Electrochemical deposited Mg-PPy multilayered film to store hydrogen

Abstract

The stability of magnesium and its hydride (Mg/MgH2) against moisture and oxygen can be improved by forming a multilayered structure with a protective polymeric layer. Herein, we report for the first time the fabrication of such a multilayered structure via an electrochemical deposition method consisting of the successive depositions of Mg on electropolymerised polypyrrole (PPy) films. The thickness of the PPy and the Mg layers was ∼1 μm, which is larger than the Mg/Pd multilayers prepared via physical deposition methods, owing to the higher surface roughness of electropolymerised films. However, such films displayed remarkable hydrogen storage properties. Hydrogenation of the PPy/Mg film was achieved at 100 °C and hydrogen release started from 125 °C with a peak at ∼215 °C. When covered by a second PPy layer, the hydrogen desorption temperature increased slightly to 230 °C. These hydrogen absorption and desorption temperatures are significantly lower than that of pristine Mg/MgH2 micron sized powders and this was achieved without any additional catalyst. Furthermore, such hydrogenated PPy/Mg/PPy film structures were found to be stable in air even after one week.