Effect of Interlayer Distance and Oxygen Content on Proton Conductivity of Graphite Oxide

Abstract

The effect of interlayer distance and oxygen content on proton conductivity of graphite oxide is presented. Bulk-state proton conductivities were measured using coin-shaped pellets of three different graphite oxide samples, namely, H-GO, S-GO, and B-GO, generated respectively from the techniques of Hummers, Staudenmaier, and Brodie. The extent of oxidation, nature of functional groups, interlayer distances, and morphologies are studied through Raman spectroscopy, XPS, powder XRD pattern, and SEM images. The proton conductivities follow the trend H-GO > S-GO > B-GO. In the XPS study, the total oxygen contents were found to follow the trend H-GO > B-GO > S-GO, whereas the interlayer distances obtained from the powder XRD patterns show the trend H-GO > S-GO > B-GO. Beside the nature of the functional groups and extent of oxidation, the interlayer distance displays a significant effect on the proton conductivity values. The temperature-dependent Arrhenius plots reveal the activation energy (E a ) of the samples as 0.274, 0.291, and 0.296 eV. These low E a values imply the Grotthuss mechanism for proton conduction. The high conductivity value and low activation energy of H-GO with a maximum interlayer distance indicate that hydronium ion's rotational movement and re-formation of hydrogen bonds by the Grotthuss mechanism are supported by a more flexible interlayer. We propose that this physical insight might be considered to improve the proton conductivity through modulating layer distances not only in carbon allotropes but also in other materials.

Hybrids from the π−π Stacking of Graphene Oxide and Aromatic Sulfonic Compounds for Improved Proton Conductivity

“…The peak around 169 eV exists for S2p of sulfo group. Peaks from 284 to 290 eV show the existence of C1s spectra, which is associated with C−C, C=C bonds and oxygen functional groups including C−OH, C−O−C and C=O (Figure S2) . The PXRD data confirmed the variation in the interlayer distances of GO and the hybrids (Figure c).…”

“…The proton conductivities of GO‐based materials usually increase due to the improvement in both the hydrophilicity of surfaces and flexibility of interlayers. The improved hydrophilicity supports increased water adsorption process, while a flexible interlayer can support improved hydrodynamics and faster reformation of hydrogen bond networks . Both these phenomenon are essential for faster proton transfer process.…”

Chemical, Thermal, and Light-Driven Reduction of Graphene Oxide: Approach to Obtain Graphene and its Functional Hybrids

“…Peak ratio (I D /I G ) gradually increases for G → GO; however, decreases along the conversion: GO → GO/GO-metal ion hybrids → G/Gmetal oxide hybrids. The I D /I G value changes proportionally with the extent of sp 2 domain [34,35]. Thus, the gradual decrease in I D /I G value implies expansion of this domain.…”

Water Adsorption and Transport on Oxidized Two‐Dimensional Carbon Materials

“…In earlier stages, bulk graphite oxide (GO′) was used as a filler for polymer electrolytes, and the sulfonic acid‐functionalized GO′/Nafion composite showed a higher conductivity than GO′ powder . The dependency of the proton conductivity of GO′ pellet on oxygen content and interlayer distance was studied carefully, with the results suggesting that proton conductivity could be improved by modulating the layer spacing in carbon allotropes and other layered materials . However, all of these studies involved bulk samples or composites, and the in‐plane ionic conductivity of pure GO nanosheets was unknown.…”

“…As the aqueous solution of GO turned out to be acidic, protons generated through the reaction of water molecules with the GO surface functional groups result in a decrease in the electrical impedance. Previously, the measured proton conductivity was found to be affected by both the interlayer distance and oxygen content of the materials . In particular, carboxylic groups enable an increase in interlayer distances and support faster proton conduction through the improved hydration dynamics.…”