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High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) are a very important type of fuel cells since they operate at 150–200 °C, making it possible to use hydrogen contaminated with CO. However, the need to improve the stability and other properties of gas-diffusion electrodes still impedes their distribution. Self-supporting anodes based on carbon nanofibers (CNF) are prepared using the electrospinning method from a polyacrylonitrile solution containing zirconium salt, followed by pyrolysis. After the deposition of Pt nanoparticles on the CNF surface, the composite anodes are obtained. A new self-phosphorylating polybenzimidazole of the 6F family is applied to the Pt/CNF surface to improve the triple-phase boundary, gas transport, and proton conductivity of the anode. This polymer coating ensures a continuous interface between the anode and proton-conducting membrane. The polymer is investigated using CO2 adsorption, TGA, DTA, FTIR, GPC, and gas permeability measurements. The anodes are studied using SEM, HAADF STEM, and CV. The operation of the membrane–electrode assembly in the H2/air HT-PEMFC shows that the application of the new PBI of the 6F family with good gas permeability as a coating for the CNF anodes results in an enhancement of HT-PEMFC performance, reaching 500 mW/cm2 at 1.3 A/cm2 (at 180 °C), compared with the previously studied PBI-O-PhT-P polymer. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile and polyheteroarylenes, such as polybenzimidazole (PBI) and a polymer of intrinsic microporosity (PIM-1), have been employed to prepare nanoporous electrospun carbon nanofiber (CNF)-based materials for high-temperature proton-exchange (or polymer-electrolyte) membrane (HT-PEM) fuel cells. The nanoporous CNF mats are obtained by Nanospider (needle-free) electrospinning method from polymer solution followed by pyrolysis at 1500 °C to form nanoporous electrospun polymer nanofiber self-supporting mats with micropores (D < 2 nm) and mesopores (D 2–50 nm). The nanoporous CNF samples are extensively characterized by N2 and CO2 adsorption applying the BET, BJH, Dubinin–Radushkevich (DR), NLDFT, and GCMC methods, CO2 uptake, Raman spectroscopy, elemental analysis, electrical conductivity, electron microscopy, and XPS. The role of the polymer precursor on the obtained values of specific surface area (SSA) and volume for micro- and mesopores is presented and discussed. The PBI-based CNF material reaches a micropore SSA of 919 m2 g–1 and CO2 uptake of 4.0 mmol g–1 derived from CO2 adsorption (273 K) data, and a micropore SSA of 873 m2 g–1 according to the t-method derived from N2 adsorption data. Close values confirm higher accessibility of micropores compared with the case of PIM-based CNF, where the micropore SSA values derived from CO2 and N2 adsorption data are different and indicate the partial inaccessibility of micropores for low-temperature nitrogen adsorption (77 K). Platinum-decorated CNF mats are successfully tested as electrodes for HT-PEM fuel cells, showing the feasibility of using the mats as cathodes; nevertheless, further optimization is required. For CNF anodes, the HT-PEM fuel cell performance reaches 0.69 V at 0.2 A cm–2 and 0.53 W cm–2 at 1.4 A cm–2 which permits the use of the Pt/CNF mats as anodes. [ABSTRACT FROM AUTHOR]