Ultrasound-assisted synthesis of Pt–Co/C bimetallic alloys for oxygen reduction in PEM fuel cells

Abstract

Carbon-supported Pt–Co (Pt–Co/C) nanoparticles of varying composition were synthesized using a sonochemical technique in the presence of PVP as a stabilizing agent. X-ray diffraction (XRD) analysis revealed that all compositions of as-synthesized Pt–Co/C nanoparticles exhibited a face centered cubic (fcc) structure. Transmission electron microscopy (TEM) images showed the narrow size distribution and the uniform dispersion of Pt and Co on the carbon support. The electrochemical properties of Pt–Co/C electrocatalysts were analysed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The electrochemical properties of the Pt₈₃–Co₁₇/C composition exhibited the best catalytic activity and the highest stability for the oxygen reduction reaction (ORR) among all compositions synthesized in this study. The ORR performance is reported in terms of the electrochemically active surface area (EASA) and current density. The current density decreased with an increase in Co content and followed the trend of Pt₈₃–Co₁₇/C > Pt₇₅–Co₂₅/C > Pt₅₀–Co₅₀/C. The fabricated PEM fuel cell (PEMFC) presented a power of 0.176 W cm⁻² at 0.436 V using the Pt₈₃–Co₁₇/C cathode and the 40% Pt/C anode and followed the same trend as the current density.