Synergistic Effect between Rhenium-Zinc Binary Oxides in Catalytic CO₂ Hydrogenation to Methanol

CO₂ hydrogenation to methanol utilizing renewable H₂ offers a promising route for carbon neutrality, but efficient catalysts with synergistic active sites of H₂ and CO₂ remain challenging. Herein, we demonstrate a TiO₂-supported rhenium-zinc binary oxide catalyst that exhibits methanol selectivity up to ca. 70% at a CO₂ conversion of 9.3% and a methanol space-time yield of 529 mg·h^-1·g_cat^-1 at 320 °C and 5 MPa, outperforming ReO_x/TiO₂ and ZnO/TiO₂ catalysts by 5.8 and 2.3 times, respectively. Kinetics analysis combined with structural characterization supports the synergistic effect between dual ReO_x and ZnO sites for enhanced performance. Strong Re-Zn interactions generate ReO_x sites that are responsible for promoted H₂ activation, whereas the highly dispersed, partially reduced ZnO strengthens CO₂ adsorption and activation. The activation of CO₂ and H₂ is decoupled on distinct sites yet coupled via efficient hydrogen supply, thereby accelerating hydrogenation of CO₂-derived intermediates. In situ diffuse reflectance infrared Fourier transform spectroscopy reveals a preferred formate pathway, featuring the evolution of b-CO₃* to HCOO* and subsequently to H₃CO*. This work highlights the synergistic effect between dual oxide sites in promoting selective CO₂ conversion to value-added chemicals.