Hydrogen production by membrane water electrolysis has attracted tremendous attention because of its benefits, which include easy separation of hydrogen and oxygen, no carbon emissions, and the possibility to store hydrogen fuel as an electricity source. Here, we study water vapor electrolysis using a proton-conducting membrane comprising graphene oxide (GO) nanosheets. The GO membrane shows good through-plane proton conductivity, as confirmed by concentrationcell measurements, complex impedance spectroscopy, and hydrogen pumping experiments. The results also confirm that most carriers in the GO membrane are protons. The GO membrane fitted with Pt/C and IrO2-Al2O3 as the cathode and the anode, respectively, efficiently electrolyzes humidified air to produce hydrogen and oxygen at room temperature, which indicates bright prospects for this carbon-based electrochemical device.

Graphene oxide (GO) is an ultrathin carbon nanosheet with various oxygen-containing functional groups. The utilization of GO has attracted tremendous attention in a number of areas, such as electronics, optics, optoelectronics, catalysis, and bioengineering. Here, we report the development of GO-based solid electrolyte gas sensors that can continuously detect combustible gases at low concentrations. GO membranes were fabricated by filtration using a colloidal solution containing GO nanosheets synthesized by a modified Hummers’ method. The GO membrane exposed to humid air showed good proton-conducting properties at room temperature, as confirmed by hydrogen concentration cell measurements and complex impedance analyses. Gas sensor devices were fabricated using the GO membrane fitted with a Pt/C sensing electrode. The gas-sensing properties were examined by potentiometric and amperometric techniques. The GO sensor showed high, stable, and reproducible responses to hydrogen at parts per million concentrations in humid air at room temperature. The sensing mechanism is explained in terms of the mixed-potential theory. Our results suggest the promising capability of GO for the electrochemical detection of combustible gases.

Graphene oxide (GO) nanosheets with high protonic conductivity were used for electrochemical detection of hydrogen. The sensor based on a GO membrane attached with a Pt/C sensing electrode and a Pt black reference electrode showed good electromotive force (EMF) response to hydrogen in ppm concentrations in air at room temperature. The EMF changes were highly dependent on type of sensing materials and the Pt/C electrode gave high sensor responses in dry and wet conditions. Large EMF variations with changing H2 concentration were observed, indicating the promising capability of GO for on-line monitoring of hydrogen leakage.