Investigating the Hybrid-Structure-Effect of CeO2-Encapsulated Au Nanostructures on the Transfer Coupling of Nitrobenzene

Abstract

Due to the obvious distinctions in structure, core–shell nanostructures (CSNs) and yolk–shell nanostructures (YSNs) exhibit different catalytic behavior for specific organic reactions. In this work, two unique autoredox routes are developed to the fabrication of CeO₂-encapsulated Au nanocatalysts. Route A is the synthesis of well-defined CSNs by a one-step redox reaction. The process involves an interesting phenomenon in which Ce³⁺ can act as a weak acid to inhibit the hydrolysis of Ce⁴⁺ under the condition of OH⁻ shortage. Route B is the fabrication of monodispersed YSNs by a two-step redox reaction with amorphous Co₃O₄ as an in situ template. Furthermore, the transfer coupling of nitrobenzene is chosen as a probe reaction to investigate their catalytic difference. The CSNs can gradually achieve the conversion of nitrobenzene into azoxybenzene, while the YSNs can rapidly convert nitrobenzene into azobenzene. The different catalytic results are mainly attributed to their structural distinctions.

Two unique autoredox reaction routes are developed to inhibit the excess hydrolysis of Ce⁴⁺ for the synthesis of well-defined Au@CeO₂ core–shell and yolk–shell nanostructures. Furthermore, the two samples exhibit different catalytic results in the catalytic coupling of nitrobenzene due to their different structures.

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