Synthesis of a nitrogen-doped titanium dioxide–reduced graphene oxide nanocomposite for photocatalysis under visible light irradiation--颗粒学报PARTICUOLOGY

Vahidzadeh, E., Fatemi, S., & Nouralishahi, A. (2018). Synthesis of a nitrogen-doped titanium dioxide–reduced graphene oxide nanocomposite for photocatalysis under visible light irradiation. Particuology, 41, 48-57. https://doi.org/10.1016/j.partic.2017.12.013

Synthesis of a nitrogen-doped titanium dioxide–reduced graphene oxide nanocomposite for photocatalysis under visible light irradiation

Ehsan Vahidzadeh ^a, Shohreh Fatemi ^a *, Amideddin Nouralishahi ^b

a School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran, Iran
b Caspian Faculty of Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran, Iran

10.1016/j.partic.2017.12.013

Volume 41, December 2018, Pages 48-57

Received 22 August 2017, Revised 10 December 2017, Accepted 13 December 2017, Available online 21 May 2018, Version of Record 1 November 2018.

E-mail: shfatemi@ut.ac.ir

Highlights

• Hydrothermal method followed by NH₃ gaseous treatment were applied for N-TiO₂–RGO production.

• Nitrogen was doped in both lattice structures of TiO₂ and reduced graphene oxide of the composite.

• The synthesized N-TiO₂–RGO was used as photocatalyst under visible light for dilute VOCs removal.

Abstract

A nitrogen-doped titanium dioxide–reduced graphene oxide (N-TiO₂–RGO) nanocomposite has been synthesized by the combination of a hydrothermal method and a thermal treatment under a NH₃/N₂ atmosphere. The resulting composites are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, diffuse reflectance absorption spectroscopy, energy-dispersive X-ray spectroscopy, and Raman characterization techniques. The sequence of the thermal treatment and hydrothermal treatment processes is shown to influence the photocatalytic activity of nitrogen-doped composites. The composites synthesized by using this method show better photocatalytic activities toward the degradation of acetaldehyde under visible light irradiation compared with P25, N-TiO₂, and TiO₂–RGO. By applying the thermal treatment process after the hydrothermal process, nitrogen atoms can be simultaneously doped in the lattice of TiO₂ nanoparticles and on the surface of reduced graphene oxide sheets. The conversion of acetaldehyde, as the model molecule of volatile organic compounds, is measured in a continuous stirred-tank reactor until the steady state condition is reached. The conversion of 50 ppm acetaldehyde, in an air flow under illumination from an 80 W Hg lamp with a UV cut-off filter, reaches 62% after a 1-h reaction using a 0.07 g N-TiO₂–RGO sample with an optimum loading of 2 wt% graphene oxide. In comparison, the photocatalytic activity of P25 for the degradation of acetaldehyde under visible light irradiation is only 8% under the same reaction conditions. The reaction rates for acetaldehyde degradation are calculated and predicted with pseudo-first-order reaction kinetics, and the activity result of the best N-TiO₂–RGO sample is 12.3 times higher than for P25.

Graphical abstract

Keywords

N-doped TiO₂; Photocatalyst; Reduced graphene oxide; Visible light irradiation; Nanocomposite; Nanoparticle

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