Received 6 April 2016 Received in revised form 1 July 2016 Accepted 7 July 2016 Keywords: ORR Polyoxometalates PEM fuel cells Stress test Catalysis 1. Introduction PEMFC are low temperature energy conversion devices, and for this reason they are the most promising candidates as clean and efficient power sources for portable, stationary and electric vehicle applications [1e3]. They commonly utilize noble metals, supported by carbon layered on gas diffusion electrodes (GDE), in order to catalyze hydrogen oxidation and oxygen reduction reactions (HOR and ORR), and Perfluorosulfonate proton exchange membranes to provide proton conduction through the membrane electrode as- sembly (MEA). The expensive catalyst and membrane contribute to * Corresponding author. E-mail address: email@example.com (M. Renzi). http://dx.doi.org/10.1016/j.jpowsour.2016.07.024 0378-7753/© 2016 Elsevier B.V. All rights reserved. The catalytic activity of commercial Pt nanoparticles mixed with mesoporous polyoxometalate Cs3H2PMo10V2O40 towards oxygen reduction reaction is evaluated. The polyoxometalate co-catalyst is prepared by titration of an aqueous solution of phosphovanadomolibdic acid. SEM micrography shows reduction particle size to less than 300 nm, while XRD confirms that the resulting salt maintains the Kegging structure. The composite catalyst is prepared by mixing the POM salt with Pt/C by sonication. RRDE studies show better kinetics for ORR with low Pt loading at the electrode surface. A MEA is assembled by using a Pt/POM-based cathode, in order to assess performance in a working fuel cell. Current vs. potential curves reveals comparable or better performances at 100%, 62% and 17% relative humidity for the POM-modified MEA with respect to a commercial MEA with higher Pt loading at the cathode. Electrochemical impedance spectroscopy (EIS) confirms better kinetics at low relative humidity. Finally, an accelerated stress test (AST) with square wave (SW) between 0.4 V and 0.8 V is performed to evaluate MEA stability for at least 100 h and make predictions about lifetime, showing that after initial losses the catalytic system can retain stable performance and good morphological stability.
|Titolo:||Low platinum loading cathode modified with Cs3H2PMo10V2O40 for polymer electrolyte membrane fuel cells|
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||Articolo|