Despite the considerable in-plane proton conductivity of graphene oxide (GO) nanosheets, inadequate single-cell performance in a polymer exchange membrane fuel cell (PEMFC) occurred on incorporating a vacuum-filtration-prepared GO membrane between the electrodes. In particular, the proton transfer between the electrodes in the PEMFC single cell is in the out-of-plane direction of the GO membrane and was found to be significantly lower than for the in-plane direction due to the presence of proton conduction barriers arising from turbostratic stacking of the GO layers. Therefore, the structural transformation of GO nanosheets into an ultrafast, out-of-plane proton conductor is key to boosting GO-based PEMFC performance. Here, we report the use of a freeze-dried route to three-dimensional (3D) graphene oxide (3DGO) exhibiting a 3D interconnected network and significant interlayer void space. The out-of-plane direction proton conductivity of 3DGO was calculated to be 3.5 × 10–2 S cm–1 at 343 K and 100% relative humidity (RH), which is about 175 times higher than that for the GO membrane. The 3DGO was incorporated as a solid electrolyte in a PEMFC single cell, and a maximum power density of 60.2 mW cm–2 was obtained at 30 °C. This high proton conductivity and PEMFC performance of the 3DGO are correlated with the facile proton conduction pathway and higher water uptake in the 3D porous architecture of 3DGO.

The efficient removal of radioactive cesium (137Cs) from contaminated water around nuclear plants and/or after nuclear accidents has become an emerging issue since the Fukushima Daiichi Nuclear Power Plant (Fukushima, Japan) disaster on March 11, 2011. Herein, we have demonstrated and compared the adsorption performances of both 137Cs and 133Cs using three potential adsorbents, zeolite (ZL), Prussian blue (PB) and graphene oxide (GO), in deionized water and simulated seawater. The adsorption efficiencies are determined in terms of the adsorbent amount, initial Cs concentration, and the effect of other competing ions in the system. In addition, the practical application of the materials was justified by evaluating the elution/retention of the adsorbed Cs with different volumes of solvent. Significantly, we illustrated a practical validation of a purification route for 137Cs-contaminated fly ash generated from nuclear power plant accidents, while PB can be a potential adsorbent for large-scale implementation.

Ion conduction through graphene oxide nanosheets that is pH-switchable between H+ and OH− ions is demonstrated.

The largest reported dinuclear Fe(ii) triple helicate system to exhibit spin crossover is presented, with exploration of the two-step spin-transition.

Herein we determine the Seebeck coefficients, electric conductivities, and thermoelectric power factors of a range of unreduced graphene oxide (GO)/single-wall carbon nanotube (CNT) membranes incorporating different GO/CNT ratios as well...