ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING, vol.48, no.12, pp.15895-15902, 2023 (SCI-Expanded)
Use of carbon-supported bimetallic catalysts is a promising approach for reducing the cost of platinum needed for the electrocatalysis of the oxygen reduction reaction at the cathode of PEM fuel cells. Structural properties and composition of bimetallic nanoparticles can greatly affect the catalytic activity. This work presents the results obtained by carbon-supported PtAg catalysts prepared in different ratios using two different techniques for dispersing the catalyst ink; mechanical stirring and ultrasonication. Characterization of catalysts was carried out by X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray analysis and cyclic voltammetry. The average crystal sizes varied between 2.4 and 6.6 nm and were significantly smaller in catalysts prepared by ultrasonication. Composition also affected the particle size: smaller particles were obtained from equal compositions of Pt and Ag, while high Ag contents led to significant agglomeration. The highest electroactive surface area was obtained from PtAg/C-61u with 518 cm(2)/mgPt. Catalysts prepared by ultrasound had relatively higher electroactive surface areas, and even exhibited slightly higher mass activities compared to the commercial Pt/C. Overall, PtAg catalysts were found to be promising in terms of reducing the platinum load at the cathode.