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. 2019 May 9;9(5):720.
doi: 10.3390/nano9050720.

Enhanced Photocatalytic Degradation of Organic Dyes via Defect-Rich TiO2 Prepared by Dielectric Barrier Discharge Plasma

Yanqin Li  1 , Wei Wang  2 , Fu Wang  3 , Lanbo Di  4 , Shengchao Yang  5 , Shengjie Zhu  6 , Yongbin Yao  7 , Cunhua Ma  8 , Bin Dai  9 , Feng Yu  10
Affiliations

Enhanced Photocatalytic Degradation of Organic Dyes via Defect-Rich TiO2 Prepared by Dielectric Barrier Discharge Plasma

Yanqin Li et al. Nanomaterials (Basel). .

Abstract

The dye wastewater produced in the printing and dyeing industry causes serious harm to the natural environment. TiO2 usually shows photocatalytic degradation of dye under the irradiation ultravilet light rather than visible light. In this work, a large number of oxygen vacancies and Ti3+ defects were generated on the surface of the TiO2 nanoparticles via Ar plasma. Compared with pristine TiO2 nanoparticles, the as-obtained Ar plasma-treated TiO2 (Ar-TiO2) nanoparticles make the energy band gap reduce from 3.21 eV to 3.17 eV and exhibit enhanced photocatalytic degradation of organic dyes. The Ar-TiO2 obtained exhibited excellent degradation properties of methyl orange (MO); the degradation rate under sunlight irradiation was 99.6% in 30 min, and the photocatalytic performance was about twice that of the original TiO2 nanoparticles (49%). The degradation rate under visible light (λ > 400 nm) irradiation was 89% in 150 min, and the photocatalytic performance of the Ar-TiO2 was approaching ~4 times higher than that of the original TiO2 nanoparticles (23%). Ar-TiO2 also showed good degradation performance in degrading rhodamine B (Rho B) and methylene blue (MB). We believe that this plasma strategy provides a new method for improving the photocatalytic activity of other metal oxides.

Keywords: defects; organic dye; photocatalytic degradation; plasma; titanium dioxide.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Spectra of (a) X-ray diffractometer (XRD) spectra, (b) Raman spectra, (c) Fourier transforms infrared spectra (FTIR) spectra and (d) BET spectra for the Ar-TiO2 and pristine TiO2 catalysts. Insert: the N2 adsorption-desorption isotherms.
Figure 2
Figure 2
X-ray photoelectron spectroscopy (XPS) spectra of (a) survey spectra, (b) O 1s, (c) Ti 2p and (d) Electron paramagnetic resonance (EPR) spectra for the Ar-TiO2 and pristine TiO2 catalysts.
Figure 3
Figure 3
(a) Ultraviolet (UV)-visible absorption spectra DRS, the insets in Figure 3 (a) is the corresponding plots of transformed Kubelka-Munk function versus the energy of photon, (b) XPS valence band spectra.
Figure 4
Figure 4
Schematic drawing illustrating the mechanism of charge separation and photocatalytic activity of the TiO2 photocatalyst under solar light irradiation.
Figure 5
Figure 5
The results of transmission electron microscopy (TEM) of (a,b) TiO2 and (d,e) Ar-TiO2. High resolution TEM (HRTEM) image curves of (c) TiO2 (inset: SAED) and (f) Ar-TiO2 (insert: SAED).
Figure 6
Figure 6
Removal of (a,b) methyl orange (MO), (c,d) methylene blue (MB) and (e,f) rhodamine B (Rho B) by TiO2 and Ar-TiO2 (inset: corresponding degradation rate images) under solar light and/or visible light (λ ≥ 400 nm) irradiation. Solution concentration: 10 mg/L; organic solution: 100 mL; catalyst: 50 mg.
See this image and copyright information in PMC

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