X-ray Photoelectron Spectroscopic Analysis of Pt Nanoparticles on Highly Oriented Pyrolytic Graphite, Using Symmetric Component Line Shapes

Abstract

The X-ray photoelectron spectroscopic characterizations of Pt nanoparticles evaporated onto untreated and Ar+-treated highly oriented pyrolytic graphite surfaces, with, respectively, low and high surface defect densities have been studied using multicomponent analysis with symmetric line shapes: each Pt4f spectral component (f7/2 and f5/2) was deconvoluted into three symmetric peaks. On analyzing the relationships among the Pt4f, C1s, and O1s spectra, we attribute these peaks to the existence of surface oxidation on the platinum nanoparticles and to the different electronic configurations of surface and bulk Pt atoms. We use the varying intensities of these component peaks, as a function of deposited Pt, to explain the changing shape of the Pt4f asymmetric envelope with nanoparticle size.