CdS-based ternary composite material for high-efficiency photocatalytic CO2 reduction via a cascade electron transfer

Abstract

CdS conductor has a suitable band gap (~2.4 eV), and the energy band position is conducive to photocatalytic CO2 reduction. However, its photocatalytic efficiency is highly confined by its unfavored carrier transfer. In this study, a moderately in-situ growth method is harnessed to insert commercial TiO2 particles (P25) into the CdS grains in the first place, and the resulted CdS-P25 composite is further integrated with to a mixed-ligand-based metal organic framework (MOF), CuTCPP⊂UiO-66 (CTU), which is structure-analogous to regular UiO-66 MOF but with visible light response thanks to the involvement of copper(II) tetra(4-carboxyphenyl) porphyrin (CuTCPP) ligand. The eventually attained ternary composite (CTU/CdS-P25) by solvothermal approach presents a broadened light absorption and an impressive delivery for photo-induced carriers. The light-driven catalytic assessment of CTU/CdS-P25 for CO2 reduction furnishes the CO production rate as great as 2.38 μmol·h−1, as much as 3.9 and 8.8 times that of UiO/CdS-P25 and CdS-P25, respectively. According to the value determination of band edge for each component of the ternary composite, we proposed that the established heterojunction facilitates a cascade electron transfer mode within the structure, which highly suppresses the adverse recombination of carriers and thereafter significantly enhances the photocatalytic behavior. Our work provides an effective perspective for the melioration of CdS semiconductor.