Inverse-type CoOx-TiO2 catalysts for the Energy-Efficient Thermo-Photo Valorization of CO2

In this research, composite catalysts based on mixtures of titanium and cobalt oxides were synthesized and tested in the thermo-photo reduction of carbon dioxide. The cobalt loading varied between 2% and 8 M %, providing an outstanding activity in the selective production of carbon monoxide through the reverse water gas reaction. The sample doped with 4% Co optimized catalytic performance, with an excess over the photo and thermo alone processes above 27 % and an energy efficiency of 1.1 %. These values indicate that the sample displays the top performance reported so far. A physico-chemical characterization of the catalysts was also carried out showing that nearly amorphous cobalt (II) oxide entities are embedded within nanocrystalline anatase nanoplatelets within an inverse-type configuration. The use of in-situ infrared provides conclusive evidence that the promotion of the catalytic performance under dual excitation is intimately linked with the formation and evolution of formate-type species at the catalyst surface. A novel dual-excitation catalytic process using novel composite CoOx-TiO2 catalysts would open new ways for the energy-efficient elimination and valorization of carbon dioxide. © 2023 The Authors