The structure of Pd-functionalized UiO-67 during CO₂ hydrogenation

The detailed evolution of the local atomic and electronic structure of palladium nanoparticles (NPs) embedded in Zr-based metal-organic frameworks (MOFs) UiO-67 is presented. The samples were employed for CO2 hydrogenation under different temperatures and at total pressures of 1 or 8 bar. The effects of exposure to the reactive atmosphere and reaction products on the structure of MOFs and Pd NPs were monitored in operando mode by simultaneous X-ray diffraction and X-ray absorption spectroscopy measurements. Advanced analysis of large experimental datasets supported by theoretical simulations revealed the formation of mixed carbide and hydride phases of palladium and the adsorption of CO species as reaction intermediates at the surface of Pd NPs under the reaction conditions. According to available information, the observation of the Pd/Zr interface and its association with methanol formation was first obtained in this work for Pd-Zr-MOFs materials.