Effect of Cerium Oxide Nanoparticle Morphology on the Performance and Durability of Hydrogen/Air Fuel Cell Electrodes

Abstract

There has been considerable research on ceria (CeO2) in catalytic applications due to its excellent redox property, providing the ability to easily shift Ce4+ to Ce3+ [1]. This leads to a change in oxidation states and the number of oxygen vacancy defects by minimal activation energy. The catalytic property of CeO2 is directly related to its oxygen storage capacity (OSC) which stands for the quantity of oxygen vacancies that a crystal structure is capable to host. In our previous study, utilization of CeO2 as an additive provided excellent oxygen storage capacity and enhancement in the performance and durability for the cathode of the PEM fuel cell [2]. In the present study, CeO2-based additives with different morphologies including cubic (c-CeO2), rod (r-CeO2), and octahedral (o-CeO2) incorporated into the cathode and their impact on the ORR, performance, and durability of the electrode for hydrogen/air fuel cell was explored. As the first step, CeO2 additives were successfully synthesized via a hydrothermal method and characterized physical techniques such as BET, XRD, and SEM. In the prepared electrodes, the Pt/C and Nafion® loadings were kept constant while varying the CeO2/(Pt/C) loadings. The results have shown an overall enhancement in fuel cell performance (up to 31.8% increase in maximum power density) for cubic-CeO2 loadings reaching only 0.075 mg.cm-2 (20% CeO2). In addition, a fixed additive amount (20%) was employed for different morphologies as well. It was determined that all morphologies exhibited an enhancement in the overall performance compared to Pt/C-based electrode.