Spray Pyrolysis Synthesis of Pure and Mg-Doped Manganese Oxide Thin Films

Synthesis and Investigation of Pure and Cu-Doped NiO Nanofilms for Future Applications in Wastewater Treatment Rejected by Textile Industry

Pure and Cu-doped NiO films were synthesized via a soft chemical process. They were deposited on glass substrates heated to 400 °C. Different atomic percentage ratios (2, 4, 6, 8, and 10%) of Cu-doping were used. The prepared samples were characterized by several techniques such as X-ray diffraction for crystallographic study, SEM and AFM for microstructural and morphological properties, and UV-Visible spectroscopy for optical and photocatalytical analysis. XRD results of pure and Cu-doped NiO films indicated the formation of NiO polycrystalline phases under a cubic structure with a favored orientation along the (200) plane noticed in all sprayed films. SEM images revealed the formation of NiO nanoparticles of spherical forms whose sizes increase and agglomerate with increasing Cu-doping. At 10% Cu-doping, NiO agglomeration was extended to the whole surface. AFM images showed a textured and rough surface composed of NiO nanoparticles of average size varying from 16 to 10 nm depending on Cu-doping concentration. UV-visible spectroscopy confirmed the transparency of NiO films and their semiconducting character with a band gap ranging from 3.4450 eV to 2.8648 eV. The photocatalytical properties of pure and Cu-NiO films were enhanced by Cu-doping particles as revealed by the degradation of methylene blue (MB) solution subjected to irradiation.

Characterization of Some Physical and Photocatalytic Properties of CuO Nanofilms Synthesized by a Gentle Chemical Technique

Pure and Li-doped CuO nanofilms were synthesized on heated glass substrates using the spray-pyrolysis technique. The deposited pure CuO nanofilms were achieved at a precursor molarity of 0.2 M using a solution prepared from copper nitrate trihydrate (Cu(NO3)2·3H2O). Doped Li–CuO nanofilms were obtained using several doping concentrations (3, 6, 9, 12 and 15%) by adding a solution prepared from lithium nitrate (LiNO3). The pure and Li–CuO samples were investigated by different techniques. XRD revealed three dominant peaks (-111), (111) and (211), which are the properties of monoclinic CuO. The increase in Li-doping concentration showed the appearance of other peaks of low intensities detected at 2θ ranging from 49 to 68°. AFM images showed a textured and inhomogeneous surface composed of spherical grains whose size decreased with increasing Li doping. UV–visible spectroscopy showed that the CuO samples were of low transparency; the transmittance was less than 50%. The band-gap energy determined from Tauc’s equation plot increased from 2.157 to 3.728 eV with the increase in Li doping. These values correspond well to the band gap of semiconducting CuO. The photocatalytic properties were accelerated by Li doping, as revealed by the discoloration of aqueous methylene-blue (MB) solution under ultraviolet irradiation.