Investigation of cathode electrocatalysts composed of electrospun Pt nanowires and Pt/C for proton exchange membrane fuel cells

The present work investigates the effect of cathode electrocatalysts composed of Pt nanowires (Pt-NWs) fabricated by electrospinning method and commercial Pt-loaded carbon black (Pt/C) on the oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell. Pt nanowires are prepared by heating electrospun polyvinyl pyrrolidone (PVP)-Pt composite fibers at high temperatures in air atmosphere. Cathode catalyst layers with different mixing ratios of Pt-NWs and Pt/C are tested to explore their activities toward ORR. The results show that the conventional Pt/C mixed with a small amount of Pt-NWs exhibits better catalytic performance than the pure Pt/C catalysts. Under the same Pt loading of 0.5 mg cm−2, the case of composite electrocatalyst of 0.1 mg cm−2 Pt-NWs and 0.4 mg cm−2 Pt/C presents the best catalytic activities which can be rationalized by enhanced electrochemical surface area and exchange current density in the catalyst layer. The effect of Nafion content is also evaluated and the results show that the optimal content of Nafion ionomer is 30 wt% using such a composite electrocatalyst in cathode catalyst layer.