Galvanic replacement synthesis of Ag_xAu_1−x@CeO₂ (0 ≤ x ≤ 1) core@shell nanospheres with greatly enhanced catalytic performance

A galvanic replacement strategy has been successfully adopted to design Ag_xAu_1−x@CeO₂ core@shell nanospheres derived from Ag@CeO₂ ones. After etching using HAuCl₄, the Ag core was in situ replaced with Ag_xAu_1−x alloy nanoframes, and void spaces were left under the CeO₂ shell. Among the as-prepared Ag_xAu_1−x@CeO₂ catalysts, Ag_0.64Au_0.36@CeO₂ shows the optimal catalytic performance, whose catalytic efficiency reaches even 2.5 times higher than our previously reported Pt@CeO₂ nanospheres in the catalytic reduction of 4-nitrophenol (4-NP) by ammonia borane (AB). Besides, Ag_0.64Au_0.36@CeO₂ also exhibits a much lower 100% conversion temperature of 120 °C for catalytic CO oxidation compared with the other samples.