The catalytic effect of Nb 2O 5 on the electrochemical hydrogenation of nanocrystalline magnesium

Abstract

Nanocrystalline Mg powder without and with 2 mol% Nb 2O 5 catalyst was studied in a 6 M KOH electrolyte as electrode material for electrochemical hydrogen charging processes. Since the hydrogen overpotential of Mg, which is a measure of the hydrogen evolution at the electrode surface, was observed to be reduced by the addition of Nb 2O 5, it is assumed that the catalyst influences the electrode reactions. Considering this assumption hydrogenation was studied at different current densities. The storage capacity as well as the kinetic of Mg/Nb 2O 5 electrodes increased significantly up to 1 wt.% H 2 at a charging time of 30 min with decreasing current density. The storage capacity of nanocrystalline Mg powder showed only minor changes to lower hydrogen contents with decreasing current density.