Studying bimetals copper-indium for enhancing PCN photocatalytic CO₂ reduction activity and selectivity mechanism

In this work, a bimetallic indium-copper-doped atomically dispersed Cu-In-PCN photocatalyst was prepared by thermal polymerization, and it exhibits remarkable photocatalytic CO₂ reduction activity with CO yield of 113.56 µmol g⁻¹ and a selectivity nearly 96 %. Additionally, experimental investigations and DFT calculations reveal the mechanisms underpinning the high performance of Cu-In-PCN catalyst, that Cu 3d and In 5p orbitals contribute to the band composition of Cu-In-PCN and reduced the bandgap, the electrons from PCN transfer to copper active sites and increasing the electron density for CO₂ reduction. Furthermore, the Cu-In bimetallic lowered the free energy of COOH* intermediate, which more easily conversion to CO via dehydroxylation than PCN, Cu-PCN, and In-PCN. In situ FTIR show that the COOH* is the key intermediate in the photocatalytic reduction of CO₂ to CO. This work makes up for the current shortcomings of using bimetallic-doped PCN for photocatalytic CO₂ with low selectivity and unclear mechanism.