Comprehensive Studies on the Effect of Reducing Agents on Electrocatalytic Activity and Durability of Platinum Supported on Carbon Support for Oxygen Reduction Reaction

Abstract

Abstract Platinum supported on carbon support (Pt/C) is currently the most common and practicable electrocatalyst for the real application of polymer electrolyte membrane fuel cells (PEMFCs). In this work, it was found that the nature of a reducing agent has noteworthy influence on Pt nanoparticles growth and distribution over acid-treated-Vulcan carbon support (Pt/AT-VC), which was employed to catalyze the oxygen reduction reaction (ORR) for PEMFC. Three distinct reducing agents, i.e., sodium borohydride (BH), sodium citrate (CA), and formaldehyde (FMY), were employed for Pt/AT-VC preparation through the impregnation-reduction approach. The impacts of the reducing agent on Pt nanoparticles size and its distribution over carbon support were scrutinized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) techniques. The electrocatalytic performance for ORR was subsequently studied by a three-electrode setup with rotating ring-disc electrode (RRDE) characterization and practical fuel cell operation. The ORR kinetics and mechanism were confirmed from RRDE, and it was well correlated with the durability test and single-cell results. Based on the results, the catalysts’ performances for practical PEMFC can be arranged in the order of Pt/AT-VC (BH) < Pt/AT-VC (CA) < Pt/AT-VC (FMY), implying the significance of selecting the reducing agent for the preparation of Pt/C for PEMFC real application.