On the Need of Improved Accelerated Degradation Protocols (ADPs): Examination of Platinum Dissolution and Carbon Corrosion in Half-Cell Tests

E Pizzutilo,J.-P Grote,S Geiger,S Cherevko,K J J Mayrhofer,M Arenz,A Mingers

doi:10.1149/2.0731614jes

Abstract

In this work we employ the advanced scanning flow cell based analytical techniques, viz. inductively coupled plasma mass spectrometry (SFC-ICP-MS) and on-line electrochemical mass-spectrometry (SFC-OLEMS) to directly detect the amounts of dissolved platinum and evolved carbon dioxide in two protocols that are commonly used in the fuel cell community to simulate load cycle and start-stop conditions in proton exchange membrane fuel cells (PEMFCs). In contrast to previous assumptions, claiming a separation between carbon corrosion and platinum dissolution, in both standard protocols platinum dissolution and carbon corrosion are present at low rates, which is also reflected by a comparably low ECSA decrease. On the other hand, a huge increase in rate of both processes is observed during transitions from low to high potential regimes experienced by a PEMFC in operation, here studied in a third protocol covering the whole potential range from 0.6 to 1.5 VRHE. The latter is typically not addressed in literature. This finding is explained by taking into account platinum catalyzed carbon corrosion and transient platinum dissolution. Based on the obtained results, the question is raised on the practical adequacy of the standard protocols for differentiation of degradation processes and simulation of the degradation processes occurring in PEMFCs.

Highlights

On the Need of Improved Accelerated Degradation Protocols (ADPs): Examination of Platinum Dissolution and Carbon Corrosion in Half-Cell Tests
Besides the traditional load cycle and start-stop protocols we investigate a protocol concentrating on potential transitions between 0.6 and 1.5 VRHE, which we call here a “combined cycles” test
One of the most elegant ways to measure the electrochemical surface area (ECSA) with the TF-rotating disk electrode (RDE) is the so-called CO-stripping method, in which the Pt surface area is estimated from the oxidation charge of a CO monolayer

Summary

Introduction

On the Need of Improved Accelerated Degradation Protocols (ADPs): Examination of Platinum Dissolution and Carbon Corrosion in Half-Cell Tests. In 2011 the US Department of Energy (DOE) durability working group and the Fuel Cell Commercialization Conference of Japan (FCCJ) proposed very similar ADPs, in particular, aiming to differentiate between the different degradation mechanisms.[7,8] Based on the literature data available until 2011, it was suggested that relatively low potentials during load cycles and high potentials during start-stop cycles are critical for platinum dissolution and carbon corrosion, respectively.

Results

Conclusion