The fabrication of hollow ZrO2 nanoreactors encapsulating Au–Fe2O3 dumbbell nanoparticles for CO oxidation

Abstract

Nanosized Au catalysts suffer from serious sintering problems during synthesis or catalytic reactions at high temperatures. In this work, we integrate dumbbell-shaped Au–Fe₃O₄ heterostructures into hollow ZrO₂ nanocages to make Au–Fe₂O₃@ZrO₂ 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–Fe₃O₄)@SiO₂@ZrO₂ core–shell nanostructure with a Au–Fe₃O₄ dumbbell nanoparticle (DB) core and SiO₂/ZrO₂ double shells, followed by calcination and the selective removal of the inner SiO₂ shell with alkaline solution to obtain Au–Fe₂O₃@ZrO₂ nanoreactors. The retained ZrO₂ hollow (outer) shells protect the Au NPs from aggregation at temperatures up to 900 °C and show excellent long-term stability. Compared to Au@ZrO₂ yolk–shell nanoreactors, Au–Fe₂O₃@ZrO₂ shows improved activity in CO oxidation due to the active Au–Fe₂O₃ interface. This strategy can be extended to other yolk–shell nanoreactors with various nanocomposites and for different catalytic reactions.