Catalysis and Applications of Gold Nanoparticles

摘要

Historically, gold has been regarded to be catalytically inert, but in recent times it has been shown that it becomes active when stabilized in the form of nanoparticles on metal oxide supports. These supported Au catalysts show remarkable activity in a variety of structure sensitive reactions such as low-temperature CO oxidation and propylene epoxidation. In CO oxidation, Au displays unusual features such as very low apparent activation energy and activity enhancement by moisture. A comprehensive mechanism for CO oxidation is discussed over a wide span of temperature ranging from 90 K to 400 K. When properly prepared by coprecipitation or deposition-precipitation, Au particles adopt hemispherical shapes and the perimeter interfaces around the particles act as reaction sites. CO probably adsorbs on the edge and step sites of Au surfaces and O_2 adsorbs on the support surfaces. Both then react in the interface region. The ongoing and future applications of supported Au catalysts are presented together with future R&D challenges.