A general one-pot strategy for the synthesis of Au@multi-oxide yolk@shell nanospheres with enhanced catalytic performance

By integrating redox self-assembly and redox etching processes, we report a general one-pot strategy for the synthesis of Au@multi-M(x)O(y) (M = Co, Ce, Fe, and Sn) yolk@shell nanospheres. Without any additional protecting molecule or reductant, the whole reaction is a clean redox process that happens among the inorganic metal salts in an alkaline aqueous solution. By using this method, Au@Co(3)O(4)/CeO(2) (Au@Co–Ce), Au@Co(3)O(4)/Fe(2)O(3) (Au@Co–Fe), and Au@CeO(2)/SnO(2) (Au@Ce–Sn) yolk@shell nanospheres with binary oxides as shells, Au@Co(3)O(4)/CeO(2)/Fe(2)O(3) (Au@Co–Ce–Fe) yolk@shell nanospheres with ternary oxides as shells and Au@Co(3)O(4)/CeO(2)/Fe(2)O(3)/SnO(2) (Au@Co–Ce–Fe–Sn) yolk@shell nanospheres with quaternary oxides as shells can be obtained. Subsequently, the catalytic CO oxidation was selected as the catalytic model, and the Au@Co–Ce system was chosen as the catalyst. It was found that the catalytic activity of Au@Co–Ce yolk@shell nanospheres can be optimized by altering the relative proportion of Co and Ce oxides.