Surface Organometallic Chemistry as a Versatile Strategy for Synthesizing Supported Bimetallic Cluster Catalysts

Abstract

Bimetallic clusters anchored on thermally stable and high-surface-area supports have gained a wide range of applications in heterogeneous catalysis. Compared to monometallic clusters or large bimetallic nanoparticles, bimetallic clusters show unprecedented catalytic performances due to the modulated electronic and geometric effects arising from the high fraction of surface unsaturated–coordinated metallic atoms and the synergistic effects between two constituting metals. However, even after more than 60 years of efforts, the controlled synthesis of homogeneously distributed bimetallic clusters with well-alloyed structure between two constituting metals remains a tremendous challenge so far. Herein, we present a versatile strategy based on the surface organometallic chemistry concept for synthesizing supported bimetallic cluster catalysts, which is achieved via the hydrogenation of a so-called “double surface organometallic complex”. The cooperative decomposition of two surface organometallic fragments in the double surface organometallic complex and their strong interaction with the support enable the formation of well-alloyed bimetallic clusters uniformly dispersed at the surfaces of different supports. This approach can serve as a platform technique for producing a variety of bimetallic clusters with varied compositions on a wide range of supports, such as Al2O3, TiO2, and zeolite. The resulting bimetallic cluster catalysts exhibit remarkably enhanced catalytic performance in benzene hydrogenation as compared to their monometallic counterparts because of highly exposed surface atoms and synergistic effects between constituting metals.