Effects of hydrothermal treatment of cellulose nanocrystal templated TiO2 films on their photodegradation activity of methylene blue, methyl orange, and rhodamine B

Y. H. Yoon, S. Y. Lee, J. G. Gwon, E. Vijayakumar, H. G. Lee, W. H. Lee

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Transparent mesoporous TiO2 films with enhanced photocatalytic degradation efficiency were systematically synthesized. The films were prepared using a mixed sol containing a cellulose nanocrystal (CNC) template that was spin-coated onto an ITO substrate, followed by calcination at 400 °C for 1 h. Subsequently, the fabricated films were subjected to hydrothermal treatment in a pure aqueous medium for various periods of time (1, 2, and 4 h) and at different temperatures (150 and 250 °C). The surface area and crystallite size of the prepared TiO2 film were increased and decreased from 76.7 m2/g and 12.78 nm (without the template) to 127.3 m2/g and 9.95 nm (with the template), and then to 233.4 m2/g and 4.43 nm (1 h and 150 °C) with hydrothermal treatment, respectively. Hydrothermal treatment plays an important role in enlarging the surface area, and decreasing the crystallite size. Furthermore, the optimized TiO2 film exhibits exceptional photodegradation activity towards organic dyes with performance nearly equal to that of the standard photocatalyst. Because of the exceptional properties of the prepared optimized TiO2 film, the adsorption of organic dyes on its surface increases, which promotes the photocatalytic degradation efficiency during light irradiation.

Original languageEnglish
Pages (from-to)2911-2922
Number of pages12
JournalCeramics International
Volume49
Issue number2
DOIs
Publication statusPublished - 2023 Jan 15

Bibliographical note

Funding Information:
The above-mentioned results support the BET results and SEM morphology of the prepared CNC–TiO2. Fig. 5(c) exhibits the optical microscopy images of the pure TiO2, CNC–TiO2, H1501h–CNC–TiO2, and H2501h–CNC–TiO2 films, and the corresponding progressive load scratch test results of the prepared films are plotted in Fig. 5(d). The calculated values are also listed in Table 1. The results of the progressive load scratch test analyses show that the TiO2 films coated on the ITO substrate with and without the CNC template are less durable than the films that were subsequently treated hydrothermally. However, the scratch test results indicate that the scratch hardness of the CNC–TiO2 (30.8 mN) film is slightly lower than that of the pure TiO2 film (32.5 mN). This indicates that the higher surface roughness and greater thickness of CNC–TiO2 (compared with the pure TiO2 film) may be indicative of the occurrence of high internal stress during scratch loading [54]. Large areas of spalling beyond the residual groove indicate weak adhesion and cohesion strength between the coating and the substrate, resulting in adhesion failure [55]. However, the films that were treated hydrothermally had exceptionally high scratch hardness values (H1501h–CNC–TiO2: 47.5 mN, H2501h–CNC–TiO2: 52.1 mN), which were more well aligned with the surface roughness results (AFM analysis of H1501h–CNC–TiO2: Ra = 2.57 nm, Rq = 3.30 nm; H2501h–CNC–TiO2: Ra = 2.40 nm, Rq = 3.09 nm) of the hydrothermally treated films. This suggests that the hydrothermal treatment provides excellent surface adhesion superior to that of pure TiO2 and CNC–TiO2. The excellent adhesion between the substrate and films enhances the stability for use in various applications. Gemic et al. also discovered that the hydrothermal treatment of films composed of nanoparticles improved the scratch hardness and led to exceptional mechanical durability [56].

Publisher Copyright:
© 2022 Elsevier Ltd and Techna Group S.r.l.

Keywords

  • Cellulose nanocrystals
  • Hydrothermal
  • Mesoporous
  • Photo-degradation
  • Titania

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry

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