Concentration-dependent Morphology Control of Pt-coated-Ag Nanowires and Effects of Bimetallic Interfaces on Catalytic Activity

摘要

Silver nanowires(NWs) coated with platinum(Pt) nanoparticles were synthesized via a galvanic partial replacement of Ag NWs in an aqueous K_2PtCl_6 solution at room temperature. The products were characterized using a combination of electron microscopies,selected area electron diffraction,energydispersive X-ray mapping and X-ray diffraction. The surface morphology and Pt/Ag composition ratios are controlled by adjusting the K_2PtCl_6 concentration. Different concentrations result in various surface morphologies including rough nanoparticle coating,porous and relatively smooth surfaces. The formation mechanism was discussed based on the lattice constants' difference,concentration driven nucleation,consumption of Ag NWs,and stoichiometry of the replacement reaction. The effects of the bimetallic interface on the catalytic activity toward the reduction of 4-nitrophenol by sodium borohydride were studied. The activity of Ag–Pt NWs is highly enhanced over monometallic nanostructures,and optimized by a low Pt loading of 1.34 at.%,which indicates a catalytic role of the inter-metallic interface for the electron transfer.