Carbon-based potentiometric hydrogen sensor using a proton conducting graphene oxide membrane coupled with a WO3 sensing electrode

Abstract

For the safety use of hydrogen, on-site monitoring of its concentrations in the atmosphere is indispensable when producing, using, and transporting hydrogen. Here, we report that a carbon-based electrochemical device for hydrogen sensing has been realized using a proton conducting graphene oxide (GO) membrane fitted with a composite of tungsten trioxide (WO3) and reduced graphene oxide (rGO) as the sensing electrode. Using concentration cell measurements and proton pumping techniques, we proved that protons can diffuse in a membrane made by stacking GO nanosheets that were synthesized by oxidation and exfoliation of graphite via the Hummers’ method. The GO membrane fitted with WO3-rGO exhibited a good sensor response of more than 50 mV to 100 ppm H2 in air with a response slope of 82 mV/decade at room temperature. The H2 detection limit of the GO device was approximately 11 ppm. The sensing mechanism is explained in terms of the mixed potential theory, in which anodic and cathodic reactions of hydrogen and oxygen, respectively, proceed simultaneously at the interface between GO and WO3-rGO. The device also showed a good stability and selectivity to H2 over other combustible gases such as CO, ethanol, and acetone.