Direct visualisation of metal-defect cooperative catalysis in Ru-doped defective MOF-808

Improving the efficiency of catalytic materials is vital to the chemical and energy industries. Constructing neighbouring active sites in metal-organic framework (MOF) materials for cooperative catalysis is a promising way to achieve the above goal. However, it is difficult to fine-tune active sites at the atomic level due to the challenge of visualising their local structures and their interaction with substrates. In this article, we report the direct visualisation of metal and defect active sites and binding of the phenol substrate in Ru-doped defective MOF-808. X-ray absorption spectroscopy, X-ray pair distribution function analysis, X-ray powder diffraction, and infrared spectroscopy reveal that the enhanced selective hydrogenation originates from the specific adsorption geometry of phenol over 7-centred Ru clusters and hydroxyl or water of defect sites. This mechanism also well explains the high catalytic activity in CO2 reduction. This work represents the first example of structural elucidation of metal-defect cooperative catalysis in MOFs and will lead to the rational design of new superactive MOF catalysts. Metal-defect cooperative catalysis in Ru-doped defective MOF-808 is directly visualised via combined XAS, XPDF, XRD, and IR analysis.