NEW STRATEGIES TO ENHANCE THE STABILITY AND ACTIVITY OF SINGLE-ATOM CATALYSTS

Abstract

Single-atom catalysts (SACs) with isolated metal atoms immobilized on supports have emerged as a new frontier in catalysis. However, the catalytic performance of SACs still needs to be improved. In this thesis, we propose three strategies including steric confinement, ligand modification, and electrostatic stabilization to modify SACs. In the first approach, single Pt atoms were confined into the matrix of supports using the high-temperature flame spray pyrolysis. The formed Pt SACs showed higher activity than those synthesized by the conventional wet impregnation method in high-temperature applications such as methane combustion due to the improved redox ability. Besides, the ligand modification was proved to be able to tune the activity and selectivity of Pd SACs in the semi-hydrogenation reactions. Furthermore, we developed the concept of ionic liquids stabilized SACs, where an electrical double layer of ionic liquids surrounding single-atom species provides electrostatic stabilization against the aggregation and leaching of single-atom metals.