(188e) Single Pt Atoms Dispersed on Exsolved Nano-Socket Catalysts for Metallic Active Sites and Robust Stability

Platinum group metals possess unbeatable positions in heterogeneous catalysis because of their order-of-magnitude higher reactivity compared to other transition metals. The high prices of platinum group metals, however, have hindered their applications. A variety of synthesis techniques has been, therefore, developed for efficient utilization of the expensive precious metals. Single-atom catalysts (SACs) are an important milestone in this field, and ideally 100% of loaded metals can be utilized for active sites. In many cases, however, loaded metals are oxidic rather than metallic, leading to unexpected catalytic properties, different from those in nanoparticle catalysts. Low stability of SACs due to agglomeration of loaded metals is also one of important disadvantages of conventional SACs. Here, we proposed a novel class of SACs, namely nano-socket single atom (NSA) catalysts, that maximizes the utilization of Pt atoms while maintaining their metallic state. NSA catalysts are consisted of cerium oxide with exsolved transition metal nanoparticles (nano-socket) and single Pt atoms selectively dispersed on the surface and interface of the exsolved nanoparticles. DFT calculations were performed to select proper transition metal dopant that is facile to induce exsolution process and provides strong interaction with Pt atoms. EXAFS, XRD, XPS, in-situ DRIFT analyses were carried out to identify the structures of synthesized NSA catalysts. Genetic algorithm with a state-of-the-art neural network potential was also performed to theoretically explore the globally optimized structure of NSA catalysts. The NSA catalysts outperformed Pt nanoparticle catalysts in CO oxidation reaction and showed robust stability because of retained initial active site structures. Not only CO oxidation reaction, but NSA catalysts are also widely applicable to high temperature reactions.