Synergistic Remediation of Organic Dye by Titanium Dioxide/Reduced Graphene Oxide Nanocomposite

Martina Kocijan; Lidija Ćurković; Damjan Vengust; Tina Radošević; Vasyl Shvalya; Gil Gonçalves; Matejka Podlogar

doi:10.3390/molecules28217326

Synergistic Remediation of Organic Dye by Titanium Dioxide/Reduced Graphene Oxide Nanocomposite

Molecules. 2023 Oct 29;28(21):7326. doi: 10.3390/molecules28217326.

Authors

Martina Kocijan¹, Lidija Ćurković¹, Damjan Vengust², Tina Radošević³, Vasyl Shvalya⁴, Gil Gonçalves^{5

6}, Matejka Podlogar³

Affiliations

¹ Department of Materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia.
² Advanced Materials Department, Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana, Slovenia.
³ Department for Nanostructured Materials, Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana, Slovenia.
⁴ Department of Gaseous Electronics, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia.
⁵ Centre for Mechanical Technology and Automation (TEMA), Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal.
⁶ Intelligent Systems Associate Laboratory (LASI), 4800-058 Guimarães, Portugal.

Abstract

In this work, nanocomposites based on titanium dioxide and reduced graphene oxide (TiO₂@rGO) with different weight percentages of rGO (4, 8, and 16 wt%) were prepared by the hydrothermal/solvothermal synthesis method and thermally treated at 300 °C. The prepared nanocomposites were explored for the removal of methylene blue dye (MB) in the presence of simulated solar illumination as well as natural sunlight. The structural, morphological, chemical, and optical properties of the as-synthesized TiO₂@rGO nanocomposites were characterized. The obtained results of the graphene-based nanocomposite materials indicated the existence of interactions between TiO₂ and rGO, i.e., the Ti-O-C bond, which confirmed the successful integration of both components to form the TiO₂@rGO nanocomposites. The addition of rGO increased the specific surface area, decreased the band gap energy, and increased the photocatalytic degradation efficiency of MB from water compared to TiO₂ nanoparticles. The results of photocatalytic activity indicated that the amount of rGO in the prepared TiO₂@rGO nanocomposites played a significant role in the application of different photocatalytic parameters, including the initial dye concentration, catalyst concentration, water environment, and illumination source. Our studies show that the reinforcement of the nanocomposite with 8 wt% of rGO allowed us to obtain the maximum photocatalytic decomposition performance of MB (10 mg·L^-1) with a removal percentage of 99.20 after 2 h. Additionally, the obtained results show that the prepared TiO₂@rGO_8 wt% nanocomposite can be used in three consecutive cycles while maintaining photocatalytic activity over 90%.

Keywords: TiO2@rGO; methylene blue; photocatalysis; water environments.

Grants and funding

G.G. thanks the FCT for the Programme Stimulus of Scientific Employment—Individual Support (CEECIND/01913/2017) and the financial support of project CAR-BONCT (2022.03596.PTDC). The financial support of TEMA is also acknowledged by the projects UIDB/00481/2020 and UIDP/00481/2020 from FCT and CENTRO-01-0145-FEDER-022083—Centro Portugal Regional Operational Programme (Centro 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. The financial support of the Slovenian Research Agency is gratefully acknowledged (Project No. L2-1830 and Program No. P2-0084).