Charge transfer accelerates galvanic replacement for PtAgAu nanotubes with enhanced catalytic activity

Galvanic replacement, one of the popular strategies for producing hollow metallic nanostructures, has enjoyed great success in the past. However, it is rarely used with Au nanoparticles as the self-sacrificed templates, even though these nanoparticles can be produced with well-controlled size, shape, and structure. Here, both Ag and Au from the core-shell Au@Ag nanorods are demonstrated to be involved in the galvanic replacement for producing hollow nanostructures. The enhanced oxidation of metallic Au could be attributed to the close contact between Au and Ag and the unique charge compensation from Au to Ag, both of which are indispensable for the etching of Au via galvanic replacement. As a result of this reaction, these bimetallic nanorods experience a structural evolution from nanorattles, to tip-empty nanorods, and eventually to porous nanotubes. The nanotubes exhibit high catalytic activities in the electrooxidation of formic acid. These results not only disclose the underlying mechanism by which metallic Au could be replaced under mild conditions, but also expand the selection of self-sacrificed templates for galvanic replacement, which is an important reaction in many applications.