Electron microscopy study of new composite materials based on electrospun carbon nanofibers

Abstract

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.

New Carbon Nanofiber Composite Materials Containing Lanthanides and Transition Metals Based on Electrospun Polyacrylonitrile for High Temperature Polymer Electrolyte Membrane Fuel Cell Cathodes

“…The parallel graphene layer sets form loops and pores of nanometer size. Structures of that kind, described in some of our previous studies [ 29 ], appear after pyrolysis at high temperature and illustrate the degree of CNF crystallinity. In Figure 2 c, one can observe a typical carbon black onion-like particle with nanoparticles of Gd (or Gd 2 O 3 ) and ZrO 2 .…”

“…However, at current densities >1.2 A cm −2 (where the main source of such performance is mass transfer losses) the performance of Pt/2 cathode is surprisingly higher than that of commercial one. It can be related to higher macroporosity of such type CNF materials (up to 90% of free volume, according to our previous studies [ 29 ]) compared to the performance of the ink sprayed Pt/carbon black electrode. High macroporosity prevents “flooding” of the cathode which usually happens at high current densities due to massive release of water during electrochemical ORR in the fuel cell.…”

“…HRTEM images reveal crystals with (111) planes perpendicular to their growth direction (longer axis of a nanocrystal). The analysis of Fourier diffraction patterns shows that Pt needles have face-centered cubic (fcc) lattice-like bulk platinum crystals [ 29 ]. Isolated atoms (shown by black arrows) are located close to Pt crystal surface with ledge-steps.…”

“…Earlier we have shown [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], that platinized highly macroporous CNF self-supporting mats, which were obtained by the method of electrospinning (ES) from polyacrylonitrile (PAN) polymer solution [ 38 , 39 ] with further stabilization in air, pyrolysis under vacuum [ 40 ], and platination in hexachloroplatinic acid solution, can be successfully used in HT-PEMFC as gas diffusion electrodes (GDEs), both on cathode and anode sides. Thus, polybenzimidazole membrane PBI-OPht was developed in our group for this purpose [ 41 , 42 ].…”

Synthesis and properties of new 2,3,5,6-tetraaminopyridine based polyheteroarylenes

“…По данным импедансной спектроскопии, протонная проводимость плёночных образцов, полученных на базе ПДИП-2 с последующим допированием 50%-й о-фосфорной кислотой, достигает 280 мСм/см при 160 °C, что практически на порядок превышает проводимость исследованного ранее кардового полимера ПБИ-О-ФТ [7][8][9][10], использованного нами в качестве мембраны для топливного элемента [11][12][13][14][15], и другие мировые аналоги [2]. При этом температура, при которой полимер устойчив в присутствии Н 3 РО 4 , на 15-20 °C выше.…”