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.