Switching of CO₂ hydrogenation selectivity via chlorine poisoning over Ru/TiO₂ catalyst

It is fascinating to explore the distribution of CO₂ hydrogenation products regulated by heterogeneous catalysts, as both the chemical state of surface metals and structure of the support itself of the supported catalysts may affect the performance of CO₂ hydrogenation. Herein, the complete switching of CO₂ hydrogenation products from CH₄ to CO can be realized by induction of Cl into Ru/TiO₂ catalyst. Density functional theory (DFT) calculations indicated that Cl ions were mainly located on the Ru metal sites of Ru/TiO₂ catalysts. Bader charge analysis and Ru 3p X-ray photoelectron spectra (XPS) results suggested that electrons transferred from Ru to Cl, resulting in the decrease of electron density of Ru. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO₂ hydrogenation and CO adsorption proved that with the increase of the Cl ion content, the adsorption of CO on the catalyst surface was significantly weakened, and resulted in the high CO selectivity. Our work demonstrates the role of Cl ions in regulating the distribution of CO₂ hydrogenation products, and provides new ideas for regulating other catalytic processes.