Ultrathin platinum-group metal coated hierarchical flowerlike gold microstructure: Electrochemical design and characterization

The deliberate tailoring of hierarchical flowerlike gold microstructure (HFGMs) at the ultrathin level is an ongoing challenge and could introduce opportunities for new fabrication and application in many fields. In this paper, a templateless, surfactantless, electrochemical strategy for fabrication of ultrathin platinum-group metal coated HFGMs is proposed. HFGMs were prepared by simple electrodeposition on an indium tin oxide (ITO) substrate. The resulting HFGMs enables the deposition of an ultrathin overlayer through copper underpotential deposition (UPD), followed by spontaneous replacement of the copper with the platinum-group metal to yielded a uniform and ultrathin Pt-group metal layer on the HFGMs surface. Thus prepared bimetallic “core-shell” sample has been characterized by cyclic voltammetry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray maps and X-ray diffraction (XRD). This is a very general and powerful technique for the fabrication of hierarchical, ultrathin coating, bimetallic “core-shell” microstructure, which, in turn, opens up the possibility of building more complex multicomponent hierarchical microstructure with potential application, such as electrocatalysis, biosensors and nanodevices, etc.