Na-mediated carbon nitride realizing CO2 photoreduction with selectivity modulation

Abstract

The depressed directional separation of photogenerated carriers and weak CO2 adsorption/activation activity are the main factors hampering the development of artificial photosynthesis. Herein, Na ions are embedded in graphitic carbon nitride (g-C3N4) to achieve directional migration of the photo-generated electrons to Na sites, while the electron-rich Na sites enhance CO2 adsorption and activation. Na/g-C3N4 (NaCN) shows improved photocatalytic reduction activity of CO2 to CO and CH4, and under simulated sunlight irradiation, the CO yield of NaCN synthesized by embedding Na at 550 ℃ (NaCN-550) is 371.2 μmol g−1h−1, which is 58.9 times bigger than that of the monomer g-C3N4. By means of theoretical calculations and experiments including in situ FTIR, the mechanism is investigated. This strategy which improves carrier separation and reduces the energy barrier at the same time is important to the development of artificial photosynthesis.