Na-mediated carbon nitride realizing CO2 photoreduction with selectivity modulation

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 photogenerated 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°C (NaCN-550) is 371.2 μmol g^-1 h^-1, which is 58.9 times more than that of the monomer g-C₃N₄. By means of theoretical calculations and experiments including in situ fourier transform infrared spectroscopy, 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.