Pt nanowire growth induced by Pt nanoparticles in application of the cathodes for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

Abstract

Improving cathode performance at a lower Pt loading is critical in commercial PEMFC applications. A novel Pt nanowire (Pt-NW) cathode was developed by in-situ growth of Pt nanowires in carbon matrix consisting Pt nanoparticles (Pt-NPs). Characterization of TEM and XRD shows that the pre-existing Pt-NPs from Pt/C affect Pt-NW morphology and crystallinity and Pt profile crossing the matrix thickness. The cathode with Pt-NP loading of 0.005 mgPt-NP cm−2 and total cathode Pt loading of 0.205 mgPt cm−2 has the specific current density of 89.56 A gPt−1 at 0.9 V, which is about 110% higher than that of 42.58 A gPt−1 of the commercial gas diffusion layer (GDE) with Pt loading of 0.40 mg cm−2. When cell voltage is below 0.48 V, the Pt-NW cathode has better performance than the commercial GDE. It is believed that the excellent performance of the Pt-NW cathode is attributed to Pt-NP induction, therefore producing unique Pt-NW structure and efficient Pt utilization. A Pt-NW growth mechanism was proposed that Pt precursor diffuses into the matrix consisting of pre-existent Pt-NPs by concentration driving, and Pt-NPs provide priority sites for platinum depositing at early stage and facilitate Pt-NW growth.