Pt, Zr, Ni-containing carbon nanofiber composites modified by self-phosphorylating polybenzimidazole as cathode materials for hydrogen-air high-temperature polymer-electrolyte membrane fuel cell

High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) operate at 150–200 °C, making it possible to use hydrogen contaminated with carbon monoxide. However, the main drawback for their distribution is the need to improve stability of membrane-electrode assembly components, especially cathodes. The cathodes based on carbon nanofiber (CNF) mat are free-standing (self-supporting), and are prepared using the method of electrospinning from a polyacrylonitrile solution containing Zr and Ni salts, followed by the stabilization and pyrolysis steps. The composite Zr, Ni-containing Pt/CNF cathodes are obtained after Pt nanoparticle deposition on the CNF surface. A novel self-phosphorylating polybenzimidazole (PBI-6F) was deposited to the surface of Pt/CNF to improve the triple-phase boundary. Substitution of OMe-groups and hydrophobic nature of CF3-groups lead to improvements in proton conductivity and gas transport of the cathode as well as proton-conducting contacts between cathode and membrane. The materials are studied using N2 and CO2 gas adsorption, TEM, HAADF STEM. The operation of the H2/air HT-PEMFC shows that the application of the PBI-6F-covered PBI-6F/Pt/CNF cathode results in an enhancement of HT-PEMFC performance, compared with the uncovered Pt/CNF cathode, providing ~20% increase in maximum power density. The study was financially supported by Russian Science Foundation (grant # 22-13-00065). Elemental analysis was performed with support of Ministry of Science and Higher Education of the Russian Federation using the equipment of Center for Molecular Composition Studies of INEOS RAS. The authors would like to express their gratitude to D. N. Khme lenin and E. N. Cherkovskiy of NRC “KI” for their assistance with electron microscopy data; Yu. A. Volkova, Iv. I. Ponomarev and A. G. Buyanovskaya of INEOS RAS for their contributions to the membrane obtaining, electrospinning results and elemental analysis data; and A. D. Modestov of IPCE RAS for his assistance with electrochemistry data.