Decagram-scale synthesis of heterometallic Ag/Ti cluster as sustainable catalyst for selective oxidation of sulfides

Abstract

Atomically precise heterometallic clusters constitute a new family of model catalysts for understanding the fundamental catalysis process widely occurred in supported nanocatalysts, however, their syntheses and structure/composition modulations are nonetheless daunting challenges. Herein, three novel heterometallic Ag/Ti clusters with different Ag-doping ratios, Ag4Ti14, Ag4Ti6 and Ag4Ti2, have been readily synthesized in decagram-scale quantities through ligand engineering strategy. Thereinto, Ag4Ti2 can be efficiently prepared within 3 h in a quite high yield > 95 %. More remarkably, Ag4Ti2 shows unprecedented catalytic activity (>90 % conversion within 1 min) and selectivity (nearly 100 %) towards oxidation of thioethers with a wide substrate scope even including notorious 2-chloroethyl ethyl sulfide (CEES) at room temperature (turnover frequency = 11,880 h−1), which is mainly attributed to its full-surface-exposure-doping Ag atoms (affinity for binding of substrate) on TiO support and their cooperativity, whereas the other two are not the same case. Moreover, the Ag4Ti2 is highly robust in catalysis process and can be readily recovered and reused at least six cycles without observable loss of activity and selectivity, enabling this cluster hold great promise in industrial applications. This work not only establishes a general method to scale-up synthesis of Ag/Ti clusters but also provides an atom-precise model catalyst to understand the structure–property correlations of real-world conventional nanocatalysts such as silver doped-TiO2 nanoparticles.