Unraveling phosphate anion modification on Pt/TiO2 catalysts for specific conversion in CO2 hydrogenation

Anion modification offers a promising approach for the specific conversion of reaction substrates in catalytic processes. In this study, we synthesized Pt-based metal nanocatalysts on a TiO 2 support and modified them with PO 4 3- anions, thereby achieving a complete shift in CO 2 hydrogenation products from CO to CH 4 . The original Pt-P 0 /TiO 2 catalyst exhibited a low degree of CO 2 conversion (4.5%), and the hydrogenation products comprised primarily CO. In contrast, the Pt-P 3 /TiO 2 catalyst modified with PO 4 3- anions exhibited a 5.2-fold increase in the degree of CO 2 conversion (23.2%) and excellent methane selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and CO-temperature-programmed desorption (TPD) characterization revealed distinct reaction pathways. Notably, the desorption of CO intermediates predominated for the Pt-P 0 /TiO 2 catalyst, whereas further hydrogenation of CO prevailed on the surface of the Pt-P 3 /TiO 2 catalyst. The results of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations indicated that PO 4 3- anions adsorbed preferentially at Pt metal sites, modulating the surface electronic properties of the Pt metal and its adsorption and desorption behaviours towards CO, thereby increasing the CO 2 conversion efficiency and causing a shift in hydrogenation products. This work provide valuable insights for designing high-performance catalysts for ensuring sustainable CO 2 conversion.