A dual Z-scheme heterojunction Cu-CuTCPP/Cu₂O/CoAl-LDH for photocatalytic CO₂ reduction to C1 and C2 products

In this research, a ternary Cu-CuTCPP/Cu₂O/CoAl-LDH composite with a dual Z-scheme heterostructure was fabricated based on a Cu₂O photocatalyst and applied in photocatalytic CO₂ reduction. The physicochemical properties of the prepared catalysts and the possible reaction mechanism in CO₂ reduction were analyzed and studied by various characterization methods. The activity of CO₂ reduction significantly increased, especially forming C2 products. The optimal yield of C₂H₄ and C₂H₆ reached 1.56 and 1.92 μmol g^-1 h^-1 respectively, which was 14.45 and 17.45 times that from using the Cu₂O monomer. In addition, the selectivity of C2 products reached 37.4%. The satisfactory C2 yield was mainly due to the fact that Cu¹⁺₂(COO)₃ nodes in Cu-CuTCPP contained adjacent Cu sites, which effectively promoted the C-C coupling reaction. Moreover, the dual Z-scheme heterojunction stimulated the separation of photogenerated electron-hole pairs and diminished the recombination rate. This work contributes to the development of novel photocatalysts with a dual Z-scheme heterojunction and facilitates the generation of valuable C2 products.