Enhanced Photothermal Catalytic Conversion of CO₂ into CO Using Uniformly Dispersed Pt on Mesoporous TiO₂

The photothermal catalytic conversion of CO2 into value-added chemicals is of great significance for realizing the goal of carbon neutralization. However, these catalysts have problems such as an insignificant photothermal effect and high recombination of photogenerated carriers. Here, porous TiO2 was prepared by hydrothermal crystallization and topological conversion of metal–organic frameworks (MOFs), and loaded with highly dispersed Pt catalysts to realize an efficient photothermal catalytic reverse water-gas shift (RWGS) reaction. N2-adsorption results showed that the as-prepared Pt/TiO2 catalysts had an abundant mesoporous structure, thus contributing to the rapid diffusion of reactants and light transport. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results showed that Pt was uniformly dispersed on the catalyst surface with an average particle size of 2.06 nm. H2-TPR profiles showed that the Pt/TiO2 catalyst had strong metal–support interactions, CO2-TPD showed its strong CO2 adsorption capacity, and CO-TPD showed its weak CO adsorption strength. In situ X-ray photoelectron spectroscopy (XPS) showed that the electron cloud density on the Pt surface further increased under light illumination, which contributed to the activation and dissociation of H2. In addition, the Pt/TiO2 catalyst had a narrow band gap width and sufficiently low reduction potential, and its excellent photothermal and photovoltaic properties ensured efficient performance in the photothermal RWGS reaction. The Pt/TiO2 catalysts showed a high CO2 conversion of 29.8%, a product CO selectivity higher than 99.6%, and a stability of more than 3000 min at 350 °C, with a light intensity of 1.2 W cm–2 and a GHSV of 36,000 mL gcat–1 h–1.