Importance of real Fuel Cell Testing vs Rotating Disk Electrode Technique in development of laser-generated PtxNiy electrocatalysts
Yao Li, Universität Duisburg-Essen, Duisburg, Deutschland
Proton exchange membrane fuel cells (PEMFCs) are one of the best candidates for zero-emission engines[1]. In order to overcome the kinetic limitations on the oxygen reduction reaction (ORR), which takes place on the cathode of PEMFCs, a substantial amount of research effort has been directed toward the development of Pt-based catalysts that exhibit higher intrinsic activity and durability than conventional polycrystalline Pt nanoparticles (NPs) [2,3]. Furthermore, the novel catalysts are favorable for the reduction of the Pt amount (Platinum-loading) in current PEMFC stacks to meet the cost requirements for large-scale automotive applications [4]. In this work, we have successfully generated stable ligand-free PtxNiy colloids by pulsed laser ablation in water, which were subsequently deposited on carbon particles (Vulcan XC72R) to obtain electrocatalysts for the ORR. Then, the laser-generated catalysts were tested ex situ via the rotating disk electrode (RDE) technique and in situ in a PEMFC. From a more practical and industrial point of view, the goal of this study is to compare the ORR activity and durability of the synthesized catalysts in RDE- and real fuel cell-tests, pointing out the sources for differences observed in the general performance when using RDE or PEMFC. It was found that the activity of the Ni-rich catalysts was significantly improved and even higher than that of the pure Pt after the durability test on the RDE, while they exhibited lower performances compared to other catalysts in the PEMFC. In addition, although a big difference of the durability in the RDE- and fuel cell-tests was presented by the Ni-rich catalysts, the stabilities of other catalysts demonstrated the same trend in both tests. The findings of this work provide impetus to overcome the challenges in translating the performance from the RDE to real fuel cells due to their different testing standards and conditions. [1] A. Heinzel, F. Mahlendorf, J. Roes, Brennstoffzellen: Entwicklung, Technologie, Anwendung 2006, C.F. Müller Verlag Huethig GmbH Co KG, Heidelberg, 3. Auflage. [2] V.R. Stamenkovic et al., Science 2007, 315, 493-497. [3] I.E.L. Stephens et al., J Am Chem Soc 2011, 133, 5485-5491. [4] H. A. Gasteiger, S. Kocha, B. Sompalli, F. T. Wagner, Appl. Catal. B 2005, 56, 9-35