Hydrothermally Preparation and Characterization of Un-doped Manganese Oxide Nanostructures: Efficient Photocatalysis and Chemical Sensing Applications

Manganese oxide nano-particles have been synthesized by hydrothermal process using aqueous combination of manganese chloride and urea as starting materials, where ammonium hydroxide is used as a reducing agent to adjust the pH at 10.55. The structural investigation of the as-grown nano-crystalline manganese oxide is analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrophotometer (FTIR), and Raman spectrophotometer, which revealed that the synthesized manganese oxide is well crystalline. Further, energy dispersive spectroscopy (EDS) confirms the composition of manganese oxide (Mn3O4) with Mn and O elements. UV-Visible absorption spectra (~293.44 nm) are used to investigate the optical properties of as-grown Mn3O4. The photocatalytic activity of the synthesized Mn3O4 is evaluated using color dye (Acridine Orange, AO), which degraded close to 47.38% in irradiation time (170 min). The chemical sensing of Mn3O4 coated electrodes has been primarily investigated by I-V technique, where ethanol is used as a model compound. The analytical performance of ethanol sensors exhibits the higher sensitivity (0.4777 μAcm-2mM-1) and a large linear dynamic range (0.17 μM to 0.17 M) in short response time (10.0 sec). Keywords: Mn3O4, XRD, FE-SEM, Photo-degradation, Acridine Orange, Ethanol sensor