The Influence of Applied Potential in the Characteristics of Pt Nanoparticles Electrodeposited on Conductive Substrates

Abstract

Studies about the influence of applied potential on the development of facetted Pt nanocrystallites for the oxygen electroreduction reaction on hydrogen/oxygen PEM fuel cell are presented. High surface area facetted Pt nanoparticles on carbon substrates are obtained by applying a square wave potential pulse of high frequency in aqueous chloroplatinic acid at 25°C. The effect of the lower potential limit of the electrical signal on both the size and crystallograhic orientation of the nanoparticles are evaluated. The net amount of electrodeposited Pt is determined by using a spectrophotometric technique at 402 nm. The characterisation studies of metal electrodeposits revealed the presence of highly facetted Pt nanoparticles having a predominant (111) preferential crystal orientation. The amount of electrodeposited Pt at constant charge decreases with the shift of the lower potential limit of the electrical signal towards more negative potentials due to the increasing contribution for the hydrogen evolution reaction in the global process