Reinforced Photogenerated Electrons in Few-Layer C3N5 for Enhanced Catalytic NO Oxidation and CO2 Reduction

Two-dimensional (2D) polymer carbon nitrides are cutting-edge environment-friendly photocatalysts relying on their extraordinary properties of cost-effectiveness, low toxicity, visible-light response, and chemical stability. Here, we report few-layer C3N5 with a thickness of around 1.2 nm as a case study, whose photogenerated carriers' dynamics achieve a significant increase proven by the transient diffuse reflectance spectra. In addition, few-layer C3N5 changes to mainly exhibit the behavior of photogenerated electrons in comparison to bulk C3N5, whose lifetime extends 3.25-fold and is even 3.72-fold of that for g-C3N4. Density functional theory calculations further verify the superior adsorption and activation of small molecules of NO, O2, and CO2 over few-layer C3N5. The abovementioned unique intrinsic properties endow few-layer C3N5 with a significantly enhanced photocatalytic capability in air NO oxidation and CO2 reduction with respect to bulk C3N5 and traditional C3N4. This work may help in developing efficient 2D metal-free catalysts for photocatalytic applications.