Au@TiO2 double-shelled octahedral nanocages with improved catalytic properties

Abstract

A novel and facile strategy has been successfully developed to synthesize uniform gold@titanium dioxide octahedral nanocages (Au@TiO₂), which have a well-defined double-shelled structure with Au as the internal shell and TiO₂ as the external shell. The unique Au@TiO₂ double-shelled octahedral nanocages were elaborately fabricated by a Cu₂O-templated strategy combining with spatially confined galvanic replacement. The formation process of these delicate hierarchical octahedral architectures is discussed in detail. The catalytic performance of the Au@TiO₂ double-shelled octahedral nanocages was investigated using the reduction of 4-nitrophenol as a model reaction. The mesoporous structure of both the Au and TiO₂ shells provides direct access for the reactant molecules to diffuse and subsequently interact with the Au shell. This novel catalyst shows excellent and stable activity for the catalytic reduction of 4-nitrophenol, which can be recycled for ten successive cycles of the reaction with a conversion efficiency of more than 90%. The superior catalytic activity attributes to mesoporous double shells, enhanced synergistic effects between the Au and TiO₂ shells and the unique properties of the octahedral structure. More importantly, the as-obtained Au@TiO₂ double-shelled octahedral nanocages also show potential applications in solar cells, organocatalysis and water splitting.