V-doped TiO2 Nanoparticles Research Articles

Enhanced electrochemical properties of Zn and V-doped TiO2 nanoparticles synthesized via non-aqueous sol–gel route for supercapacitor application

Enhanced electrochemical properties of Zn and V-doped TiO2 nanoparticles synthesized via non-aqueous sol–gel route for supercapacitor application

Expression of Concern: Synthesis and characterization of V-doped TiO2 nanoparticles through polyol method with enhanced photocatalytic activities

Expression of Concern: Synthesis and characterization of V-doped TiO2 nanoparticles through polyol method with enhanced photocatalytic activities

Ultrafast optical spectroscopy of semiconducting and plasmonic nanostructures and their hybrids

The knowledge of the carrier dynamics in nanostructures is of fundamental importance for the development of (opto)electronic devices. This is true for semiconducting nanostructures as well as for plasmonic nanoparticles (NPs). Indeed, improvement of photocatalytic efficiencies by combining semiconductor and plasmonic nanostructures is one of the reasons why their ultrafast dynamics are intensively studied. In this work, we will review our activity on ultrafast spectroscopy in nanostructures carried out in the recently established EuroFEL Support Laboratory. We have investigated the dynamical plasmonic responses of metal NPs both in solution and in 2D and 3D arrays on surfaces, with particular attention being paid to the effects of the NP shape and to the conversion of absorbed light into heat on a nano-localized scale. We will summarize the results obtained on the carrier dynamics in nanostructured perovskites with emphasis on the hot-carrier dynamics and in semiconductor nanosystems such as ZnSe and Si nanowires, with particular attention to the band-gap bleaching dynamics. Subsequently, the study of semiconductor-metal NP hybrids, such as CeO2-Ag NPs, ZnSe-Ag NPs and ZnSe-Au NPs, allows the discussion of interaction mechanisms such as charge carrier transfer and Förster interaction. Finally, we assess an alternative method for the sensitization of wide band gap semiconductors to visible light by discussing the relationship between the carrier dynamics of TiO2 NPs and V-doped TiO2 NPs and their catalytic properties.

Fabrication of V-doped TiO2 nano-particles loaded multiwall carbon nanotube and investigation of optical and photocatalytic properties

In this work, V-doped TiO2 nano-particles loaded on the multiwall carbon nanotubes (MWCNTs) were prepared. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), BET surface area, photoluminescence (PL) spectroscopy, and UV–vis diffuse reflectance spectroscopy (DRS) techniques were utilized to characterization of the prepared samples. The photocatalytic activity of the prepared sample was evaluated through decolorization of reactive red 198 under visible light irradiations. The XRD patterns presented that the V-doped TiO2 loaded on the MWCNT contained just anatase phase. The surface area of the TiO2 increased from 48 m2 g−1 to 71 m2 g−1 through the construction of the nano-composite. The FE-SEM images of the samples detected that the V doped TiO2 particles were deposited homogeneously on the MWCNT surface whilst the average size of the particles was 25 nm. DRS illustrated that the absorption edge of the TiO2 shifted to the visible region during V doping and MWCNT loading. The obtained photocatalytic results indicated that during visible light irradiation (300 min), the reactive red 198 decolorized around 66% and 27% in the presence of the V-doped TiO2 loaded MWCNT and TiO2, respectively.

Oxidation state and structural studies of vanadium-doped titania particles for the visible light-driven photocatalytic activity

V-doped TiO2 nanoparticles (NPs) were synthesized by the sol–gel hydrolysis method using titanium butoxide (Ti(OBu)4) and vanadyl acetylacetonate (VO(acac)2) as the precursor and dopant, respectively. The effects of different V:Ti ratios on the crystal structure, bandgap energy, and photocatalytic activity were investigated. The photocatalytic activity of V-doped TiO2 NPs was evaluated by UV–vis absorption spectroscopy through the degradation of a methylene blue (MB) solution under visible light irradiation. The Raman spectra and X-ray diffraction patterns show that V was doped effectively, and oxygen vacancies and various defects or Ti3+ centers were formed. The results of energy dispersive X-ray analysis and X-ray photoelectron spectroscopy indicated the presence of V in the TiO2. The bandgap energy of 0.45% V-doped TiO2 NPs was determined to be 2.34 eV with a distinct red shift from 3.25 eV confirmed by diffuse reflectance spectroscopy. The photocatalytic activity of V-doped TiO2 NPs exhibited 2 times higher enhanced visible-light-induced photocatalytic performance compared to the pristine TiO2 NPs.

Synthesis and characterization of V-doped TiO2 nanoparticles through polyol method with enhanced photocatalytic activities

This work reports the synthesis of vanadium-doped titanuim dioxide nanoparticles using titanium chloride and ethylene glycol as precursor and solvent respectively. The properties of as-prepared samples were investigated by X-ray diffractometry, scaning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance, and thermal analysis. X-ray diffraction patterns indicate that the TiO2 nanoparticles obtained after calcination at 500 °C under air atmosphere has the anatase phase with a tetragonal structure and the crystallite sizes were in the range 16.83–12.27 nm. The transmission electron microscopy was used to detect the morphology of synthesized nanoparticles. The functional groups present in the samples were identified by FTIR study. From the optical studies, there is a blue shift in the absorption edge for our samples that can be attributed to the presence of V in the TiO2. For V doped TiO2 nanoparticles the optical band gap varies between 3.18 and 2.60 eV with the increase of V concentration. The TGA findings allow the thermal cycle determination of samples whereas DTA findings allow the phase transition temperature identification. Finally, the evaluation of the photocatalytic activity is carried out using methyl blue as model of chemical pollutants in UV irradiation conditions and followed satisfactory the pseudo first order according to the Langmuir–Hinshelwood model.

Photodegradation of spent wash, a sugar industry waste, using vanadium-doped TiO2 nanoparticles.

Waste from the sugar cane industry and alcohol distilleries is one of the sources of water pollution, and the degradation of this effluent is a very challenging task. Photocatalytic degradation can be an attractive alternative to conventional degradation processes. A vanadium-doped TiO2 (V-TiO2) photocatalyst for the degradation of spent wash and industrial dyes has been studied and reported here. V-doped TiO2 nanoparticles were prepared using a sol–gel method based on aqueous titanium peroxide with titanium isopropoxide as the Ti precursor and V2O5 as the V precursor. In order to observe the effect of the dopant on sol–gel behaviour, physicochemical and structural properties, the concentration of V was varied between 1.0% and 5% by weight. The crystallization temperature and time were optimized to obtain the required phase of V-TiO2. The physicochemical and structural characteristics of the V-doped TiO2 catalyst were determined using Brunauer–Emmett–Teller (BET), X-ray diffraction, FESEM, TEM, TG, FT-IR, Raman, PL and UV-visible spectroscopic techniques. UV-visible analysis showed a red shift in the absorption edge of TiO2 upon doping with V metal, which suggested an increase in the absorption of visible light due to a decrease in the effective band gap. The application potential of the V-TiO2 catalyst was studied via the degradation of sugar industry waste (spent wash) and Jakofix red dye (HE 8BN) under natural sunlight, as well as a standard artificial solar energy source (Xe lamp). The highest activity was observed for a 1% V-TiO2 photocatalyst for the degradation of spent wash and Jakofix red dye under natural sunlight. The degradation of coloured compounds in spent wash was monitored by gel permeation chromatography (GPC), which showed the degradation of high-molecular-weight compounds into low-molecular-weight fractions. The catalyst decomposed 90% of Jakofix red dye (HE 8BN) in 3.5 h and 65% of spent wash in 5 h under irradiation with natural sunlight, whereas Degussa P-25 TiO2 was only able to decompose 35% of the dye and 20% of spent wash under identical reaction conditions. A cycling stability test showed the high stability and reusability of the photocatalyst for degradation reactions, with a recovery of around 94–96%.

Element-specific channels for the photoexcitation of V-doped TiO2 nanoparticles

Element-specific channels for the photoexcitation of V-doped <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ti</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> nanoparticles

Co-precipitation synthesis of V-doped titania: influence of vanadium concentration on the structural and optical properties

V-doped TiO2 nanoparticles with different proportions were prepared by co-precipitation method. XRD patterns indicate that the TiO2 nanoparticles obtained after calcination at 500 °C in air has the anatase phase with a tetragonal structure and the crystallite sizes were in the range 11.4–9.5 nm, which are consistent with the results obtained from TEM images. The functional groups present in the samples were identified by FTIR study. From the optical studies, there is a blue shift in the absorption edge for our samples that can be attributed to the presence of V in the TiO2. For V doped TiO2 nanoparticles the optical band gap varies between 3.19 and 2.83 eV with the increase of V concentration. It was found that the doping V5+ ions have a significant influence on the optical properties. The room temperature photoluminescence (PL) spectra showed characteristic UV emission peaks of anatase at 529 nm and appropriate amount of V doping could slow the radiative recombination process of photogenerated electrons and holes in TiO2.

Synthesis of Sc and V-doped TiO2 nanoparticles and photodegradation of rhodamine-B

Anatase TiO2 nanoparticles doped with Sc and V were synthesized and their photocatalytic activities were evaluated through the photodegradation of rhodamine-B under UV irradiation. TiO2 shows the highest photocatalytic activity and Sc doped TiO2 and V doped TiO2 show lower photocatalytic activity than TiO2. In contrast, Sc and V codoped TiO2 shows no any photocatalytic activity. The reasons for the decrease in photocatalytic activity is due to the presence of surficial Sc2O3 islands covering the reactive sites for Sc doped TiO2 and the increased e−/h+ pair recombination resulted from the high level substitutional V(IV) ions for V doped TiO2, respectively.

Fabrication of V-Doped TiO2 Nanoparticles and Photocatalytic Studies under Visible Light

The V-doped TiO2 nanoparticles were successfully prepared by sol-gel method and characterized by X-ray diffraction (XRD), UV-vis spectroscopy and photoluminescence (PL) spectroscopy respectively. It is found that doping V can shift the absorption edge to the visible light region and decrease the recombination of photo-induced electron-hole pairs. Then the photo-absorption and photocatalytic activity were greatly improved. The optimal doping concentration is 0.5% due to synergetic effect of the recombination of electron-hole pairs and adsorption of dyes molecules at the surface of samples.

Physical properties of V-doped TiO2 nanoparticles synthesized by sonochemical-assisted process

Abstract V-doped TiO 2 nanoparticles were synthesized by sonochemical process using titanium isopropoxide as a titanium source, vanadyl acetylacetonate as a dopant source. Sonication was conducted using sonic horn operated at 20 kHz for 20 min until the completely precipitated product was reached. The as-synthesized precipitates with various vanadium dopant (1–5 mol %) were calcined at 500–1000 °C for 4 h. The relevant physical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). The anatase phase TiO 2 nanoparticles can be synthesized by sonochemical process. Post calcinations process results in the anatase-to-rutile phase transformation and the enhancement in crystallinity with increasing temperature. The results also indicate good incorporation of V ions in TiO 2 lattices and significant effect of V dopant on alternation of interplanar spacing of TiO 2 .

Adsorption and solar light activity of transition-metal doped TiO2 nanoparticles as semiconductor photocatalyst

There is an eminent interest to improve the photoactivity of TiO2 nanostructures via doping with mid-band gap donors or acceptors to achieve a high solar absorption. In the present work, Cr- and V-doped TiO2 nanoparticles were prepared via a facile chemical vapor synthesis method. The effect of the transition metals (TM) on the solar light activity of the semiconductor nanoparticles as photocatalyst was examined by degradation of methylene blue and acid red 27. Induced coupled plasma and X-ray photoelectron spectroscopy analyses indicated high efficiency of the doping process in the hot wall reactor without surface covering of the TiO2 nanoparticles by the dopants. Diffuse reflectance spectroscopy also revealed a red shift of the absorption edge of the TiO2 nanoparticles with increasing dopant concentration. Analysis of the photoactivity of the synthesized nanoparticles under sun light showed an increase in the primary absorption of dye molecules on the surface of Cr- and V-doped TiO2 nanoparticles whereas the degradation rate was found to depend on the type and concentration of the dopants. A high photoactivity is obtained at 0.2 at% V concentration. The mechanism of photoactivity is discussed based on the effect of TM on the absorption edge of the semiconductor.

Low temperature fabrication of V-doped TiO 2 nanoparticles, structure and photocatalytic studies

V-doped TiO 2nanoparticles were synthesized at low temperature and characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, and photoluminescence (PL) spectroscopy, respectively. It is found the nanoparticle shape changed from needle, to short stick and then to cubic with the increase of doped V concentration, which was also accompanied by the improvement of crystallinity. The specific surface area ( S B E T ) decreased with increasing V content. It is confirmed that V ions can be doped in TiO 2 by substituting Ti 4+ ions, which suppressed the CB → VB and surface recombination of photoinduced electrons and holes, and a relation was found between the PL spectra and the UV photocatalytic activity. There was an optimum V content for the V-doped TiO 2 to present the best UV-light induced photoactivity, but they were visible-inactive. At last, the effect of the doping V as trapping centers on photocatalysis was investigated in detail, and used to explain the difference between the photocatalysis under the illumination of UV light and visible light.

Characterization and photocatalytic activity of vanadium-doped titanium dioxide nanocatalysts

The vanadium (V)-doped mesoporous titanium dioxide (TiO(2)) nanoparticles with V/Ti ratios from 0-2 wt% were prepared using sol-gel method in the presence of triblock polymers, Pluronic F127. SEM images showed that the V-doped TiO(2) nanoparticles were porous structures. The surface areas and pore sizes were in the range 85-107 m(2)/g and 12-14 nm, respectively. From XRPD, the V-doped mesoporous TiO(2) after calcination at 500 degrees C was mainly anatase phase, and the crystallite sizes were in the range 14-16 nm. TEM images showed that vanadia was doped both on the surface and in the lattice of anatase TiO(2). A slight red-shift in wavelength absorption was observed when V/Ti ratio increased from 0 to 2 wt%. Addition of vanadium ion slightly decreased the photocatalytic activity of TiO(2) toward the decolorization of MB under the illumination of UV light at 305 nm. However, a 1.6-1.8 times increase in rate constants for MB photodegradation was observed when 0.5-1.0 wt% V-doped TiO(2) was illumined by solar simulator at AM 1.5. These results demonstrated that the doping of low concentrations of V ion into mesoporous TiO(2) enhance the photocatalytic activity of mesoporous TiO(2) towards photodecomposition of azo dye in the visible range.