2D/2D interface, while enhancing the CO2 adsorption ability of pure CN NSs. Density Functional Theory (DFT) calculations were employed to analyze the electron transfer pathways at the 15AC interface and the formation of a built-in electric field, which concurrently confirmed that the electron donor–acceptor relationship accelerated the transfer of photogenerated electrons from CN NSs to Au NSs. In-situ FTIR and 13CO2 isotope calibration experiment were utilized to probe the CO2 photoreduction process. Finally, the possible electron donor–acceptor enhanced mechanism at the 2D/2D Au/CN interface for enhancing the CO2 photoreduction reaction were discussed.