In this work, we introduce the application of gas diffusion electrodes (GDE) for benchmarking the electrocatalytic performance of high surface area fuel cell catalysts. It is demonstrated that GDEs offer several inherent advantages over the state-of-the-art technique, i.e. thin film rotating disk electrode (TF-RDE) measurements for fast fuel cell catalyst evaluation. The most critical advantage is reactant mass transport. While in RDE measurements the reactant mass transport is severely limited by the gas solubility of the reactant in the electrolyte, GDEs enable reactant transport rates similar to technical fuel cell devices. Hence, in contrast to TF-RDE measurements, performance data obtained from GDE measurements can be directly compared to membrane electrode assembly (MEA) tests. Therefore, the application of GDEs for the testing of fuel cell catalysts closes the gap between catalyst research in academia and real applications.

A nano-scale understanding of the degradation mechanisms responsible for the performance loss of high surface area (HSA) catalysts implemented in polymer electrolyte membrane fuel cells (PEMFC) is essential for the development of improved catalysts. Here we present a systematic study of the degradation mechanisms of a HSA carbon supported Pt (Pt/C) catalyst. By monitoring the electrochemical surface area (ECSA) loss under accelerated stress test (AST) protocols with identical location transmission electron microscopy (IL-TEM), it is shown that different degradation mechanisms are responsible of the performance loss of Pt/C depending on the applied AST protocol. Three different AST protocols have been applied, i.e. i) load cycles between 0.6–1.0 V_RHE, ii) start/stop cycles between 1.0–1.5 V_RHE, and iii) a treatment consisting of a mix of both conditions (cycling between 0.4–1.4 V_RHE). During load cycles the main degradation mechanisms are nanoparticle (NP) migration as well as Pt dissolution and re-deposition. However, after applying start/stop cycles only NP detachment from the carbon support is detect, whereas the third AST protocol induces all degradation modes concomitantly.

Cost and lifetime currently hinder widespread commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Reduced electrode Pt loadings lower costs; however, the impact of metal loading (on the support) and its relation to degradation (lifetime) remain unclear. The limited research on these parameters stems from synthetic difficulties and lack of in situ analytics. This study addresses these challenges by synthesizing 2D and 3D Pt/C model catalyst systems via two precise routes and systematically varying the loading. Pt dissolution was monitored using on-line inductively coupled plasma mass spectrometry (on-line-ICP-MS), while X-ray spectroscopy techniques were applied to establish the oxidation states of Pt in correlation with metal loading. Dissolution trends emerge which can be explained by three particle proximity dependent mechanisms: (1) shifts in the Nernst dissolution potential, (2) redeposition, and (3) alteration of Pt oxidation states. These results identify engineering limitations, which should be considered by researchers in fuel cell development and related fields.