Synergistic catalysis of cluster and atomic copper induced by copper-silica interface in transfer-hydrogenation

Abstract

To data, using strong metal-support interaction (SMSI) effect to improve the catalytic performance of metal catalysts is an important strategy for heterogeneous catalysis, and this effect is basically achieved by using reducible metal oxides. However, the formation of SMSI between metal and inert-support has been so little coverage and remains challenge. In this work, the SMSI effect can be effectively extended to the inert support-metal catalysis system to fabricate a Cu0/Cu-doped SiO2 catalyst with high dispersion and loading (38.5 wt.%) through the interfacial effect of inert silica. In the catalyst, subnanometric composite of Cu cluster and atomic copper (in the configuration of Cu-O-Si) can be consciously formed on the silica interface, and verified by extended X-ray absorption fine structure (EXAFS), in situ X-ray photoelectron spectroscopy (XPS), and high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) characterization. The promoting activity in transfer-hydrogenation by the SMSI effect of Cu-silica interface and the synergistic active roles of cluster and atomic Cu have also been revealed from surface interface structure, catalytic activity, and density functional theory (DFT) theoretical calculation at an atomic level. The subnanometric composite of cluster and atomic copper species can be derived from a facile synthesis strategy of metal-inert support SMSI effect and the realistic active site of Cu-based catalyst can also been identified accurately, thus it will help to expand the application of subnanometric materials in industrial catalysis.