Boosted hydrogen production via binder-assisted immobilization of hydrogen boride sheets on cathodes

Abstract

Hydrogen boride (HB) sheets are attractive solid-state hydrogen carriers because of their safe, lightweight, and light-induced dehydrogenation properties. Previously, electrolytic hydrogen release under cathodic bias was reported for dispersed HB sheets. In this paper, we demonstrate that the immobilization of HB sheets on an electrode enhances their dehydrogenation rates by facilitating direct electron injection from the electrode into the HB sheets. HB sheets were immobilized on a carbon paper electrode using coating solutions containing HB sheets, various polymeric binders, and a solvent. Among various binders, aramid demonstrated excellent adhesion of HB sheets to an electrode and a high hydrogen release rate under cathodic bias. To further enhance the dehydrogenation rate, we have additionally introduced electroconductive graphene into the coating solutions to fix the film of HB sheets/aramid/graphene composites onto carbon electrodes. The optimum weight ratio of HB/aramid/graphene was 1/2/1, yielding a high dehydrogenation rate under cathodic bias. Electrochemical impedance spectroscopy analysis revealed a significant decrease in charge transfer resistance upon the addition of graphene. The present immobilized film provides a superior system compared with the conventional dispersed one for hydrogen release.