An inorganic–organic proton exchange membrane for fuel cells with a controlled nanoscale pore structure

Abstract

Proton exchange membrane fuel cells have the potential for applications in energy conversion and energy storage, but their development has been impeded by problems with the membrane electrode assembly. Here, we demonstrate that a silicon-based inorganic-organic membrane offers a number of advantages over Nafion--the membrane widely used as a proton exchange membrane in hydrogen fuel cells--including higher proton conductivity, a lack of volumetric size change, and membrane electrode assembly construction capabilities. Key to achieving these advantages is fabricating a silicon membrane with pores with diameters of approximately 5-7 nm, adding a self-assembled molecular monolayer on the pore surface, and then capping the pores with a layer of porous silica. The silica layer reduces the diameter of the pores and ensures their hydration, resulting in a proton conductivity that is two to three orders of magnitude higher than that of Nafion at low humidity. A membrane electrode assembly constructed with this proton exchange membrane delivered an order of magnitude higher power density than that achieved previously with a dry hydrogen feed and an air-breathing cathode.

Replication of flexible polymer membranes with geometry-controllable nano-apertures via a hierarchical mould-based dewetting

“…F ree-standing nano-membranes have been fabricated from various materials, such as Si-based inorganics [1][2][3][4][5][6] , thin metal foils 7,8 and other types of nano-materials [9][10][11][12][13][14] , for use in a wide range of applications including shadow masking 3,4 , molecular separation 5,6,15 , plasmonics 4,7 , energy devices [16][17][18] and bio-inspired microfluidic devices 19,20 . In general, a series of standard semiconductor processes and/or specific materials 7,21 with high mechanical rigidity have been required to maintain the membrane's shape firmly without mechanical fracture or tear against external forces that arise during the handling process.…”

Ion transport controlled by nanoparticle-functionalized membranes

“…Perhaps most importantly, we have demonstrated a desirable and readily attainable feature of specifically tailoring transport through a suitable choice of encapsulating ligand chemically absorbed to the NP surface. In this regard, we are able to achieve a desired functionality in a manner similar to, but distinctly different from, those using self-assembled monolayers (SAMs) [35][36][37][38][39][40][41] , b a (1), under the assumption of a fixed membrane charge density, |X|. Deviations to the model are most prevalent at low electrolyte concentration, resulting from the fact that |X| is not a constant, but depends on the electrolyte concentration as shown in the inset.…”

“…NATURE COMMUNICATIONS | DOI: 10.1038/ncomms6847 ARTICLE which have received considerable attention for a wide variety of applications, including fuel cells 37 and biosensors 42 . In approaches based on SAMs, chemical interactions are engineered into pre-existing porous substrates by utilizing a favourable surface chemistry to bind a monolayer of functionalized molecules.…”

Introducing catalyst in alkaline membrane for improved performance direct borohydride fuel cells

“…The ever-increasing demand on powering portable devices has generated a worldwide effort towards the development of high-energydensity power sources [1]. Polymer electrolyte membrane fuel cells (PEMFCs) have attracted increasing interest as promising power sources for portable and transportation applications because of their high energy densities, low operating temperatures and ease of transportation and storage [2][3][4].…”

“…Currently used electrolyte membrane was mainly fluoropolymer based materials such as Nafion, developed by DuPont. Although the Teflon-like molecular backbones give those materials excellent longterm stability in both oxidative and reductive environments, the fuel cells using Nafion membrane suffered from using expensive precious cathode catalyst and some technological problems [1,3,5].…”