Abstract:  

Supported metal nanoparticles are among the most important catalysts for many practical reactions. The catalytic performance strongly depends on the size, composition, and structure of the metal nanoparticles as well as the underlying support. Conventional synthesis methods including impregnation, ion exchange, and deposition-precipitation have been used to control and tune these factors, to establish structure-performance relationships, and to develop better catalysts. Meanwhile, the stability of metal nanoparticles against sintering has been improved by the application of protective layers, such as polymers and oxides that encapsulate the metal particle. This often leads to decreased catalytic activity due to a lack of precise control over the thickness of the protective layer.

A promising new method of catalyst synthesis is atomic layer deposition (ALD). ALD is a variation on chemical vapor deposition wherein metals, oxides, and other materials are deposited on surfaces via a sequence (usually binary) of self-limiting reactions. The self-limiting character of the reactions makes it possible to achieve uniform deposits on high-surface-area porous solids. Hence, design and synthesis of advanced catalysts at the nanoscale becomes possible through precise control over the structure and composition of the underlying support, the catalytic active sites, and the protective layer. In this presentation, I will describe the application of ALD to synthesize highly uniform supported metal catalysts and to apply oxide overcoats with atomically-precise thickness control for stabilization of metal nanoparticles while preserving their catalytic function.