Tailoring of MgO/Mg(OH)2 structures by molten salt electrolysis

Abstract

The magnesium oxide (MgO)/magnesium hydroxide (Mg(OH)2) nanostructures aside from showing high surface area, good thermal, electrical, optical and chemical characteristics, are also low-cost materials of benign nature with minimal environmental impact, which make them suitable for various application. Due to their specific properties magnesium oxide and magnesium hydroxide are used in medicine, sensors, solar cells, drinking and waste water treatments. Depending on the in advance planned application, considerable attention should be paid to the formation of appropriate magnesium oxide/hydroxide composition and surface morphology. Herein, a novel approach was used to the synthesis of MgO/Mg(OH)2 structures by electrochemical deposition from magnesium nitrate hexahydrate melt onto glassy carbon. Galvanostatic and potentiostaic regimes of electrolysis were employed for direct formation of magnesium oxide. Morphology of the composed structures were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Analysis of the deposits made by both electrolysis regimes recognized formation of magnesium oxide as well as magnesium hydroxide. Comparative study of the deposits morphology showed that nano-sized needles and holes are produced by applied electrodepositions. Most of the needles formed participate in flower-like shapes. The holes observed in the deposit are a product of the hydrogen evolution and in the number, shape and size strongly depend on the deposition parameters applied. During controlled working potential or current density, the detached hydrogen bubbles produced different types of deposit structures, from dish-like to those of the honeycomb-like shape. Formation mechanism of the observed deposits is discussed.Invited lecture, [http://sitzam.org.rs/YUCORR/