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

Mohamed Amine Dahamni,Mostefa Ghamnia,Didier Tonneau,Abed Bouadi,Salah Eddine Naceri,Jean-Jacques Pireaux,Carole Fauquet

doi:10.3390/coatings11050598

Abstract

Pure and Mg-doped manganese oxide thin films were synthesized on heated glass substrates using the spray pyrolysis technique. The surface chemical composition was investigated by the use of X-ray photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). Optical properties were characterized by UV-visible spectroscopy. XPS spectra showed typical Mn (2p3/2), (2p1/2) and O (1s) peaks of Mn3O4 with a slight shift attributed to the formation of different chemical states of manganese. XRD analysis revealed the tetragonal phase of Mn3O4 with a preferred (211) growth orientation that improved with Mg-doping; likewise, grain size is observed to increase with the Mg doping. SEM images of Mn3O4 films showed rough surfaces composed of uniformly distributed nanograins whose size decreases with the Mg-doping. The manganese oxide films surface observed in AFM show a textured, rough and porous surface. The combination of transmittance and absorption data in the UV-visible range allowed determining the energy values of the Eg band gap (1.5–2.5 eV). The decrease of the band gap with the Mg-doping increase is attributed to the influence of the greater size of the Mg2+ ion in the manganese oxide lattice.

Highlights

Published: 19 May 2021Oxides in nanometric films have received increasing interest to the potential applications that derive from their interesting electrical, magnetic and catalytic properties.Manganese oxides in nanometric films are intriguing compounds possessing excellent electrochemical activity allowing it to be used in electrochemistry applications
Due to the three Mn2+, Mn3+ and Mn4+ different oxidative states of manganese, the manganese oxide compound exists in four structures (MnO, Mn2 O3, MnO2 and Mn3 O4 ) [1], which all present interesting physical and chemical properties as important as those of the metal oxides materials (ZnO, SnO2, NiO, CuO, . . . ) belonging to the transparent conducting oxides (TCO) family
Manganese oxide thin films are well suited for various applications such as in optoelectronic applications for their use in solar energy conversion [2,3], electrochemical capacitors [4,5], batteries, sensors [6], chemical sensors [7,8], magnetoelectronic devices, electrochemical energy storage devices and catalytic activity [9,10,11]

Summary

Introduction

Oxides in nanometric films have received increasing interest to the potential applications that derive from their interesting electrical, magnetic and catalytic properties. Manganese oxides in nanometric films are intriguing compounds possessing excellent electrochemical activity allowing it to be used in electrochemistry applications. Quality manganese oxide thin films are relatively easy to prepare, with many physical and chemical techniques such as atomic layer deposition [12], co-precipitation [13], sputtering [14], Molecular Beam. Epitaxy [15], chemical vapor deposition [16] and spray pyrolysis [17,18] It has been shown earlier [19,20] that, amongst these techniques, spray pyrolysis presents many advantages: Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations

Methods

Results

Conclusion