Modulating the alloying mode in the doping-induced synthesis of Au-Pd nanowires

Heterogeneous doping is one effective strategy for synthesizing metal alloy nanowires. Herein, the heterogeneous doping processes of Pd on the ultrathin Au nanowires were systematically modulated and investigated. Au-Pd alloy nanowires with various morphologies and lattice structures can be obtained by adjusting the morphology of the precursor Au nanowires and the kinetics of the heterogeneous doping processes. The effects of the rate of Pd reduction and the concentration of the ligand oleylamine (OAm) on the Pd deposition and alloying mode were articulated. Generally, as the Pd deposition rate decreases, the Pd deposition and alloying mode switches from the island-forming Stransky–Krastanov (SK) mode to the epitaxial Frank-van der Merwe (FM) mode, and eventually to an unconventional twisting alloying mode, where the interdiffusion of Pd and Au causes drastic rearrangement of the lattice structure and formation of helical structures. The kinetics-related variation of alloying mode could also be observed in the Au-Ag nanowires, demonstrating a general design principle for the synthesis of alloy nanostructures. In addition, the electrocatalytic performance of various Au-Pd nanowires was evaluated, and the alloy nanowire formed via the SK mode was found to be an excellent electrocatalyst for oxygen reduction and ethanol oxidation.