Pt-Rich Core/Au-Rich Shell Nanoparticle Formation Using Pulsed Laser-Induced Dewetting and Their Electrochemical Characteristics

The formation of Au-Pt bimetallic nanoparticles (NPs)through thepulsed laser-induced dewetting (PLiD) of Au-Pt bilayer thin filmson patterned dimpled Ta substrates was reported. It has been foundthat the total bilayer film thickness plays a determining role inthe size of the NPs, whereas the NP size does not change much withthe different sputtering order and laser fluence. The dimple coverage,characterizing the formation of NP arrays, depends mainly on the comparisonof the NP diameter to the dimple size. Better overall coverages upto >90% were achieved from the NPs produced from PLiD of the twothinnerfilms, i.e., Au(1.5 nm)Pt(1.5 nm) and Pt(1.5 nm)Au(1.6 nm). The energy-dispersiveX-ray (EDX) spectroscopic analysis confirmed the presence of bimetallicAu-Pt NPs after dewetting. The X-ray photoelectron spectroscopic (XPS)measurements and electrochemical characterization using cyclic voltammetryof the produced bimetallic Au-Pt NPs both showed increased Au surfacecontents after PLiD, providing strong evidence for the formation ofPt-rich core/Au-rich shell NPs. The investigation of the electrochemicalproperties revealed stronger Pt-O bonding on the bimetallicAu-Pt NP surfaces. Furthermore, while Au is enriched on the Pt-richcore/Au-rich shell NP surfaces, a significant Pt content, rangingfrom 10% to close to 40%, is still present on the surface of the producedNPs, which could be useful for bifunctional electrocatalytic reactions.