Pulse reverse electrodeposition of Pt–Co alloys onto carbon cloth electrodes

Abstract

Galvanostatic pulse reverse (PR) electrodeposition of Pt–Co alloys onto pretreated carbon cloth from sulfate solutions has been conducted. The aim is to utilize the anodic current applied during the reverse time to manipulate the morphology and composition of the Pt–Co alloys through a dealloying process. The cathodic current density was found to have a strong effect on the amount and the morphology of the deposited Pt–Co, but not on its composition, over the tested range (20–200mAcm−2). A higher current density enhances the Pt–Co nucleation process leading to smaller and finer grained Pt–Co alloy electrodeposits, and ultimately to a higher electroactive surface area. Applying the anodic current over a current density range of 50–200mAcm−2 does not substantially alter the amount, morphology or composition of the deposited Pt–Co alloys, with the Pt contents remaining between 91 and 94mol%. For the PR electrodeposition under the conditions studied, regardless of the magnitude applied, the anodic current does not indicate any dissolution of the Pt–Co alloy deposits, which is supported by the anodic dissolution experiment. Thus, the morphology and composition of the Pt–Co alloy deposits produced by PR electrodeposition are not significantly different from those produced by pulse current electrodeposition at the same cathodic current density.