scholarly journals Preparation, characterization and enhanced photocatalytic activity of Ni2+ doped titania under solar light

2010 ◽  
Vol 8 (1) ◽  
pp. 142-148 ◽  
Author(s):  
L. Gomathi Devi ◽  
Nagaraju Kottam ◽  
S. Girish Kumar ◽  
K. Eraiah Rajashekhar
Keyword(s):  
Band Gap ◽  
Anatase Phase ◽  
Sol Gel ◽  
Visible Region ◽  
Analytical Techniques ◽  
Red Shift ◽  
Solar Light ◽  
Spectral Studies ◽  
Doped Titania ◽  
Charge Carrier Trapping

AbstractAnatase TiO2 was prepared by sol-gel method through the hydrolysis of TiCl4. Ni2+ was doped into the TiO2 matrix in the concentration range of 0.02 to 0.1 at.% and characterized by various analytical techniques. Powder X-ray diffraction revealed only anatase phase for all the samples, while diffuse reflectance spectral studies indicated a red shift in the band gap absorption to the visible region. The photocatalytic activities of these photocatalysts were probed for the degradation of methyl orange under natural solar light. The photocatalyst with optimum doping of 0.08 at.% Ni2+, showed enhanced activity, which is attributed to: (i) effective separation of charge carriers and (ii) large red shift in the band gap to visible region. The influence of crystallite size and dopant concentration on the charge carrier trapping — recombination dynamics is investigated.

scholarly journals Influence of mild Cr3+ doping on the structural, optical, photochromic, and thermochromic reversibility of nano-titania systems

2019 ◽  
Vol 97 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Rizwin Khanam ◽  
Dambarudhar Mohanta
Keyword(s):  
Band Gap ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Incident Radiation ◽  
Optical Absorption Spectroscopy ◽  
Smart Windows ◽  
Cell Parameters ◽  
Doped Titania ◽  
Reversible Thermochromism

We report on the effect of chromium doping on the band gap lowering of nano-titania (TiO2) and subsequent implications as regards coloration characteristics mediated via photochromism and thermochromism processes. As can be found in the X-ray diffractograms, the sol-gel derived, Cr3+-doped nano-TiO2 systems have exhibited an anatase phase with the evidence of peak shifting towards a lower diffraction angle. The average crystallite size decreases, whereas lattice unit cell parameters and, consequently, cell volume, tend to increase with the inclusion of Cr3+ into the titania host. To be specific, 1% Cr-doped titania system showed nearly 5.8% cell expansion as compared to its un-doped counterpart. As revealed from the optical absorption spectroscopy, a narrowing of band gap is observed for the Cr doped nano-titania system: 3.18 eV for the un-doped system, and 2.61 and 2.41 eV for 0.3% and 1% Cr doping cases, respectively, considering direct band-to-band transitions. Moreover, doping led noticeable lowering of the exponent (n value), from its normal value, which suggests inclusion of adequate non-parabolicity feature to the energy band scheme. The photochromic feature, for a given incident radiation, demonstrates a lowered transmission response with increasing Cr content. A reversible thermochromism response has also been demonstrated for doped nano-titania systems subjected to heating with temperature varying between 0–55 °C. The Cr3+ doped nano-titania and similar systems would find scope in smart windows, display components, photocatalysis, etc., when a select coloration is desired.

Preparation of TiO2 Nanoparticles Doped with Cs+ and Sr2+ and Their Photocatalytic Activity under Solar Light

2010 ◽  
Vol 113-116 ◽  
pp. 1945-1950 ◽  
Author(s):  
Jie Luo ◽  
Xin Yuan Yang ◽  
De Liang Li
Keyword(s):  
Photocatalytic Activity ◽  
Anatase Phase ◽  
Sol Gel ◽  
Visible Region ◽  
Solar Light ◽  
Tetrabutyl Titanate ◽  
Strontium Nitrate ◽  
Doped Tio2 ◽  
As Doping ◽  
Xrd Patterns

Using cesium nitrate and strontium nitrate as doping metal ions source, Cs-doped TiO2 and Sr-doped TiO2 photocatalysts were successfully synthesized through the hydrolysis of tetrabutyl titanate by an acid-catalyzed sol-gel method. The photocatalytic activities of these catalysts prepared at 600 °C for 2 h were evaluated by the degradation of methyl orange in aqueous solution under solar light irradiation, and the as-prepared samples with higher photocatalytic efficiency were characterized by means of X-ray diffraction (XRD) and UV-Vis absorption spectroscopy. The XRD patterns indicate that the crystal structure still remains as anatase phase for the doped samples, and the average crystal size of TiO2, 0.1 at% Cs-doped TiO2 and 0.3 at% Sr-doped TiO2 is 21.3, 13.1 and 10.8 nm, respectively. The band gap absorption shows red shift to the visible region for the doped samples from the UV-Vis spectrogram. The results show that the photocatalytic activity of TiO2 nanoparticles doped with Cs+ and Sr2+ exhibits a significant improvement and their degradation efficiencies are more than 30% in comparison with those of TiO2 under the same condition, and the optimal doping concentration is determined to be 0.1 at% and 0.3 at% for Cs+ and Sr2+, respectively.

scholarly journals Visible Light Induced Photocatalytic Degradation of Methyl Red with Codoped Titania

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Susmitha Thota ◽  
Siva Rao Tirukkovalluri ◽  
Sreedhar Bojja
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Anatase Phase ◽  
Sol Gel ◽  
Visible Region ◽  
Oxygen Demand ◽  
Analytical Techniques ◽  
Active Species ◽  
Methyl Red ◽  
X Ray

Photocatalysis using semiconductor oxides was being investigated extensively for the degradation of dyes in effluent water. This paper reports our findings on visible light induced photocatalytic degradation of azo dye, methyl red mediated nitrogen and manganese codoped nano-titanium dioxide (N/Mn-TiO2). The codoped samples with varying weight percentages were synthesized by sol-gel method and characterized by various analytical techniques. The X-ray diffraction data showed that the synthesized samples were in anatase phase with 2θ at 25.3°. UV-visible diffuse reflectance spectral analysis revealed that the presence of dopants in TiO2 caused a significant absorption shift towards visible region and their presence was confirmed by X-ray photoelectron spectral data. The release of hydroxyl radical (major active species in photocatalytic degradation) by the photocatalyst in aqueous solution under visible light irradiation was quantitatively investigated by the photoluminiscent technique (PL). The effect of various experimental parameters like dopant concentration, pH, catalyst dosage, and initial dye concentrations was investigated and optimum conditions were established. The extent of mineralization of methyl red was studied by chemical oxygen demand (COD) assays and the results showed complete mineralization of the dye.

scholarly journals Effect of Synthesis Conditions of Nitrogen and Platinum Co-Doped Titania Films on the Photocatalytic Performance under Simulated Solar Light

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1074
Author(s):  
Daryna Ihnatiuk ◽  
Camilla Tossi ◽  
Ilkka Tittonen ◽  
Oksana Linnik
Keyword(s):  
Sol Gel ◽  
Visible Region ◽  
Solar Light ◽  
Photocatalytic Decomposition ◽  
Homogeneous Distribution ◽  
Synthesis Conditions ◽  
Simulated Solar Light ◽  
Titania Films ◽  
Doped Titania ◽  
Co Doped

Platinum and nitrogen co-doped titania films of different surface morphologies obtained via a sol-gel process have been tested for tetracycline hydrochloride photocatalytic decomposition under simulated solar light. Titania crystallization to anatase is shown by XRD for all films. A shift of the bandgap edge toward the visible region in absorption spectra and, consequently, a narrowing of the bandgap is observed for some films doped with nitrogen and/or exposed to UV pretreatment. The surface peculiarities of the samples are presented by an SEM and TEM investigation. The surface saturation by Pt and N with a homogeneous distribution of Pt ions on the surface as well as bulk as established by XPS and EDS data can be achieved with a certain synthesis procedure. The influence of the platinum content and of the pretreatment procedure on the state and atomic surface concentration of incorporated nitrogen and platinum is studied by XPS analysis: substitutional and interstitial nitrogen, non-metal containing fragments, Pt0, Pt2+ and Pt4+ ions. The photocatalytic activity of the films is ruled by the presence of Pt2+ ions and N rather than Pt0. The formation of the polycrystalline titania structure and Pt0 nanoparticles (NPs) is confirmed by TEM and electron diffraction images. The mechanism of primary photocatalytic processes is proposed.

scholarly journals Degradation of Typical Indoor Air Pollutants Using Fe-Doped TiO2Thin Film under Daylight Illumination

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Shuaijie Wang ◽  
Hao Yu ◽  
Xingxing Cheng
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Visible Region ◽  
Preparation Condition ◽  
Solar Light ◽  
Photocatalytic Reaction ◽  
X Ray Diffraction ◽  
Vis Spectroscopy ◽  
Doped Titania ◽  
Indoor Air Pollutants

A type of iron-doped titania thin film was prepared by means of sol-gel method to degrade indoor formaldehyde (HCHO), ammonia (NH3), and benzene (C6H6) under sunlight. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and energy dispersive spetra (EDS). The results showed that the iron was doped in the TiO2photocatalyst successfully. The absorption edge of doped TiO2had red shifts and the doped TiO2had a stronger absorption than the pure TiO2in the visible region. Fe-doped TiO2thin film prepared with the optimal preparation condition could remove indoor HCHO, NH3and C6H6effectively under solar light irradiation. The removal percentage of HCHO, NH3or C6H6after 9 h photocatalytic reaction under solar light reached 55%, 53.1%, and 37.5%, respectively, when they existed in the air individually. When the three pollutants were mixed in the air, the removal percentage decreased to 33.3%, 28.3%, and 28%. The degradation reaction of the three pollutants followed the pseudo first-order kinetics, which reflects that the photocatalytic reaction was controlled by the surface chemical reaction and the reaction rate was controlled by concentration of reactants.

Photocatalytic Degradation of Methylene Blue by NiO Thin Films under Solar Light Irradiation

2019 ◽  
Vol 56 ◽  
pp. 152-157 ◽  
Author(s):  
Abdelouahab Noua ◽  
Hichem Farh ◽  
Rebai Guemini ◽  
Oussama Zaoui ◽  
Tarek Diab Ounis ◽  
...  
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Sol Gel ◽  
Visible Region ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Light Irradiation ◽  
Solar Light ◽  
Solar Light Irradiation

Nickel oxide (NiO) thin films were successfully deposited by sol-gel dip-coating method on glass substrates. The structural, morphological and optical properties in addition to the photocatalytic activity of the prepared films were investigated. The results show that the films have a polycrystalline NiO cubic structure with dense NiO grains and average optical transmittance in the visible region. The photocatalytic properties of the films were studied through the degradation of methylene blue and 89% of degradation was achieved for 4.5h of solar light irradiation exposure which indicates the capability of NiO photocatalytic activity.

Aqueous colloidal sol–gel route to synthesize nanosized ceria-doped titania having high surface area and increased anatase phase stability

2007 ◽  
Vol 43 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Pradeepan Periyat ◽  
K. V. Baiju ◽  
P. Mukundan ◽  
P. Krishna Pillai ◽  
K. G. K. Warrier
Keyword(s):  
Surface Area ◽  
Phase Stability ◽  
Anatase Phase ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Doped Titania

scholarly journals Effects in Band Gap for Photocatalysis in TiO2 Support by Adding Gold and Ruthenium

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1032
Author(s):  
Omar Ricardo Fonseca-Cervantes ◽  
Alejandro Pérez-Larios ◽  
Víctor Hugo Romero Arellano ◽  
Belkis Sulbaran-Rangel ◽  
Carlos Alberto Guzmán González
Keyword(s):  
Beneficial Effect ◽  
Band Gap ◽  
Sol Gel ◽  
Visible Region ◽  
Ultra Violet ◽  
Reduced Form ◽  
Nano Catalyst ◽  
Tio2 Support ◽  
The Impact ◽  
Insight Into

One of the key features of a nano catalyst for photocatalysis is the band gap, because, through its analysis, the potential of the catalyst can be determined. In this investigation, the impact on the band gap of different catalysts made by the sol–gel method, compared with TiO2 P25 Sigma-Aldrich, showing the effect of using gold or ruthenium as a metal supported on TiO2, with two different dosage percentages of 1 and 3 percent, was analysed. Additionally, two oxidation states of the catalyst, the reduced form and the oxidized form of the metal, were used to see the effect on the band gap. The experiments show that the gold addition has a higher beneficial effect on the band gap for the UV region (ultra violet region), and the ruthenium addition has a higher beneficial effect for the UV/visible region. The preferred oxidation state for the band gap was the oxidized state. The characterisation of the catalyst provided an insight into the relation between the band gap and the catalyst itself.

Enhancing the Efficiency of Dye Sensitized Solar Cells by Using Anatase and Brookite Mixed Phases of TiO2

2019 ◽  
Vol 14 (11) ◽  
pp. 1582-1588 ◽  
Author(s):  
M. I. Khan ◽  
Shahnawaz ◽  
Shahid Imran ◽  
Muhammad Waqas Yousaf ◽  
A. Wahab ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Anatase Phase ◽  
Sol Gel ◽  
Dye Sensitized Solar Cells ◽  
Visible Region ◽  
Mixed Phase ◽  
Solar Simulator ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

The phases of TiO2 have an important role in the efficiency of dye sensitized solar cells (DSSCs). In this research, the effects of anatase and mixed phases (brookite and anatase) of TiO2 on the efficiency of DSSCs have been reported. 2% Cu doped TiO2 (Cu:TiO2) thin films are prepared by sol–gel dip coating technique. These films are annealed at the temperatures of "350 °C, 450 °C, 550 °C and 650 °C." XRD showed that at 550 °C and 650 °C, films have mixed phases of TiO2. Also, it showed that grain size is increased by increasing temperature. No extra phases of Cu like CuO etc. were observed in XRD graphs, which confirmed that Cu is completely dissolved into TiO2. UV-Vis results showed that all the films have more than 80% transmittance in the visible region. The optical band gap energy (Eg) of films at "350 °C, 450 °C, 550 °C and 650 °C" is 3.96, 3.81, 3.75 and 3.64 eV, respectively. The electrical resistivity of these thin films by four point probe technique is calculated as 121.8 × 102 Ω-m, 95.69 × 102 Ω-m, 86.65 × 102 Ω-m and 76.3 × 102Ω-m respectively. Solar simulator results showed that the current density (Jsc) of mixed phase is higher than single phase, causing higher efficiency. The maximum Jsc 5.12 mAcm–2 is achieved at 650 °C (mixed phase), resulting in higher efficiency of 2.35% which is more than 100 times the efficiency of anatase phase which has 1.18%. This work will provide a way to enhance the efficiency of DSSCs by using mixed phases of TiO2. In future, if 1-D structure of these mixed phases is used in DSSCs then efficiency of DSSCs will improve definitely (or positively).

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