Electrospun bimetallic PtNi nanowires as electrocatalyst for oxygen reduction reaction in PEMFCs

The present investigation attempts to prepare bimetallic PtNi nanowires by electrospinning method and explore their possible utilization in the cathode catalyst layer for a proton exchange membrane fuel cell as electrocatalysts for oxygen reduction reaction. The influences of manipulation parameters in the electrospinning procedure on the resultant nanowire morphology are examined, including the PVP concentration, the strength of electric field, and the atomic ratio of Pt:Ni. The tests of cyclic voltammetry, linear sweep voltammetry, and accelerated degradation are performed to estimate the electrochemically active surface area (ECSA), oxygen reduction reaction (ORR) activity, and electrochemical performance durability. A membrane electrode assembly (MEA) is further built to test the single cell performance in which the cathode catalyst layer is made of the prepared alloy nanowires. The results reveal that the bimetallic PtNi nanowires can be produced successfully by the electrospinning technique, and the minimum mean diameter of the nanowires could reach 23 nm under the condition of 8 wt% PVP and 1 wt% metal precursors in the polymer solution with applied voltage 14 kV, collection distance 10 cm, and atomic ratio 2:1 of Pt:Ni. Comparing with the conventional Pt/C catalyst, the prepared Pt2Ni1 nanowires present less ECSA but better ORR activity and superior durability in both ECSA and ORR performance. The preliminary test of single cell performance using the Pt2Ni1 nanowires indicates that the electrospun PtNi alloy nanowires are a promising electrocatalyst for ORR, while the optimal structure and compositions in the cathode catalyst layer need to be further resolved.