Enhancement of reversible hydrogen capacity into activated carbon through water electrolysis

The amount of hydrogen reversibly stored on an activated carbon electrode u sing electrodecomposition of 6 mol.L-1 KOH aqueous solution has been invest igated. 1.5 wt % of hydrogen was released from carbon during the oxidation process, with a well-defined plateau at ca. -0.5 V vs. Hg/HgO. This is high er than the amount adsorbed under ambient gas atmosphere. This enhancement is thought to be due to the formation of nascent hydrogen during water redu ction, which penetrates easily in the carbon nanostructure. Our results sho w that not only carbon nanotubes should be considered as hydrogen reservoir and that low cost materials such as activated carbons could be convenient in appropriate conditions. (C) 2001 The Electrochemical Society.