Abstract:

We prepared a Pt/C catalyst for use in proton exchange membrane fuel cells (PEMFCs) by pulse-microwave assisted chemical reduction synthesis. The microstructure and morphology of the as-prepared catalyst was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The catalyst's electrocatalytic performance in the oxygen reduction reaction (ORR) was measured by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and constant potential polarization. The results indicate that pulse-microwave assisted chemical reduction synthesis is an efficient method to prepare PEMFC catalysts and that the pH and the microwave power largely influence the size and dispersion of Pt nanoparticles. At pH 10 and at a microwave power of 2 kW, the Pt nanoparticles were found to be uniform in size and the Pt nanoparticles size ranged between 1.3 and 2.4 nm with an average size of 1.8 nm. Additionally, the Pt nanoparticles were found to be highly dispersed on the surface of the carbon support. The electrochemical measurements showed that the electrochemical surface area (ESA) of the catalyst was 55.6 m²·g^-1 and the catalyst exhibited superior performance and stability in the ORR. The maximum power density of the single cell was 2.26 W·cm^-2·mg^-1 for the catalyst prepared at a microwave power of 2 kW and a pH of 10 as the cathode material. The maximum power density was higher than that of the catalyst prepared using a microwave power of 1 kW (2.15 W·cm^-2·mg^-1) and also higher than that of the catalyst from Johnson Matthey (1.89 W·cm^-2·mg^-1).

Key words: Pulse-microwave assisted chemical reduction, Microwave power, pH value, Fuel cell, Pt/C catalyst, Oxygen reduction reaction