Bi-functional photocatalytic heterostructures combining titania thin films with carbon quantum dots (C-QDs/TiO2) for effective elimination of water pollutants

Pinelopi P Falara; Islam Ibrahim; Adamantia Zourou; Labrini Sygellou; David Emanuel Sanchez; George Em Romanos; Lida Givalou; Maria Antoniadou; Michalis K Arfanis; Changseok Han; Mauricio Terrones; Konstantinos V Kordatos

doi:10.1007/s11356-023-27285-7

Bi-functional photocatalytic heterostructures combining titania thin films with carbon quantum dots (C-QDs/TiO₂) for effective elimination of water pollutants

Environ Sci Pollut Res Int. 2023 Dec;30(60):124976-124991. doi: 10.1007/s11356-023-27285-7. Epub 2023 May 10.

Authors

Pinelopi P Falara^{1

2}, Islam Ibrahim^{2

3}, Adamantia Zourou¹, Labrini Sygellou⁴, David Emanuel Sanchez⁵, George Em Romanos², Lida Givalou^{1

2}, Maria Antoniadou^{2

6}, Michalis K Arfanis², Changseok Han^{7

8}, Mauricio Terrones^{5

9

10}, Konstantinos V Kordatos¹¹

Affiliations

¹ School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou St., 15780 Zografou, Athens, Greece.
² Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece.
³ Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, Cairo, 11884, Egypt.
⁴ Foundation of Research and Technology Hellas, Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), POB 1414, GR-26504, Patras, Greece.
⁵ Department of Materials Science and Engineering and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA.
⁶ Department of Chemical Engineering, University of Western Macedonia, ZEP, 50100, Kozani, Greece.
⁷ Department of Environmental Engineering, INHA University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, South Korea.
⁸ Program in Environmental & Polymer Engineering, Graduate School of INHA University, 100 Inha-ro, Michuhol-gu, Incheon, 22212, South Korea.
⁹ Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
¹⁰ Department of Chemistry and Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA.
¹¹ School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou St., 15780 Zografou, Athens, Greece. kordatos@mail.ntua.gr.

Abstract

In this study, carbon quantum dots (C-QDs), prepared via hydrothermal-microwave procedures, were successfully combined with nanostructured titania (TiO₂). The photocatalytic oxidation/reduction activity of the C-QDs/TiO₂ composite films was evaluated in the decomposition of organic-inorganic contaminants from aqueous solutions under UV illumination. Physicochemical characterizations were applied to investigate the crystal structure of the carbon quantum dots and the composites. It was found that the prepared C-QDs/TiO₂ composites had great contribution to the photocatalytic reduction of hexavalent chromium (Cr⁺⁶) species and 4-Nitrophenol (PNP) as well as to the photocatalytic oxidation of methylene blue (MB) and Rhodamine B (RhB) dyes. The mechanism of the photocatalytic reaction was studied with trapping experiments, revealing that the electron (e^-) radical species were powerfully supported for the photocatalytic reduction of Cr⁺⁶ and PNP and the holes (h⁺) are the main active species for the photocatalytic oxidation reactions.

Keywords: C-QDs/TiO2 composite; Carbon quantum dots; Organic-inorganic pollutants; Photocatalytic degradation; Reusability experiments; Synthesis.

MeSH terms

Carbon
Quantum Dots* / chemistry
Water Pollutants*
Water Pollutants, Chemical* / analysis

Substances

titanium dioxide
Water Pollutants
Carbon
Water Pollutants, Chemical