Fabrication of Z-Scheme CuPc/TiO2 Heterojunctions with Oriented Charge Transport Channels for Efficient Photocatalytic CO2 Reduction

In this study, hollow CuPc nanotubes were synthesized using a one-step solvothermal technique and loaded with TiO2 nanoparticles based on electrostatic interactions thereby overcome the inherent limitations of TiO2. The interfacial electric field formed by electrostatic coupling between CuPc and TiO2 effectively promoted spatial charge separation, as evidenced by a 12-fold enhancement in CO yield compared to pure TiO2 under visible light irradiation. Through energy band analysis and DFT calculations, the Z-type heterojunction mechanism between CuPc and TiO2 has been revealed. This mechanism facilitates the migration of photogenerated electrons from the conduction band of TiO2 to the lowest unoccupied molecular orbital of CuPc, while directing holes to migrate in the opposite direction. This spatial charge separation preserves the electrons’ high reduction capability, allowing them to participate effectively in the CO2 reduction reaction. This work highlights the potential of Z-scheme heterojunctions in designing efficient photocatalysts for CO2 reduction, offering a foundation for future research in advanced photocatalytic materials.