Ethanol sensing properties and photocatalytic degradation of methylene blue by Mn3O4, NiMn2O4 and alloys of Ni-manganates thin films

Abstract

This work highlights the sensitivity properties of thin films based on nickel manganese oxides (NiMnO) which were grown by the spray pyrolysis technique on glass substrates at T = 350 °C. First, the films were characterized by XRD and Raman spectroscopy in order to identify their phases and microstructures. Results of these measurements prove that at a percentage of nickel element Ni/Mn equal to 33%, Mn3O4 thin film was changed to the pure nickel manganese ternary oxide NiMn2O4. Both UV–Vis–NIR spectrophotometry measurements and the room temperature photoluminescence (PL) spectra of NiMnO thin films confirm the dependence of the optical band gap (Eg) with Ni content. Second, NiMnO thin films exhibit a promising photocatalytic activity for the degradation of methylene blue (MB) dye. The DC conductivity based ethanol sensing measurements showed that the pure NiMn2O4 and Mn3O4 thin film have ready clear sensing response toward ethanol vapor. Finally, these materials may be of interest for other gas and organic pollutants.