Thermally Stable Super Ionic Conductor from Carbon Sphere Oxide

Thermally stable proton conductivity from nanodiamond oxide

Herein, we report nanodiamond oxide (NDOx), obtained from modified Hummers' oxidation of nanodiamond (ND), showing excellent proton conductivity and thermal stability. NDOx possesses hydrophilicity resulting in higher water adsorption and the retention of functional groups at elevated temperatures can be attributed to the high proton conductivity and thermal stability, respectively.

High Proton Conductivity of 3D Graphene Oxide Intercalated with Aromatic Sulfonic Acids

The development of efficient proton conductors that are capable of high power density, sufficient mechanical strength, and reduced gas permeability is challenging. Herein, we report the development of a series of aromatic sulfonic acid/graphene oxide hybrid membranes incorporating benzene sulfonic acid (BS), naphthalene sulfonic acid (NS), naphthalene disulfonic acid (DS) or pyrene sulfonic acid (PS) using a facile freeze dried method. For out-of-plane proton conductivity, the 3DGO-BS and 3DGO-NS yielded proton conductivities of 4.4×10-2  S cm-1 and 3.1×10-2  S cm-1 , respectively; this represents a two-times higher value than that which occurs for three dimensional graphene oxide (3DGO). Additionally, the respective prepared films as membranes in a proton exchange membrane fuel cell (PEMFC) show maximum power density of 98.76 mW cm-2 for 3DGO-NS while it is 92.75 mW cm-2 for 3DGO-BS which are close to double that obtained for 3DGO (50 mW cm-2 ).

Enhanced mixed proton and electron conductor at room temperature from chemically modified single-wall carbon nanotubes

A chemically modified single-wall carbon nanotube showing efficient mixed proton and electron conduction at room temperature is demonstrated.

Branched Alkylamine-Reduced Graphene Oxide Hybrids as a Dual Proton-Electron Conductor and Organic-Only Water-Splitting Photocatalyst

We report multifunctionalities including the solid electrolytic property, electron conductivity (EnC), and photocatalytic water splitting (PWS) ability of organic-only hybrids obtained by intercalating short and branched-chain alkylamines including methylamine (MA), butylamine (BA), pentylamine (PA), and isomethylbytylamine (IMBA) in reduced graphene oxide (rGO). The alkylamine-rGO hybrids were synthesized by a facile solid-state reduction process. Within the series, IMBA-rGO exhibited high proton conductivity (PrC), EnC, and optimized PWS capacity. The PrC of IMBA-rGO was from 10^-4 to 10^-3 S cm^-1, which is only half an order less than that for pristine GO. The EnC was 1.25 μA/V. Though the PWS performances of MA-rGO, BA-rGO, and PA-rGO were comparatively lower, IMBA-rGO could generate about 1.5 times H₂ compared with that for R-TiO₂. The IR spectra indicate the association of IMBA and GO by chemical bonds. The Raman spectra show the transformation of GO's nonconductive sp³ carbon sites into electron-conductive sp² carbon centers. The thermogravimetric analysis show improved water adsorbing capacity of IMBA-rGO, which resulted in higher PrC. Doping of the nitrogen atom at the graphitic sp² system was confirmed from the presence of pyrrolic N in X-ray photoelectron spectroscopy spectra. The resultant N-type semiconducting behavior is majorly responsible for the PWS process. The powder X-ray diffraction analysis indicates a more flexible interlayer space in IMBA-rGO, which facilitates both the reformation of hydrogen bonds during proton conduction and water dynamics during photocatalysis. The material indicates the possibility of devising graphene-based organic-only multifunctional hybrids.

Development of an All Solid State Battery Incorporating Graphene Oxide as Proton Conductor

Graphene oxide (GO) shows high proton conductivity (≈10-4 Scm-1), excellent mechanical stability, and electrical insulation property, which makes it an ideal candidate for use as a proton conducting solid state electrolyte. The prospects of using GO as single phase solid electrolyte in an all solid battery is presented herein. A battery with the cell configuration: Zn + ZnSO4•7H2O + graphite (anode) || GO (electrolyte) || MnO2 + graphite (cathode) is fabricated. Cyclic voltammetry confirms its rechargeable nature. The respective discharge capacity and power density of the cell are 360 μAh and 19.5 mW kg-1 at a constant current drain of 3 μA under the experimental conditions employed. GO based proton conductors are cleaner and cheaper than other solid electrolytes. The current study strongly suggests that GO can be used as a practical and beneficial component in solid state battery applications with low energy feedback.

Role of hydrophilic groups in acid intercalated graphene oxide as a superionic conductor

The role of hydrophilic groups in acid intercalated GO for proton conduction has been justified. The higher extents of adsorbed water due to the presence of hydrophilic groups are primarily responsible for offering enhanced proton conductivity.

Proton Conductivity of Graphene Oxide on Aging

The aging effect on the proton conductivity of graphene oxide (GO) is investigated. Characterizations of oxygenated functional groups and measurement of the proton conductivity have been performed using freshly prepared GO and the same sample after preserving for three years under ambient conditions. Although GO retains its layered structure, a slight deviation in its powder X-ray diffraction (PXRD) pattern and Raman spectra upon aging implies some changes in the interlayer distance and functional groups. Decomposition of epoxy groups on aging has been recognised by X-ray photoelectron spectroscopy (XPS) analysis. The proton conductivity was found to be reduced by 25 % after three years of aging.