Zeolite Proton Conducting Membrane for Micro Fuel Cell Applications

Abstract

Supported and self-supporting ZSM-5 membranes (Si/Al = 25) were prepared, assembled and tested for hydrogen fuel cell performance. A Grotthus-like mechanism is proposed for the proton conduction in hydrated zeolites, where the protons hop between neighbouring aluminium sites along a water bridge in the zeolite pores. The supported ZSM-5 membrane was prepared by seeding and secondary regrowth method on cellulose paper, whereas the self-supporting zeolite membrane consists of an array of micromembranes on silicon substrate. The self-supporting HZSM-5 membrane had an open-circuit voltage (OCV) of 0.77 V compared to 0.90 V for supported HZSM-5 and 0.98 V for Nafion 117. The differences are attributed to the contact between the electrode, catalyst and membrane layers in the assembly. The selfsupporting HZSM-5 yielded a maximum power density (MPD) of 19.4 mW cm -2 compared to 14.4 mW cm -2 for supported HZSM-5 and 35 mW cm -2 for Nafion 117.

Prototropic Exchange Governs T1 and T2 Relaxivities of a Potential MRI Contrast Agent Nanozeolite Gd−LTL with a High pH Responsiveness

“…Probably, a reaction path of very fast hops of water protons from the first coordination sphere of the Gd 3+ -ion across clusters of hydronium ions (connected by hydrogen bonds) to the bulk water outside the zeolite is dominating the propagation of the relaxivity to the bulk water outside the zeolite (see Figure ). Such a proton hopping mechanism, also known as the Grotthuss mechanism, has been put forward as an explanation for the exceptionally high water proton mobility in zeolites, − and a similar mechanism has been proposed for the high methanol proton mobility in zeolite ZSM-5 . The protonated clusters may be associated with the Brønsted acidic silanol groups, framework oxygen atoms, and Gd 3+ -bound water molecules.…”

Recent advances on Zeolite modification for direct alcohol fuel cells (DAFCs)

“…used a Nafion-TiO2 composite membrane to obtain six times higher current density 67 , while Han, et.al. 68 studied the zeolite composite membrane which more stable at high temperature that indirectly affects the permeability.…”

“…The zeolite itself has a similarity to other PEM materials which makes it suitable for a DAFC. The zeolite membrane may appear in the form of pure zeolite itself, 68 as a composite with mentioned materials 73,75,76,[81][82][83] or as a composite form with other new materials. 84 Compared to the existing membrane materials, the zeolite composite membranes give improved performance in term of proton conductivity and alcohol crossover.…”

“…68,76,82 Incorporation of zeolite into existing membranes will block the pores in membrane matrices 81 thus increases the diffusion resistance and reduce the alcohol crossover. The alcohol crossover in a zeolite composite membrane is also affected by the hydrophobicity of zeolites.…”

Proton conducting zeolite films for low-voltage oxide-based electric-double-layer thin-film transistors and logic gates

“…[1][2][3][4][5][6][7] Lately, increasing attention has been focused on proton conductivity property in 3D nanoporous zeolite lms, as well as the application of zeolite lms in proton exchange membrane fuel cells (PEMFCs). [8][9][10] Among tens of developed zeolite lms, zeolite lms with Linde Type A (LTA) structure, with a uniform pore size of about 0.4 nm, are of special interest, and show excellent performance in hydrophilic separations. 11,12 Recently, we have developed a seeding-free synthesis strategy for the preparation of high-quality zeolite LTA molecular sieve lms for gas separation by using 3-aminopropyltriethoxysilane (APTES) as a covalent linker.…”