Magnetic resonance study of annealed and rinsed N-doped TiO2 nanoparticles

AbstractNanoparticles of nitrogen-modified TiO2 (N-doped TiO2) calcined at 300°C and 350°C, have been prepared with and without water rinsing. Samples were characterized by x-ray diffractrometry (XRD) and optical spectroscopy. The electron paramagnetic resonance (EPR) spectra from centers involving oxygen vacancies were recorded for all samples. These could be attributed to paramagnetic surface centers of the hole type, for example to paramagnetic oxygen radicals O−, O2−etc. The concentration of these centers increased after water rising and it further increased for samples annealed at higher temperature. Additionally, for samples calcined at 300°C, and calcined at 350°C and rinsed, the EPR spectra evidenced the presence of magnetic clusters of Ti3+ ions. The photocatalytic activity of samples was studied towards phenol decomposition under unltraviolet-visible (UV-Vis) irradiation. It was found that, in comparison to the starting materials, the rinsed materials showed increased photocatalytic activity towards phenol oxidation. The light absorption (UV-Vis/DRS) as well as surface Fourier transform infrared/diffuse reflectance spectroscopy (FTIR/DR) studies confirmed a significantly enhanced light absorption and the presence of nitrogen groups on the photocatalysts surfaces, respectively. A significant increase of concentration of paramagnetic centers connected with oxygen vacancies after water rising has had an essential influence on increasing their photocatalytic activity.

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Improved light absorption and photocatalytic activity of Zn,N-TiO2−x rich in oxygen vacancies synthesized by nitridation and hydrogenation

New Journal of Chemistry ◽

10.1039/c4nj02132k ◽

2015 ◽

Vol 39 (4) ◽

pp. 2417-2420 ◽

Cited By ~ 8

Author(s):

Yidong Hu ◽

Gang Chen ◽

Chunmei Li ◽

Yaoguang Yu ◽

Jingxue Sun ◽

...

Keyword(s):

Photocatalytic Activity ◽

Light Absorption ◽

Oxygen Vacancies ◽

High Photocatalytic Activity

Compared with N-TiO2 and Zn,N-TiO2 samples, Zn,N-TiO2−x rich in oxygen vacancies demonstrates high photocatalytic activity.

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Hydrothermal Synthesis of Iodine-Doped Nanoplates with Enhanced Visible and Ultraviolet-Induced Photocatalytic Activities

International Journal of Photoenergy ◽

10.1155/2012/915386 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 5

Author(s):

Jiang Zhang ◽

Zheng-Hong Huang ◽

Yong Xu ◽

Feiyu Kang

Keyword(s):

Photocatalytic Activity ◽

Photoelectron Spectroscopy ◽

Oxygen Vacancies ◽

Diffuse Reflectance Spectroscopy ◽

Synergetic Effect ◽

X Ray Diffraction ◽

X Ray ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

Photocatalytic Activities

The iodine-doped Bi2WO6(I-BWO) photocatalyst was prepared via a hydrothermal method using potassium iodide as the source of iodine. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of I-BWO for the degradation of rhodamine B (RhB) was higher than that of pure BWO and I2-BWO regardless of visible light (>420 nm) or ultraviolet light (<400 nm) irradiation. The results of DRS analysis showed that the I-BWO and I2-BWO catalysts had narrower band gaps. XPS analysis proved that the multivalent iodine species including I0and were coadsorbed on the defect surface of Bi2WO6in I-BWO. The enhanced PL intensity revealed that a large number of defects of oxygen vacancies were formed by the doping of iodine. The enhanced photocatalytic activity of I-BWO for degradation of RhB was caused by the synergetic effect of a small crystalline size, a narrow band gap, and plenty of oxygen vacancies.

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Photocatalytic Degradation of Estriol Using Iron-Doped TiO2 under High and Low UV-Irradiation

10.20944/preprints201809.0583.v1 ◽

2018 ◽

Author(s):

Irwing M. Ramírez-Sánchez ◽

Erick R. Bandala

Keyword(s):

Photocatalytic Activity ◽

Electron Microscope ◽

Uv Irradiation ◽

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

Bet Surface Area ◽

Doped Tio2 ◽

X Ray ◽

Transmission Electron ◽

Iron Doped

Iron Doped TiO2 nanoparticles (Fe-TiO2) were synthesized and photocatalitically investigated under high and low fluence values of UV-radiation. The Fe-TiO2 physical characterization was performed using X-ray Powder Diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Diffuse Reflectance Spectroscopy (DRS), and X-Ray Photoelectron Spectroscopy (XPS) technique. The XPS evidenced that ferric ion (Fe3+) was in the lattice of TiO2 and co-dopants no intentionally added were also present due to the precursors of the synthetic method. The Fe3+ concentration played a key role in the photocatalytic generation of hydroxyl radical (•OH) and estriol (E3) degradation. Fe-TiO2 materials accomplished E3 degradation, and it was found that the catalyst with 0.3 at. % content of Fe (0.3 Fe-TiO2) enhanced the photocatalytic activity under low UV-irradiation compared with no intentionally Fe-added TiO2 (zero-iron TiO2) and Aeroxide® TiO2 P25. Furthermore, the enhanced photocatalytic activity of 0.3 Fe-TiO2 under low UV-irradiation may have applications when radiation intensity must be controlled, as in medical applications, or when strong UV absorbing species are present in water.

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Preparation and Characterization of Defective TiO2. The Effect of the Reaction Environment on Titanium Vacancies Formation

Materials ◽

10.3390/ma13122763 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2763

Author(s):

Zuzanna Bielan ◽

Szymon Dudziak ◽

Agnieszka Sulowska ◽

Daniel Pelczarski ◽

Jacek Ryl ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

Hydrothermal Reaction ◽

High Photocatalytic Activity ◽

Paramagnetic Resonance ◽

X Ray ◽

Light Activity ◽

Cheap Alternative

Among various methods of improving visible light activity of titanium(IV) oxide, the formation of defects and vacancies (both oxygen and titanium) in the crystal structure of TiO2 is an easy and relatively cheap alternative to improve the photocatalytic activity. In the presented work, visible light active defective TiO2 was obtained by the hydrothermal reaction in the presence of three different oxidizing agents: HIO3, H2O2, and HNO3. Further study on the effect of used oxidant and calcination temperature on the physicochemical and photocatalytic properties of defective TiO2 was performed. Obtained nanostructures were characterized by X-ray diffractometry (XRD), specific surface area (BET) measurements, UV-Vis diffuse reflectance spectroscopy (DR-UV/Vis), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. Degradation of phenol as a model pollutant was measured in the range of UV-Vis and Vis irradiation, demonstrating a significant increase of photocatalytic activity of defective TiO2 samples above 420 nm, comparing to non-defected TiO2. Correlation of EPR, UV-Vis, PL, and photodegradation results revealed that the optimum concentration of HIO3 to achieve high photocatalytic activity was in the range of 20–50 mol%. Above that dosage, titanium vacancies amount is too high, and the obtained materials’ photoactivity was significantly decreased. Studies on the photocatalytic mechanism using defective TiO2 have also shown that •O2− radical is mainly responsible for pollutant degradation.

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Visible-light photocatalysis on C-doped ZnO derived from polymer-assisted pyrolysis

RSC Advances ◽

10.1039/c4ra17227b ◽

2015 ◽

Vol 5 (35) ◽

pp. 27690-27698 ◽

Cited By ~ 93

Author(s):

Ahmad S. Alshammari ◽

Lina Chi ◽

Xiaoping Chen ◽

Abdulaziz Bagabas ◽

Denis Kramer ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Light Absorption ◽

Oxygen Vacancies ◽

Charge Carriers ◽

Visible Light Photocatalysis ◽

Visible Light Absorption ◽

C Doping ◽

Doped Zno

Heavy C-doping can effectively enhance visible-light absorption yet exhibited lower visible-light-responsive photocatalytic activity due to significant recombination of photogenerated charge carriers caused by C-dopant and oxygen vacancies.

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Synthesis of Nanocrystalline InVO4 by Hydrothermal Process and its Visible-Light Photocatalytic Activity

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.734 ◽

2011 ◽

Vol 284-286 ◽

pp. 734-737 ◽

Cited By ~ 3

Author(s):

Pei Song Tang ◽

Hai Feng Chen ◽

Feng Cao ◽

Guo Xiang Pan ◽

Kun Yan Wang

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Light Absorption ◽

Diffuse Reflectance Spectroscopy ◽

Hydrothermal Process ◽

X Ray Diffraction ◽

Visible Light Absorption ◽

Visible Light Photocatalytic Activity ◽

Hydrothermal Approach ◽

Visible Light Photocatalytic

Monophasic orthorhombic InVO4 was synthesized using InCl3 and NH4VO3 as starting materials by a hydrothermal approach. The as-prepared InVO4 product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). It was found that the as-prepared InVO4 shows strong visible-light absorption with absorption onset of 515 nm, indicating a narrow optical band gap of 2.4 eV. Furthermore, the as-prepared InVO4 shows high visible-light photocatalytic activity for decomposition of methyl orange, which is ascribed to the strong visible-light absorption.

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Controlling the synergistic effect of oxygen vacancies and N dopants to enhance photocatalytic activity of N-doped TiO2 by H2 reduction

Applied Catalysis A General ◽

10.1016/j.apcata.2012.03.008 ◽

2012 ◽

Vol 425-426 ◽

pp. 117-124 ◽

Cited By ~ 59

Author(s):

Zizhong Zhang ◽

Jinlin Long ◽

Xiuqiang Xie ◽

Huaqiang Zhuang ◽

Yangen Zhou ◽

...

Keyword(s):

Photocatalytic Activity ◽

Synergistic Effect ◽

Oxygen Vacancies ◽

Doped Tio2 ◽

Effect Of Oxygen

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Visible-Light Driven LaNiO3 Nanosized Photocatalysts Prepared by a Sol-Gel Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.279.83 ◽

2011 ◽

Vol 279 ◽

pp. 83-87 ◽

Cited By ~ 7

Author(s):

Pei Song Tang ◽

He Sun ◽

Feng Cao ◽

Jin Tian Yang ◽

Sheng Liang Ni ◽

...

Keyword(s):

Photocatalytic Activity ◽

Methyl Orange ◽

Visible Light ◽

Light Absorption ◽

Diffuse Reflectance Spectroscopy ◽

Sol Gel ◽

High Photocatalytic Activity ◽

Visible Light Absorption ◽

Average Grain Size ◽

Sol Gel Process

The LaNiO3 nanoparticles were prepared by a sol-gel process. The LaNiO3 nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). XRD and SEM demonstrate the successful synthesis of single phase perovskite LaNiO3 and an average grain size of 80 nm in diameter. It was found that the as-prepared LaNiO3 shows strong visible-light absorption with absorption onset of 545 nm, indicating a narrow optical band gap of 2.28 eV. Consequently, LaNiO3 nanoparticles show high visible-light photocatalytic activity for decomposition of methyl orange in comparison with the commercial Degussa P25. The photocatalytic experiment shows the high photocatalytic activity for the decomposition of methyl orange under visible-light irradiation, which is attributed to the strong visible-light absorption.

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