Persona:
Martín Fernández, Santiago

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Martín Fernández
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Santiago
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2019 - 201912020 - 20212
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Autor: Jensen, Jens Oluf ×

Resultados de la búsqueda

Mostrando 1 - 3 de 3
  • Miniatura
    Publicación
    Polybenzimidazole-Based High-Temperature Polymer Electrolyte Membrane Fuel Cells: New Insights and Recent Progress
    (Springer, 2020) Aili, David; Henkensmeier, Dirk; Martín Fernández, Santiago; Singh, Bhupendra; Hu, Yang; Jensen, Jens Oluf; Cleemann, Lars Nilausen; Li, Qingfeng; https://orcid.org/0000-0002-3510-135X; https://orcid.org/0000-0003-2330-953X; https://orcid.org/0000-0002-0773-5312; https://orcid.org/0000-0001-8644-9615; https://orcid.org/0000-0002-2427-7763; https://orcid.org/0000-0001-5840-7477; https://orcid.org/0000-0002-5460-055X
    High-temperature proton exchange membrane fuel cells based on phosphoric acid-doped polybenzimidazole membranes are a technology characterized by simplified construction and operation along with possible integration with, e.g., methanol reformers. Significant progress has been achieved in terms of key materials, components and systems. This review is devoted to updating new insights into the fundamental understanding and technological deployment of this technology. Polymers are synthetically modified with basic functionalities, and membranes are improved through cross-linking and inorganic–organic hybridization. New insights into phosphoric acid along with its interactions with basic polymers, metal catalysts and carbon-based supports are recapped. Recognition of parasitic acid migration raises acid retention issues at high current densities. Acid loss via evaporation is estimated with respect to the acid inventory of membrane electrode assembly. Acid adsorption on platinum surfaces can be alleviated for platinum alloys and non-precious metal catalysts. Binders have been considered a key to the establishment of the triple-phase boundary, while recent development of binderless electrodes opens new avenues toward low Pt loadings. Often ignored microporous layers and water impacts are also discussed. Of special concern are durability issues including acid loss, platinum sintering and carbon corrosion, the latter being critical during start/stop cycling with mitigation measures proposed. Long-term durability has been demonstrated with a voltage degradation rate of less than 1 μV h−1 under steady-state tests at 160 °C, while challenges remain at higher temperatures, current densities or reactant stoichiometries, particularly during dynamic operation with thermal, load or start/stop cycling.
  • Miniatura
    Publicación
    Self-Standing Nanofiber Electrodes with Pt–Co Derived from Electrospun Zeolitic Imidazolate Framework for High Temperature PEM Fuel Cells
    (Wiley, 2021) Lim, Sung Yul; Martín Fernández, Santiago; Gao, Guohua; Dou, Yibo; Bredmose Simonsen, Søren; Jensen, Jens Oluf; Li, Qingfeng; Norrman, Kion; Jing, Shao; Zhang, Wenjing; https://orcid.org/0000-0002-5011-1951
    Expedited conversion of O2 to H2O with minimal amounts of Pt is essential for wide applicability of PEM fuel cells (PEMFCs). Therefore, it is imperative to develop a process for catalyst management to circumvent unnecessary catalyst loss while improving the Pt utilization, catalytic activity, and durability. Here, the fabrication of a self-standing nanofiber electrode is demonstrated by employing electrospinning. This film-type catalyst simultaneously contains Pt–Co alloy nanoparticles and Co embedded in an N-doped graphitized carbon (Co–Nx) support derived from the electrospun zeolitic imidazolate frameworks. Notably, the flexible electrode is directly transferrable for the membrane-electrode assembly of high temperature PEMFC. In addition, the electrodes exhibit excellent performance, maybe owing to the synergistic interaction between the Pt–Co and Co–Nx as revealed by the computational modeling study. This method simplifies the fabrication and operation of cell device with negligible Pt loss, compared to ink-based conventional catalyst coating methods.
  • Miniatura
    Publicación
    Feasibility of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells based in phosphoric acid-doped membrane
    (ELSEVIER, 2019) Martín Fernández, Santiago; Jensen, Jens Oluf; Li, Qingfeng; García Ybarra, Pedro Luis; Castillo Gimeno, José Luis; https://orcid.org/0000-0002-2427-7763; https://orcid.org/0000-0002-5460-055X
    Factors as the Pt/C ratio of the catalyst, the binder content of the electrode and the catalyst deposition method were studied within the scope of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The Pt/C ratio of the catalyst allowed to tune the thickness of the catalytic layer and so to minimize the detrimental effect of the phosphoric acid flooding. A membrane electrode assembly (MEA) with 0.05 mgPtcm−2 at anode and 0.1 mgPtcm−2 at cathode (0.150 mgPtcm−2 in total) attained a peak power density of 346 mW cm−2. It was proven that including a binder in the catalytic layer of ultra-low Pt loading electrodes lowers its performance. Electrospraying-based MEAs with ultra-low Pt loaded electrodes (0.1 mgPtcm−2) rendered the best (peak power density of 400 mW cm−2) compared to conventional methods (spraying or ultrasonic spraying) but with the penalty of a low catalyst deposition rate.