Amino group promoted photoelectrocatalytic CO2 reduction activity observed in mixed-linker Cu-based metal-organic frameworks

The absorption of visible light of mixed-linker metal-organic frameworks can be enhanced by adding organic ligands to be present as reaction sites. In this work, through the introduction of an amino-functionalized organic ligand (NH2BDC, BDC = 1, 4-benzenedicarboxylate) into the structure of CuBDC, dual-ligand Cu-based MOF (CuBDC-xNH(2)/CF, x represents the molar ratio of NH2BDC) was successfully synthesized on copper foam (CF). The photoelectrocatalytic CO2 reduction performance of all samples was explored when increasing amounts of NH2BDC linkers (0%, 5%, 10%, 20%, 50%, and 100%) are incorporated in the framework. The highest Faradaic efficiency of CO (51.5%) was achieved when the molar ratio of NH2BDC was 10%. NH2BDC can effectively improve the visible light absorption ability of MOFs. And both terephthalic acid (H2BDC) and NH2BDC are coordinated with Cu-O clusters, which contribute to the generation and separation of charges. At the same time, the amino functional group can effectively adsorb the CO2 molecules as a basic site. The synergistic effect improves the Faradaic efficiency of the reduction products.