Electrolytic Hydrogen Release from Hydrogen Boride Sheets

Abstract

Solid‐state hydrogen storage materials are safe and lightweight hydrogen carriers. Among the various solid‐state hydrogen carriers, hydrogen boride (HB) sheets possess a high gravimetric hydrogen capacity (8.5 wt%). However, heating at high temperatures and/or strong ultraviolet illumination is required to release hydrogen (H2) from HB sheets. In this study, the electrochemical H2 release from HB sheets using a dispersion system in an organic solvent without other proton sources is investigated. H2 molecules are released from the HB sheets under the application of a cathodic potential. The Faradaic efficiency for H2 release from HB sheets reached >90%, and the onset potential for H2 release is −0.445 V versus Ag/Ag+, which is more positive than those from other proton sources, such as water or formic acid, under the same electrochemical conditions. The total electrochemically released H2 in a long‐time experiment reached ≈100% of the hydrogen capacity of HB sheets. The H2 release from HB sheets is driven by a small bias; thus, they can be applied as safe and lightweight hydrogen carriers with economical hydrogen release properties.

Visible-Light-Driven Hydrogen Release from Dye-Sensitized Hydrogen Boride Nanosheets

“…Among the various solid-state hydrogen carriers, twodimensional hydrogen boride (HB) nanosheets have been reported and have attracted significant attention because of their high hydrogen density (8.5 wt %). 12 HB nanosheets can release hydrogen by a facile heat treatment at a relatively low temperature under ambient pressure, 12 where H 2 release begins at approximately 423 K. In addition to the heating procedure, H 2 molecules can be released from HB nanosheets by an electrochemical bias application 13 or ultraviolet (UV) light irradiation without any heat input. 14 UV-induced hydrogen release from HB nanosheets is practically useful because its on−off control of H 2 generation can be easily operated only by light irradiation, which reduces the operation energy compared to a system using heat treatment.…”