Investigation On Platinum Nanowire Electrode Of Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cell(PEMFC) is a clean generation device, and has advantages of high effiency, high power density, quick start and no pollution. It is vey promising in electronic viecles and portable power, and is very important in the future energy system. Membrane electrode assembly(MEA) is the core component in PEMFC, and the oxygen reduction reaction(ORR) in cathode is the limiting step of the whole electrochemical reaction in MEA. Therefore, improving the cathode performance is critical.In this paper, Pt nanowire electrodes with gradient Pt are novelly prepared by decal transfer method. Additionally, a method for accelerating the electrode preparation and improving Pt utilization is developed by using the Pt nanoparticles as growth seeds. The cathode performance and micro-morphology are analysed by single cell testing and physical characterizations.The cathodes have two kinds of matrix: the carbon matrix and mixture matrix. In the case of carbon matrix, the effect of Pt loading, carbon loading and Nafion ionomer content both in and on the catalyst layer are investigated. It is proved that these components will affect the Pt nanowire distribution and proton or gas transfer. The optimal performance of the cathode is achieved at 0.30 mgPt cm-2, 0.10 mgC cm-2, 10 wt% ionomer in the matrix and 0.10 mg cm-2 ionomer on the catalyst layer. The current density at 0.60 V is 1.4 A cm-2, and peak power density is 0.93 W cm-2, which is about 7% higher than that of the commercial GDE electrode with 0.40 mgPt cm-2.In the case of mixture matrix, which is made of mixing the carbon powder and very little Pt/C, the effect of Pt nanoparticle and carbon loading in the matrix are investigated. The Pt nanoparticle seeds provide low energy interfaces for Pt nucleation and thus induce the Pt nanowire growth, finally reducing the Pt aggregation. However, excessive Pt seeds will decrease the Pt nanowire crystallinity, and results in deteriorated catalytic activity. The optimal Pt nanoparticle and carbon loading are 0.025 mg cm-2 and 0.10 mg cm-2, respectively. The total Pt loading is just 0.225 mg cm-2, and the cathode performance is similar with the commercial GDE electrode.In conclusion, this work develops a novel and important technical route for MEA research and production.