The fabrication of hollow ZrO nanoreactors encapsulating Au-FeO dumbbell nanoparticles for CO oxidation.

Nanosized Au catalysts suffer from serious sintering problems during synthesis or catalytic reactions at high temperatures. In this work, we integrate dumbbell-shaped Au-FeO heterostructures into hollow ZrO nanocages to make Au-FeO@ZrO yolk-shell nanoreactors with high activity as well as ultra-high sintering resistance for high-temperature CO oxidation. The synthesis starts with the fabrication of a (Au-FeO)@SiO@ZrO core-shell nanostructure with a Au-FeO dumbbell nanoparticle (DB) core and SiO/ZrO double shells, followed by calcination and the selective removal of the inner SiO shell with alkaline solution to obtain Au-FeO@ZrO nanoreactors. The retained ZrO hollow (outer) shells protect the Au NPs from aggregation at temperatures up to 900 °C and show excellent long-term stability. Compared to Au@ZrO yolk-shell nanoreactors, Au-FeO@ZrO shows improved activity in CO oxidation due to the active Au-FeO interface. This strategy can be extended to other yolk-shell nanoreactors with various nanocomposites and for different catalytic reactions.