To create a new type of catalytic gas diffusion layer for a high-temperature hydrogen/air polymer-electrolyte membrane fuel cell (HT-PEMFC), a new electrospun carbon nanofiber (CNF)-based platinized nanocomposite was formed.

Complex composite carbon nanofiber fuel cell electrode shows advantages compared to non-composite and less durable commercial carbon black ones.

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Crystalline platinum nanoparticles supported on carbon nanofibers were synthesized for use as an electrocatalyst for polymer electrolyte membrane fuel cells. The nanofibers were prepared by a method of electrospinning from polymer solution with subsequent pyrolysis. Pt nanoneedles supported on polyacrylonitrile pyrolyzed electrospun nanofibers were synthesized by chemical reduction of H 2 [PtCl 6 ] in aqueous solution. The synthesized electrocatalysts were investigated using scanning, high resolution transmission and scanning transmission electron microscopies, EDX analysis and electron diffraction. The shape and the size of the electrocatalyst crystal Pt nanoparticles were controled and found to depend on the method of H 2 [PtCl 6 ] reduction type and on conditions of subsequent thermal treatment. Soft Pt reduction by formic acid followed by 100 C thermal treatment produced needle-shape Pt nanoparticles with a needle length up to 25 nm and diameter up to 5 nm. Thermal treatment of these nanoparticles at 500 C resulted in partial sintering of the Pt needles. When formic acid was added after 24 h from the beginning of platinization, Pt reduction resulted in small-size spherical Pt nanoparticle of less than 10 nm in diameter. Reduction of H 2 [PtCl 6 ], preadsorbed on electrospun nanofibers in formic acid with further treatment in H 2 flow at 500 C, resulted in intensive sintering of platinum particles, with formation of conglomerates of 50 nm in size, however, individual particles still retain a size of less than 10 nm.Electrochemically active surface area (ECSA) of Pt/C catalyst was measured by electrochemical hydrogen adsorption/desorption measurements in 0.5 M H 2 SO 4 . ECSA of needle-shape Pt nanoparticles was 25 m 2 g À1 . It increased up to 31 m 2 g À1 after thermal treatment at 500 C, likely, due to amorphous structures removal from carbon nanofibers and retaining of Pt nanoneedle morphology. ECSA of small-size spherical Pt nanoparticles was 26 m 2 g À1 . Further thermal treatment at 500 C in vacuum decreased ECSA down to 20 m 2 g À1 due to Pt sintering and Pt active sites deactivation. The thermal treatment of small-size spherical Pt nanoparticles in H 2 flow at 500 C produced agglomerates of Pt nanoparticles with ECSA of 14 m 2 g À1 .

Different polyheteroarylenes, such as m‐polybenzimidazole, polyphenylene oxide, polymer of intrinsic microporosity (PIM‐1) and poly(N‐phenylene‐benzimidazole) were electrospun to obtain self‐supporting polymer nanofiber mats. The mats after heat treatment, which contains stabilization in air at 250–350 °C and pyrolysis at 900–1000 °C under vacuum, convert into carbon nanofiber paper, a material which is suitable for Pt nanoparticle deposition. The possibility of usage of the obtained carbonized nanocomposites as entire gas diffusion electrodes for high temperature polymer electrolyte membrane fuel cell is shown.

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