Construction of TiO2 nanosheets/tetra (4-carboxyphenyl) porphyrin hybrids for efficient visible-light photoreduction of CO2

Abstract

The design and construction of photocatalysts in converting CO2 into value-added chemicals is of significant importance for addressing energy shortages and environmental pollution problems. In this work, a TiO2 nanosheets/tetra (4-carboxyphenyl) porphyrin (TiO2 NSs/TCPP) hybrid for photoreduction of CO2 was developed using a simple self-assemble approach. The TCPP works as the light-harvesting unit to generate light-induced electron-hole pairs, with the connection between the TCPP and TiO2 facilitating the electron injection to the CB of TiO2 as well as inhibiting the recombination of photo-generated electron-hole pairs, then the highly active (0 0 1) facets of TiO2 NSs serve as the reaction sites and efficiently convert the CO2 molecules adsorbed on the surface of the catalysts into CO and CH4 products. The influence of TCPP content on the photocatalytic activity was investigated. Compared to the pristine TiO2 NSs material, the TiO2 NSs/11.5% TCPP composite displayed a much-enhanced photocatalytic CO2 reduction activity, which is equal to 37-fold enhancements in the CO evolution rate. Furthermore, a possible mechanism for CO2 photoreduction over TiO2 NSs/TCPP hybrids is proposed on the basis of the photocatalytic and photo(electro)chemical results.