Durability of Electrocatalysts for ORR: Pt on Nanocomposite of Reduced Graphene Oxide with FTO versus Pt/C

Abstract

Catalyst degradation results in performance losses of proton exchange membrane fuel cells (PEMFC) and is caused by electrochemical instability of commonly used platinum on carbon black (Pt/C). In this study, a comparison in durability of commercial Pt/C with a new Pt catalyst on a nanocomposite of fluorine-doped SnO2 (FTO) and reduced graphene oxide (rGO) is carried out. Transmission electron microscopy (TEM) shows similar Pt distributions on support surfaces and Pt particle sizes so that a high comparability of support materials during durability investigation is ensured. High resolution TEM with EDS reveals dispersed Pt anchored at FTO-rGO interfaces. During stripping voltammetry Pt/FTO-rGO provides weaker CO sorption than Pt/C, indicating higher CO tolerances. Accelerated stress testing (0.05-1.47 VRHE) provokes Pt degradation on both supports in comparable rates. However, the FTO-rGO nanocomposite presents the more stable substrate in this study compared to carbon black. Identical location TEM illustrates stable FTO particles in size and position on rGO surface. Moreover, unchanged hydroquinone/quinone (HQ/Q) amounts and double layer capacitance in case of Pt/FTO-rGO were revealed by cyclic voltammetry. On the contrary, standard Pt/C shows significantly more generation of HQ/Q functionalities by a factor of 25 and thus higher carbon corrosion.