Proton Transport in Electrospun Hybrid Organic–Inorganic Membranes: An Illuminating Paradox

Abstract

International audienceChemistry and processing have to be judiciously combined to structure the membranes at various length scales to achieve efficient properties for polymer electrolyte membrane fuel cell to make it competitive for transport. Characterizing the proton transport at various length and space scales and understanding the interplays between the nanostructuration, the confinement effect, the interactions, and connectivity are consequently needed. The goal here is to study the proton transport in multiscale, electrospun hybrid membranes (EHMs) at length scales ranging from molecular to macroscopic by using complementary techniques, i.e., electrochemical impedance spectroscopy, pulsed field gradient-NMR spectroscopy, and quasielastic neutron scattering. Highly conductive hybrid membranes (EHMs) are produced and their performances are rationalized taken into account the balances existing between local interaction driven mobility and large-scale connectivity effects. It is found that the water diffusion coefficient can be locally decreased (2 x 10(-6) cm(2) s(-1)) due to weak interactions with the silica network, but the macroscopic diffusion coefficient is still high (9.6 x 10(-6) cm(2) s(-1)). These results highlight that EHMs have slow dynamics at the local scale without being detrimental for long-range proton transport. This is possible through the nanostructuration of the membranes, controlled via processing and chemistry

Electrospun nanofibre composite polymer electrolyte fuel cell and electrolysis membranes

“…To date, only the second of the above routes has been explored to some extent in association with an electrospinning deposition step, where the cross-linked mat was the reinforcing or the ion conducting material. In particular, the polymer solution was mixed with a cross-linker molecule followed by electrospinning into a nanofibre mat and subsequent thermal treatment to induce the reaction [120,137,138] or the polymer solution was electrospun into a nanofibre mat exposed to a cross-linker either in vapour or liquid form under required conditions [65,[140][141][142][143]. The latter of the above approaches was employed to prepare composite membranes of PFSA and polyvinylalcohol for DMFC and PEMFC applications.…”

Electrospun Hybrid Perfluorosulfonic Acid/Sulfonated Silica Composite Membranes

“…Unfortunately, membrane conductivity decreased over time as the sPOSS particles slowly leached out of the membrane. More recently, Laberty-Robert et al [ 29 , 30 , 31 ] described the fabrication of organic/inorganic membranes composed of a functionalized silica network with sulfonic acid groups, embedded in a hydrophobic polymer—poly(vinylidene fluoride-co-hexafluoropropylene). Membranes were prepared by combining in-situ sol-gel chemistry and electrospinning.…”

One-step nonhydrolytic sol–gel synthesis of mesoporous TiO2 phosphonate hybrid materials

“…The development of porous hybrid organic–inorganic materials has been a major goal for materials scientists for more than 25 years [1–3]. Combining inorganic and organic moieties at the nanoscale allows the design of tailor-made functional materials with enhanced or new properties, adapted to a wide range of advanced applications [4–7]. In Class I hybrid materials, the inorganic and organic parts are linked through weak bonds (e.g., van der Waals or hydrogen bonds), while in Class II hybrid materials, they are linked by stronger ionocovalent or covalent bonds [8].…”