Enhanced and selective photocatalytic reduction of CO2 to CH4 using a Pt-loaded CuPc/g-C3N4 Z-scheme heterojunction catalyst

In this study, a novel Pt-loaded CuPc/g-C3N4 (PtCuCN) composite was synthesized for the selective photocatalytic reduction of CO2 to CH4 under visible light. The PtCuCN catalyst achieved a CH4 yield of 39.8 μmol g−1 h−1, significantly outperforming bulk g–C3N4 and CuPc alone by factors of 2.5 and 3.1, respectively, with a high selectivity of 90%. In comparison with other commonly studied photocatalysts, such as g–C3N4–based catalysts, the PtCuCN composite exhibited superior CH4 yield and product selectivity, demonstrating its potential as a more efficient photocatalyst for CO2 reduction. X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations, and in-situ infrared (IR) analysis revealed that the Pt0 species effectively lower the activation energy for CH4 formation, while CuPc extends the light absorption range and enhances charge separation. The combined effects of these components in a Z-scheme heterojunction provide new insights into designing highly selective CO2-to-CH4 photocatalysts. This work demonstrates the potential of PtCuCN as a highly efficient and stable catalyst for CO2 reduction to CH4 under visible light.