Electrochemical cycling durability of platinum overlayers formed by self-terminating electrodeposition.

Platinum thin films comprising nominally 1 to 20 atomic overlayers were formed on a gold-coated substrate using the self-terminating electrodeposition (STED) method. The platinum overlayer loading and morphology were characterized using X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), Cyclic Voltammetry (CV) and Chronoamperometry (CA). The durability of these platinum overlayer samples was estimated by subjecting the samples to ex-situ electrochemical potential cycling. The extent of platinum overlayer growth is lower than expected till four STED cycles and then increases non-linearly, leading to increased roughness. The shifts of platinum redox peaks in CVs and Pt4f signals in XPS spectra indicate surface-alloying of gold and platinum. After the durability test, the morphological evolution of platinum overlayers conforms with the extent of platinum dissolution estimated from CVs. Our results reveal that more than four STED cycles are needed to form platinum overlayers that meet the US Department of Energy (DOE) criteria for durability. [Display omitted] • Systematic study of the durability of platinum overlayers formed using 1 to 20 Self-Terminating Electrodeposition cycles. • Non-linear growth in thickness of platinum overlayers with increasing number of Self Terminating Electrodeposition cycles. • Electrochemically durable platinum overlayers correspond to complete surface coverage with platinum. • More than four Self-Terminating Electrodeposition cycles are needed to meet the US Department of Energy durability target. [ABSTRACT FROM AUTHOR]