Metal organic framework derived nanostructured ferropericlase for waterborne Pb(II) ion sensing and organic dye removal

Highly crystalline and chemically stable bimetallic MgFe mixed oxide of ferro-periclase crystal structure has been derived for the first time from thermal decomposition of Prussian Blue metal organic framework. Scanning electron microscopy images confirmed formation of nanoflake like morphology. N2 adsorption-desorption isotherms indicated mesoporous nature with high specific surface area, suitable for sensing applications. Mott-Schottky studies suggested that the material is a p-type semiconductor and optical characterisation revealed a band gap (of ∼1.9 eV), well within the visible light absorption range suggesting its potential as a photocatalyst. When the as-synthesized MgFe oxide was tested against some common organic contaminants like Methylene blue and Rhodamine B dissolved in water (generally found in water bodies carrying textiles wastes), it was able to remove almost 90% of the cationic dyes within 3 h under low power UV–visible lamps. Moreover, Differential Pulse Voltammetry studies using the MgFe oxide film as working electrode revealed its potential as an electrochemical sensor for detection of heavy metal ions such as Pb(II) as it detected the presence of Pb(II) even at a very low concentration regime of 4–24 ppb. Therefore, this metal oxide composed of earth abundant elements is proposed as a low cost photocatalyst for organic pollutant removal and voltametric sensor for Pb(II) ions.