Increasing Rutile Phase Amount in Chromium-Doped Titania by Simple Stirring Approach for Photodegradation of Methylene Blue under Visible Light

2015 ◽  
Vol 68 (7) ◽  
pp. 1129 ◽  
Author(s):  
Pei Wen Koh ◽  
Leny Yuliati ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Band Gap ◽  
Rutile Phase ◽  
Band Gap Energy ◽  
Synthesis Process ◽  
Doped Tio2 ◽  
Gap Energy ◽  
Stirring Time ◽  
Doped Titania

The amount of rutile phase in chromium-doped titania photocatalyst was controlled by varying stirring time (0.5–2.0 h) at room temperature during a sol–gel synthesis process. The percentage of rutile phase increased from 15.1 % to 28.6 % when stirring time was prolonged from 0.5 to 1.5 h. Further increases in the stirring time had negligible effect on the rutile phase amount. As evidenced by analyses using diffuse reflectance ultraviolet–visible spectroscopy and X-ray photoelectron spectroscopy, a sufficient stirring time was important for more substitution of Cr3+ for Ti4+ in the lattice, resulting in anatase-to-rutile phase transformation. The formation of more rutile phase in Cr-doped TiO2 not only reduced the band gap energy, but also induced surface defects that retarded electron–hole recombination. It has been demonstrated that the Cr-doped TiO2 prepared with a stirring time of 1.5 h possessed the lowest band gap energy of 1.89 eV, and hence it achieved the highest photodegradation of methylene blue under visible light irradiation.

Effect of ZnO on a Superhydrophilic Self-Cleaning Properties of TiO2/SiO2 Thin Film on Glass Slide Substrate

2015 ◽  
Vol 1131 ◽  
pp. 237-241 ◽  
Author(s):  
Akkarat Wongkaew ◽  
Chanida Soontornkallapaki ◽  
Naritsara Amhae ◽  
Wichet Lamai
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Visible Light ◽  
Band Gap ◽  
Sol Gel ◽  
Dip Coating ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Coating Method ◽  
Dip Coating Method

This work aims to study the effect of ZnO containing in TiO2/SiO2 film on the superhydrophilic property after exposed to different types of light. The metal solutions were prepared by sol-gel technique and the film was deposited on glass slides by dip coating method. The parameter studied was the amount of ZnO in the TiO2/SiO2 film. The contents of ZnO were 5-20% weight (increased by 5%). The amount of TiO2 was constant at 30% weight. The obtained films were analyzed for their roughness. The results indicated that film roughness changed according to the ZnO contents. With 5%ZnO in the thin film, the roughness was 0.726 nm while 20%ZnO obtained the roughness of 2.128 nm. UV-Vis spectrophotometer was used for measuring of transmittance of films. At wavelength of 550 nm, the transmittances of each film were greater than 90%. Band gap energy of each film was calculated from the transmittance data. It was found that the average band gap energy of the films was 2.47 eV. Then, the films contained various amount of ZnO were grouped into 2 sets. The first set was exposed to visible light while the other set was exposed to UV. The duration of exposure was 5 hr. Both sets of films after exposed to any light were kept in a black box controlled relative humidity of 85%. Each film was measured contact angle every day. It was found that the 30%TiO2/5%Zn/SiO2 film exposed to visible light showed the best superhydrophilic property. The contact angle was about 0-5° within 3 days. This may due to the reduction of band gap energy in the presence of ZnO in TiO2/SiO2 films to 2.41 eV and the roughness of the film.

Effect of Transition Metal Oxide Doping (Cr, Co, V) in the Photocatalytic Activity of TiO2 for Congo Red Degradation under Visible Light

2014 ◽  
Vol 69 (5) ◽  
Author(s):  
P. W. Koh ◽  
L. Yuliati ◽  
S. L. Lee
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Congo Red ◽  
Sol Gel ◽  
Rutile Phase ◽  
Band Gap Energy ◽  
Electron Recombination ◽  
Doped Tio2 ◽  
Light Region ◽  
Electron Scavenger

Comparative study of Cr, Co or V-doped TiO2 was carried out. The photocatalysts were synthesized via sol-gel method. The results indicated that the dopants of Cr, Co, and V induced anatase to rutile phase transition of TiO2 at different dopant amounts of 1, 4, 2 mol%, respectively. Besides that, the existence of dopant extended the absorption wavelength of TiO2 to visible light region, thus making it a visible-driven photocatalyst. The doped transition metal exhibited different oxidation states on the TiO2 surface. The prepared photocatalysts were tested over photodegradation of Congo Red. Amongst all, Cr-doped TiO2 (3 mol%) was the best photocatalyst attributed to the presence of 45% rutile phase, reduced band gap energy of 2.30 eV and formation of Cr6+, which acted as an electron scavenger to delay the hole-electron recombination. 

N-Loaded TiO2 for Photocatalytic Degradation of Methyl Orange under Visible Light Irradiation

2012 ◽  
Vol 622-623 ◽  
pp. 883-888
Author(s):  
Natkritta Boonprakob ◽  
Natda Wetchakun ◽  
Sukon Phanichphant ◽  
Jun Chen ◽  
Burapat Inceesungvorn
Keyword(s):  
Methyl Orange ◽  
Visible Light ◽  
Band Gap ◽  
Visible Light Irradiation ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Light Irradiation ◽  
Gap Energy ◽  
Visible Light Driven ◽  
Degradation Of Methyl Orange

Nitrogen-loaded TiO2(N-loaded TiO2), a visible-light driven catalyst, was successfully synthesized by the modified sol-gel method. Physical characterizations of the as-prepared catalysts have been performed by using X-ray diffraction (XRD), Diffuse reflectance UVvisspectroscopy(DRUVvis), Raman spectroscopyand BETspecific surface areain order to obtain structure-activity relationship. Results from Raman spectroscopy clearly suggested that N atoms were incorporated into the TiO2crystal lattice as evidenced by the vibrational peak of TiN in TiO2-xNx.DR UVvis results also suggested that the nitrogen dopant might be responsible for narrowing the TiO2band gap energy, thus resulting in a shift towards the visiblelight region. Photocatalytic activity of N-loaded TiO2evaluated through the degradation of methyl orange (MO)under visible light irradiation (l> 400 nm) indicated that all N-loaded photocatalysts exhibited significantly higher activities than the unloaded TiO2and Degussa P25 TiO2. According to the results from DR UV-vis, XRD and BET studies, the enhanced photoactivity observed from N-loaded samples might be due to a decrease in TiO2band gap energy and/or changes in chemical and physical properties of the materials upon loading with nitrogen.

Visible light driven photo-degradation of Congo red by TiO2ZnO/Ag: DFT approach on synergetic effect on band gap energy

Chemosphere ◽  
2018 ◽  
Vol 213 ◽  
pp. 481-497 ◽  
Author(s):  
Carlos Alberto Huerta-Aguilar ◽  
Viviana Palos-Barba ◽  
Pandiyan Thangarasu ◽  
Ranjit T. Koodali
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Congo Red ◽  
Synergetic Effect ◽  
Band Gap Energy ◽  
Photo Degradation ◽  
Gap Energy ◽  
Visible Light Driven

Band Gap Narrowed P Doped 1T@2H MoS2 Nanosheets Towards Synergistically Enhanced Visible Light Photochemical Property

2020 ◽  
Vol 15 (2) ◽  
pp. 257-263 ◽  
Author(s):  
Yipin Wang ◽  
Rongfang Zhang ◽  
Genliang Han ◽  
Xiaoping Gao
Keyword(s):  
Catalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Surface Area ◽  
Hydrothermal Process ◽  
Band Gap Energy ◽  
Commercial Application ◽  
Photochemical Property ◽  
Mos2 Nanosheets ◽  
Gap Energy

The weak transport charge efficiency and great band gap energy of layered MoS2 hamper its further commercial application. To overcome these deficiencies, we report a simple, controlled and handy hydrothermal process for realizing 2H MoS2 to 1T MoS2 transition with P source. Due to the more conductive ability and larger surface area, P-doped 1T@2H MoS2 nanosheets show an outstanding catalytic activity. Noticeably, P-doped 1T@2H MoS2 nanosheets with narrowed bandgap exhibits a remarkable optical photochemical performance. It fully eliminates 50 ml of 20 mg L–1 RhB in 70 minutes with outstanding recycling and structural stability by using 10 mg catalyst.

scholarly journals Dielectric, optical and enhanced photocatalytic properties of CuCrO2 nanoparticles

RSC Advances ◽  
2017 ◽  
Vol 7 (44) ◽  
pp. 27549-27557 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ruby Phul ◽  
Parvez Alam ◽  
Irfan H. Lone ◽  
Mohd. Shahazad ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Surface Area ◽  
Band Gap Energy ◽  
Catalytic Degradation ◽  
Photocatalytic Properties ◽  
Sunlight Irradiation ◽  
Gap Energy ◽  
Precursor Route ◽  
Citrate Precursor

Delafossite CuCrO2 nanoparticles with band gap energy of 3.09 eV and surface area of 235 m2 g−1 were prepared by citrate precursor route showed enhanced catalytic degradation of methylene blue in H2O under the sunlight irradiation.

scholarly journals Photocatalytic Hydrogen Production from Water on Ga, Sn-Doped ZnS under Visible Light Irradiation

2014 ◽  
Vol 925 ◽  
pp. 200-204
Author(s):  
Leny Yuliati ◽  
Melody Kimi ◽  
Mustaffa Shamsuddin
Keyword(s):  
Photocatalytic Activity ◽  
Hydrogen Production ◽  
Visible Light ◽  
Band Gap ◽  
Visible Light Irradiation ◽  
Absorption Edge ◽  
Band Gap Energy ◽  
Light Irradiation ◽  
Photocatalytic Hydrogen Production ◽  
Gap Energy

Zinc sulfide (ZnS) has been reported to act as a photocatalyts to reduce water to hydrogen. However, ZnS could not work under visible light irradiation due to its large band gap energy. In order to improve the performance of ZnS, Ga and Sn were doped to ZnS. The series of Ga (0.1),Sn (x)-ZnS with various amounts of Sn (x) was prepared by hydrothermal method. XRD patterns suggested that the addition of Ga might reduce the crystallinity of ZnS, suggesting that Ga might inhibit the crystal growth or agglomeration of ZnS. On the other hand addition of Sn did not much affect the structure of the Ga (0.1)-ZnS. The DR UU-visible spectra confirmed the red shift of the absorption edge with the addition of Ga due to the reduced band gap energy, while the addition of Sn did not much shift the absorption edge of the Ga (0.1)-ZnS to longer wavelength. FESEM images showed that all the prepared samples have sphere-shaped particles and no remarkable change was observed with the addition of Ga or Sn. The photocatalytic hydrogen production from water was carried out at room temperature in the presence of sacrificial agent under visible light irradiation. While ZnS did not show activity under visible light, all the prepared Ga (0.1)-ZnS and Ga (0.1),Sn (x)-ZnS samples exhibited photocatalytic activity for hydrogen production. The highest hydrogen production was achieved on Ga (0.1),Sn (0.01)-ZnS, which activity was ca. three times higher than that of the single doped Ga (0.1)-ZnS. This study clearly showed that Sn acted as a good co-dopant to increase the photocatalytic activity of Ga (0.1)-ZnS for hydrogen production from water under visible light irradiation.

scholarly journals Synthesis, characterization and photocatalytic activity of Zn2+, Mn2+ and Co2+ doped SnO2 nanoparticles

2019 ◽  
Vol 9 (5) ◽  
pp. 4199-4204 ◽  
Author(s):  
Oeindrila Mukhopadhyay ◽  
Soumita Dhole ◽  
Badal Kumar Mandal ◽  
Fazlur-Rahman Nawaz Khan ◽  
Yong-Chien Ling
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Transition Metal ◽  
Band Gap ◽  
Sno2 Nanoparticles ◽  
Transition Metal Ions ◽  
Band Gap Energy ◽  
Blue Dye ◽  
Gap Energy ◽  
Sno2 Nps

Nanomaterials with many improved properties have been used in versatile applications. Herein we have synthesized SnO2 NPs doped with transition metal ions such as Zn2+, Mn2+ and Co2+ through a facile and inexpensive hydrothermal approach. The synthesized nanomaterials were characterized by XRD, FT-IR, SEM and UV-Vis analysis. The optical properties of the NPs were characterized by using UV–vis and photoluminescence spectroscopy (PLS). Their photocatalytic performances were investigated by degrading methylene blue (MB) dye with UV irradiation. Transition metal doping to SnO2 NPs improved the photocatalytic activity to degradation of methylene blue dye due to tuning of band gap energy i.e. lowering of band gap energy compared to undoped SnO2 NPs. The results suggest that the synthesized NPs could be used efficiently for remediation/degradation of environmentally hazardous dyes from waste water or environmental cleanup.

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