Abstract
Novel, hierarchical, flower-like Ag/Cu O and Au/Cu O nanostructures were successfully fabricated and applied as efficient electrocatalysts for the electrochemical reduction of CO . Cu O nanospheres with a uniform size of ~180 nm were initially synthesized. Thereafter, Cu O was used as a sacrificial template to prepare a series of Ag/Cu O composites through galvanic replacement. By varying the Ag/Cu atomic ratio, Ag /Cu O, having a hierarchical, flower-like nanostructure with intersecting Ag nanoflakes encompassing an inner Cu O sphere, was prepared. The as-prepared Ag /Cu O samples presented higher Faradaic efficiencies (FE) for CO and relatively suppressed H evolution than the parent Cu O nanospheres due to the combination of Ag with Cu O in the former. Notably, the highest CO evolution rate was achieved with Ag /Cu O due to the larger electroactive surface area furnished by the hierarchical structure. The same hierarchical flower-like structure was also obtained for the Au /Cu O composite, where the FE (10%) was even higher than that of Ag /Cu O. Importantly, the results reveal that Ag /Cu O and Au /Cu O both exhibit remarkably improved stability relative to Cu O. This study presents a facile method of developing hierarchical metal-oxide composites as efficient and stable electrocatalysts for the electrochemical reduction of CO .
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