Title: Effect of N₂ plasma treatment on TiO₂ thin films for photocatalysis application

Authors: Lazhari-Ayoub Naas; Boudjemaa Bouaouina; Kamel Mokeddem; Fayçal Bensouici; Noureddine Selmi; Nabil Khelifati; Seddik Elhak Abaidia

Addresses: Laboratoire Revêtement, Matériaux and Environnement, Department of Physics, M'hamed Bougara University of Boumerdès, Boumerdès 35000, Algeria ' Laboratoire Revêtement, Matériaux and Environnement, Department of Physics, M'hamed Bougara University of Boumerdès, Boumerdès 35000, Algeria ' Laboratoire Revêtement, Matériaux and Environnement, Department of Physics, M'hamed Bougara University of Boumerdès, Boumerdès 35000, Algeria ' Department of Materials Science, Abbas Laghrour University, Khenchela 40004, Algeria ' Nuclear Research Centre of Birine, Ain Oussera BO 17200 Djelfa, Algeria ' Centre de Recherche en Technologie des Semi-conducteurs pour l'Energétique, Alger 16000, Algeria ' Laboratoire Revêtement, Matériaux and Environnement, Department of Physics, M'hamed Bougara University of Boumerdès, Boumerdès 35000, Algeria

Abstract: TiO₂ thin films were prepared via a spin-coating technique and subsequently treated with nitrogen plasma discharge at varying gas pressures. X-ray diffraction analysis revealed characteristic peaks of the TiO₂ anatase phase. Atomic force microscopy (AFM) analysis demonstrated uniformly smooth surface profiles, with an increase in the sharpness of surface features following N₂ plasma treatment. UV-visible analysis indicated high transparency levels within the range of 80%-90%. Moreover, an incremental flow of nitrogen gas led to a slight reduction in the energy band gap from 3.4 to 3.2 eV. Photoluminescence emissions were detected, attributed to intrinsic emission and surface defect states. The nitrogen plasma treatment also resulted in a reduction in electrical sheet resistivity from 35 to 17 Ω. Contact angle measurements confirmed the super-hydrophilicity of the nitrogen plasma-treated TiO₂ thin films. Furthermore, the impact on the photocatalytic activity of the treated TiO₂ films was found to be minimal.

Keywords: TiO₂ thin films; sol-gel processes; plasma treatment; photocatalysis; plasma discharge; atomic force microscopy; AFM.

DOI: 10.1504/IJMATEI.2025.145079

International Journal of Materials Engineering Innovation, 2025 Vol.16 No.1, pp.78 - 92

Received: 13 Oct 2023
Accepted: 20 Jan 2024
Published online: 18 Mar 2025 *