Graphene Oxide Fuel Cell

Abstract

Graphene oxide (GO) exhibits relatively high proton conduction even at low relative humidity (RH) and temperatures. Thus, multilayered GO film (GO paper) is a promising electrolyte in various cells and batteries. We report the in-plane and through-plane proton conductivities of GO paper at low RH and room temperature. The conductivities were 10 −5 -10 −4 S/cm at RH of 10-20%. We examined the performance of a graphene oxide fuel cell (GOFC) with GO paper as the electrolyte at low RH (<20%) and room temperature. We demonstrated that a simple membrane electrode assembly (MEA) based on Pt/GO/Pt system functioned as a H 2 /O 2 fuel cell. The GOFC with Pt/C electrodes afforded better fuel cell performance than a MEA composed of Pt/C electrodes and Nafion electrolyte. GO paper composed of nano-sized GO (nanoGO) flakes enhanced the performance of the GOFC, particularly the current density. Furthermore, a composite of Fe phthalocyanine (PcFe) /reduced GO (rGO)/TiO 2 could act as the Pt-free oxygen electrode in GOFC, although the fuel cell performance should be improved for practical applications. Our study suggests that a low cost GOFC without a Nafion electrolyte and noble metal electrodes could be fabricated in the near future. GO is a promising material because of its many excellent chemical and physical properties, which arise from various oxygenated functional groups.1-6 Multi-layered GO nanosheets (GO paper) exhibit high proton conduction. [7][8][9] The main oxygenated functional group in GO is epoxide. It acts as the site for proton transfer after water molecules bind to it, even at low RH and room temperature. 10 The relatively high proton conductivity under these conditions suggests that GO paper could act as a proton electrolyte in various cells and batteries. [11][12][13][14][15][16] The proton conductivity of the GO paper is lower than that of the conventional Nafion electrolyte, which is usually used at high RH (∼100%), 17,18 while the overall conduction of the GO paper will be similar to that of Nafion if the GO paper is less than a tenth of the thickness of the Nafion.It has been reported that various gases do not pass through the GO paper, even when the GO is very thin (0.1 μm).19 This means thin GO paper is well suited as an electrolyte for the H 2 /O 2 fuel cell, because of the high proton conduction and the H 2 and O 2 gas shielding. Nafion electrolytes must be thick in order to achieve gas shielding (>10 2 μm). Moreover, GO paper is much cheaper than Nafion. A mixture of GO paper and Nafion has been used as the electrolyte for a fuel cell, and it acted as an electrolyte even at relatively low RH (25%).8 Sulfonic acid functionalized GO (SGO) has been used as an electrolyte without Nafion, and tested in a H 2 /O 2 fuel cell at 25% RH and 40• C, with Pt/C electrodes. 12Here we report the performance of a simple H 2 /O 2 fuel cells with a 100% GO paper (< 1 atom% S) electrolyte (GOFC) as well as the proton conductivities at low RH and 23-25• C. ExperimentalSynthesis of GO and nanoGO.-The GO was prepared f...

Super proton/electron mixed conduction in graphene oxide hybrids by intercalating sulfate ions

“…We also showed that such membranes composed of nano GO sheets exhibited an approximately 2 times larger current density than the one using micrometer size GO sheets. 19 Another way is to introduce many tiny pinholes in a membrane using highly ozonated GO, which led to significantly improved proton conductivity probably because the pinholes acted as proton conduction channels. 14 We believe that the promising properties of the r-sGO films, including high mixed conductivity, room temperature operability, and good flexibility, would allow for their wide uses in fuel cells, supercapacitors, and gas separation membranes.…”

Anhydrous proton exchange membranes comprising of chitosan and phosphorylated graphene oxide for elevated temperature fuel cells

“…Considering the function of "bridge", 2D sheet filler shows unique inherent superiority due to its large surface area and high aspect ratio. Graphene oxide (GO), single-atom thick 2D sheet structure, electronic insulation, and high proton conduction, should be an active nanofiller in PEMs [27][28][29][30]. The oxygen containing groups (e.g., epoxy and hydroxyl groups on basal planes, carboxylic acid groups) enable GO to be further modified by chemical reactions to introduce various functional groups [31,32].…”

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