g-C3N4/PP-CDs Heterostructure with Lewis acidity and alkalinity promoted photocatalytic CO2 reduction to CH3OH

It is expected that photocatalytic reduction of carbon dioxide to produce valuable chemicals play an important role in achieving carbon neutrality goals. Photogenerated electron-hole separation efficiency is one of the factors determining photocatalytic activity. Herein, carbon dots with oxygen-containing protoporphyrin (PP-CDs) were loaded on g-C₃N₄ nanosheets form a heterostructure by a facile mechanical stirring method. The g-C₃N₄/PP-CDs-3 has a conduction band potential of −1.31 eV and a bandgap of 2.51 eV, in the absence of any added photosensitizer and sacrificial agent under illumination, the methanol yield achieved 357.5 μmol·g⁻¹·h⁻¹, which is 2.2 times than that of g-C₃N₄ (162.1 μmol·g⁻¹·h⁻¹), after four cycles, the photocatalytic activity remained unchanged. Based on the experimental and characterizations results, it is indicated that the photocatalytic reduction performance of CO₂ to methanol was improved mainly attributed to the visible light absorption and the high Lewis acidity and alkalinity. Furthermore, the steric hindrance was provided for photogenerated electron-hole recombination due to the recombination of carbon points his work offers a promising strategy for constructing efficient photocatalysts to achieve CO₂ to CH₃OH transformation.