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Tuning photodegradation performance using carbon quantum dots and niobium pentoxide

Spessato, Lucas ; Crespo, Lucas H.S. ; Silva, Marcela C. ; Gibin, Mariana S. ; Sato, Francielle ; Winkler, Manuel E.G. ; Almeida, Vitor C.

Journal of materials science & technology, 2024-08, Vol.191, p.157-167 [Periódico revisado por pares]

Elsevier Ltd

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  • Título:
    Tuning photodegradation performance using carbon quantum dots and niobium pentoxide
  • Autor: Spessato, Lucas ; Crespo, Lucas H.S. ; Silva, Marcela C. ; Gibin, Mariana S. ; Sato, Francielle ; Winkler, Manuel E.G. ; Almeida, Vitor C.
  • Assuntos: Acerola bagasse ; Carbon dots ; Chemical kinetics ; Malachite green ; Photocatalyst
  • É parte de: Journal of materials science & technology, 2024-08, Vol.191, p.157-167
  • Descrição: •Carbon quantum dots (CQD) from acerola bagasse were synthesized.•CQD efficiently enhances the electrical conductivity of Nb2O5.•The composite CQD/Nb2O5 showed high efficiency for malachite green (MG) photodegradation.•The MG photodegradation mechanism is governed by •OH and O2•− radicals. Carbon quantum dots (CQD) were employed as dopants to enhance the photocatalytic efficiency of Nb2O5 by decreasing the bandgap energy and prolonging the lifetime of the photogenerated exciton by increasing conductivity. X-ray diffraction (XRD), N2 porosimetry, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), photoacoustic spectroscopy (PAS), X-ray photoelectron spectroscopy (XPS), Dynamic Light Scattering (DLS), zeta potential, and atomic force microscopy (AFM) were used to characterize the synthesized nanostructures. The residues from acerola processing were converted into CQD with an average size of 2.56 nm, as confirmed by AFM and the high fluorescence quantum yield of 43.32 %. N2 physisorption results showed that the CQD were deposited on the surface of Nb2O5, reducing the specific surface area (SBET) from 122±2.0 to 29±1.3 m² g–1. The photocatalytic performance of CQD/Nb2O5 was superior to that of the control materials under UV−vis light irradiation, as there was a decrease in the bandgap energy (Eg) from 2.78 to 1.93 eV. This decrease in Eg led to a significant increase in the apparent rate constant (kapp) of the MG dye from 1.90 × 10–3 s–1 to 42.2 × 10–3 s–1, demonstrating that the presence of CQD can effectively separate the photogenerated charge carriers, as it was observed from the increase in conductivity showed by Nyquist diagram. [Display omitted]
  • Editor: Elsevier Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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