Electrochemical Synthesis of Flower like Magnesium Oxide/Hydroxide from Magnesium Nitrate Melt

Abstract

The magnesium oxide (MgO)/magnesium hydroxide (Mg(OH)2) in recent years have received considerable attention as one of the nanomaterials intended for specific application. The interest in this material is standing from promising utilization in next generation solar cells, advanced catalysis, medicine, toxic waste remediation and similar. More advanced utilizations, however, require controlled surface morphology and composition of the oxy/hydroxide. It is now common knowledge that electrodeposition technique provides a suitable way to obtain materials of micro or nano scales in the desired forms. Additionally, shape and size of the deposited material can be conveniently controlled by the choice of parameters and regimes of electrolysis. A novel approach to electrochemical synthesis of magnesium oxide/hydroxide meso - and nanostructures on glassy carbon electrode from the melt made of magnesium nitrate hexahydrate melt at 100 °C have been considered. The electrodeposition of magnesium oxide/hydroxide commences in magnesium underpotential (UPD) and continues through the magnesium overpotential (OPD) region. Chronoamperometric analysis showed that magnesium oxides/hydroxides syntheses taking part simultaneously at various applied potentials are a result of reactions between magnesium cations and products of water and nitrate anions reduction processes. Chemical reactions responsible for direct formation of magnesium oxide observed are those of magnesium ions and oxygen ions, formed by nitrate reduction taking part in the close vicinity of the working electrode. The morphology of magnesium oxide/hydroxide obtained by galvanostatic regime were characterised using scanning electron microscopy (SEM) technique. Network of individual very thin needles were formed in both magnesium UPD and OPD region, as well as those grouped in flower-like aggregates in magnesium OPD regions, Fig.1