Design of novel structured gold nanocatalysts

Small gold nanoparticles dispersed on certain oxide supports exhibit unprecedented catalytic activities in low-temperature CO oxidation, and gold catalysts show a great potential for selective oxidation or hydrogenation of organic substrates. Nevertheless, most gold catalysts (e.g., Au/TiO₂, Au/Al₂O₃, Au/Fe₂O₃, Au/SiO ₂, Au/CeO₂) have been prepared by loading gold on unmodified or modified solid supports through traditional synthesis methodologies (e.g., deposition precipitation, wet impregnation), therefore having simple metal-on-support structures and metal-support interactions. The current Perspective highlights some recent progress in the design of novel structured gold nanocatalysts, including unsupported or supported core-shell or yolk-shell structures, gold nanoparticles encapsulated in an inorganic matrix, postmodified gold catalysts, gold-based alloy catalysts, and gold catalysts with additional interfacial sites (or metal oxide components) carried to supports or formed in situ on supports. The objective of most of these studies was to demonstrate synthetic protocols by testing the catalytic performance of the prepared catalysts in simple probe reactions, and the focus was more on materials synthesis than on catalytic reactions or reaction mechanisms. These novel structured gold catalysts will certainly bring new opportunities for studying their performance in various catalytic reactions, the nature of active sites, reaction mechanisms, and correlations between structure and catalytic properties.