Accelerated Stress Test of Pt/C Nanoparticles in an Interface with an Anion-Exchange Membrane—An Identical-Location Transmission Electron Microscopy Study

Abstract

The durability of a state-of-the-art Pt/C electrocatalyst was assessed by accelerated stress test (AST) procedures conducted in liquid alkaline electrolyte (0.1 M NaOH) and in solid anion exchange polymer electrolyte using a “dry cell”, i.e. in absence of liquid electrolyte. In a liquid environment, the positive and negative vertex potential values have a great influence on the extent and on the magnitude of the degradations: the loss of electrochemical surface area observed for a wide potential range (0.1 < E < 1.23 V vs RHE) is ascribed to detachment of the Pt nanoparticles from their support. The Pt nanoparticles assist the local corrosion of the carbon support material, eventually yielding solid alkali–metal carbonates that mechanically expel them from their support. Such corrosion is linked to the propensity of the Pt nanoparticles to (i) accept carbon surface groups (COad-like species) when their surface is free of oxides (“reduced” metal state, for E < 0.6 V vs RHE) and then to (ii) electro-oxidize...