Enhanced visible photocatalytic performance of un-doped TiO2 nanoparticles thin films through modifying the substrate surface roughness

• Published in: Materials chemistry and physics Vol. 279; p. 125530
• Main Authors: Hosseini, Zahra Sadat, Haghparast, Farzane, Masoudi, Amir Ali, Mortezaali, Abdollah
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.03.2022; Elsevier BV
• Subjects: Catalytic activity; Charge transfer; Crystal defects; Defects; Dip coatings; Energy gap; Glass substrates; Grain boundaries; Heat treatment; Holes (electron deficiencies); Hydrophilicity; Immersion coating; Light emitting diodes; Nanoparticles; Optical properties; Optical property; Photocatalysis; Pollutants; Recyclability; Sol-gel processes; Surface roughness; Thin films; TiO2 nanoparticle; Titanium dioxide; Titanium oxides; Ultraviolet radiation; Visible photocatalytic activity; Surface roughness; Optical property; Visible photocatalytic activity; TiO2 nanoparticle; Defects
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.125530

Titanium oxide (TiO2) has been widely utilized for application in environmental pollution due to its unique properties. However, large bandgap (3.2 eV) and low surface area of bulk TiO2 are the main properties that limit its photocatalytic applications. In this work, a thin layer of TiO2 (<200 nm) nanoparticles (NPs) on mechanically roughened glass substrates is deposited by a simple sol-gel method followed by a dip-coating process along with fast heating and sintering. The effect of substrate surface roughness on the morphology, hydrophilicity, and optical properties which results in a more electron-hole generation and consequently improved photocatalytic activity was investigated by different characterization techniques. The TiO2 layer on the roughest substrate (RMS = 76.90 nm) showed the smallest average NP size (3 nm) with the highest surface roughness (RMS = 121.00 nm) and hydrophilicity (74.5%) as well as strong optical absorption. This sample photodegraded the pollutant with an efficiency of 85% at a rate of 0.0054 min−1 under the illumination of the vis-light emitting diode (LED)-based source (440 and 590 nm). Therefore, an enhanced photocatalytic activity accompanied by recyclability was achieved by modifying the substrate surface roughness and thermal treatment in the process of synthesis. Conclusively, intrinsic defects and grain boundaries appear which behave as active areas for charge transfer in the photocatalytic process under visible irradiation. This research may provide an insight into the fabrication of highly efficient photocatalysts based on commonly used wide band gap materials to work in the absence of UV light. [Display omitted] •Application of a simple process for deposition of visible photoactive TiO2 nanoparticles (NPs) on mechanically roughened glass substrates.•Investigating the effect of substrate roughness on the operating parameters in the visible photocatalytic activity.•Highest photo-degradation of pollutant with an efficiency of 85% at a rate of 0.0054 min−1 under the illumination of the vis-LED for the TiO2 NPs on the substrate with RMS roughness of 76.90 nm.•Explaining the corresponding mechanism for enhancing the visible photo-degradation of TiO2 NPs with roughness.