Impact of Rutile Fraction on TiO2 Visible-Light Absorption and Visible-Light-Induced Photocatalytic Activity

2018 ◽  
Author(s):  
David Maria Tobaldi ◽  
Luc Lajaunie ◽  
ana caetano ◽  
nejc rozman ◽  
Maria Paula Seabra ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Solid Phase ◽  
Diffraction Method ◽  
Band Alignment ◽  
Quantitative Phase Analysis ◽  
Transmission Microscopy ◽  
Visible Light Absorption ◽  
X Ray

<div>Titanium dioxide is by far the most utilised semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile−anatase mixture would improve its visible-light absorption.</div><div>In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2. </div><div>The structural characterisation was done via advanced X-ray diffraction method, namely the Rietveld-RIR method, to attain a full quantitative phase analysis of the specimens. The microstructure was also investigated via an advanced X-ray method, the whole powder pattern modelling. These methods were validated combining advanced aberration-corrected scanning transmission microscopy and high-resolution electron energy-loss spectroscopy. The photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.</div><div>Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light?</div><div>We tried to give a reply to that question.</div><div>Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-induced catalytic activity (i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects). That is: not photocatalysis <i>sensu-strictu</i>.</div><div>On the other hand, the gas-solid phase results showed that a higher amount of the rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for an actual photocatalytic oxidation of isopropanol.</div>

Impact of Rutile Fraction on TiO2 Visible-Light Absorption and Visible-Light-Induced Photocatalytic Activity

2018 ◽  
Author(s):  
David Maria Tobaldi ◽  
Luc Lajaunie ◽  
ana caetano ◽  
nejc rozman ◽  
Maria Paula Seabra ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Solid Phase ◽  
Diffraction Method ◽  
Band Alignment ◽  
Quantitative Phase Analysis ◽  
Transmission Microscopy ◽  
Visible Light Absorption ◽  
X Ray

<div>Titanium dioxide is by far the most utilised semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile−anatase mixture would improve its visible-light absorption.</div><div>In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2. </div><div>The structural characterisation was done via advanced X-ray diffraction method, namely the Rietveld-RIR method, to attain a full quantitative phase analysis of the specimens. The microstructure was also investigated via an advanced X-ray method, the whole powder pattern modelling. These methods were validated combining advanced aberration-corrected scanning transmission microscopy and high-resolution electron energy-loss spectroscopy. The photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.</div><div>Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light?</div><div>We tried to give a reply to that question.</div><div>Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-induced catalytic activity (i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects). That is: not photocatalysis <i>sensu-strictu</i>.</div><div>On the other hand, the gas-solid phase results showed that a higher amount of the rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for an actual photocatalytic oxidation of isopropanol.</div>

scholarly journals Nickel and sulfur codoped TiO2 nanoparticles for efficient visible light photocatalytic activity

2021 ◽  
Author(s):  
Mehala Kunnamareddy ◽  
Ranjith Rajendran ◽  
Megala Sivagnanam ◽  
Ramesh Rajendran ◽  
Barathi Diravidamani
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Fourier Transforms ◽  
Phase Particle ◽  
Energy Dispersive Spectrometer ◽  
Sol Gel ◽  
Bandgap Energy ◽  
Visible Light Absorption

AbstractIn this work, Nickel (Ni) and sulfur (S) codoped TiO2 nanoparticles were prepared by a sol-gel technique. The as-prepared catalyst was characterized using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), FT-Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (DRS) for investigating crystal structure, crystal phase, particle size and bandgap energy of these samples. The photocatalytic performances of all the prepared catalysts have been investigated for the degradation of methylene blue (MB) under visible light irradiation. It was noticed that Ni-S codoped TiO2(Ni-S/TiO2) nanoparticles exhibited much higher photocatalytic activity compared with pure, Ni and S doped TiO2 due to higher visible light absorption and probable decrease in the recombination of photo-generated charges. It was decided that the great visible light absorption was created for codoped TiO2 by the formation of impurity energy states near both the edges of the collection, which works as trapping sites for both the photogenerated charges to decrease the recombination process.

Visible Light Absorption Characteristics of M-Nitrogen (M= Mn, Fe, Co, Ni, Cu) Co-Doped Monodisperse TiO2 Microparticles

2015 ◽  
Vol 1806 ◽  
pp. 19-24 ◽  
Author(s):  
John E. Mathis
Keyword(s):  
Photocatalytic Activity ◽  
Transition Metals ◽  
Visible Light ◽  
Light Absorption ◽  
Sol Gel ◽  
Percent Level ◽  
Wide Distribution ◽  
Electromagnetic Spectrum ◽  
Visible Light Absorption ◽  
Co Doping

ABSTRACTThere is great interest in improving TiO2’s photocatalytic activity in the visible portion of electromagnetic spectrum. Recent work has shown that co-doping mesoporous TiO2 microparticles with a transition metal and nitrogen, hereby designated as (M,N) TiO2, significantly increases its visible light absorption. However, the hydrothermal method used to produce the microparticles creates a wide distribution in the size of the microparticles, which could affect the absorption properties. Recently, it has become possible to produce monodisperse, mesoporous TiO2 microparticles with engineered sizes using a hybrid sol-gel/hydrothermal technique. Further, it has also been shown that the size of monodisperse TiO2 microparticles affects the the photocatalytic activity.This study investigated whether using mondodisperse (M,N) TiO2 microparticles would further increase visible-light absorption for (M,N)TiO2. The first-row transition metals chosen for this study - Mn, Fe, Co, Ni, and Cu – have been characterized in the earlier (M,N) TiO2 UV-vis study, which was used as a baseline. The doping levels of the transition metals samples were set at the 2.5 percent level previously shown to be optimum for photocatalytic activity.

scholarly journals Improving the photocatalytic activity of nitrogen-doped surface defect TiO2-x nanobelts for degradation of organic pollutants

2020 ◽  
pp. 174751982093867
Author(s):  
Zhen Zhang ◽  
Shao-dong Qin ◽  
Jing-yun Chen ◽  
Jing Li ◽  
Ai-hua Xing
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Organic Pollutants ◽  
Rhodamine B ◽  
Light Absorption ◽  
Surface Defect ◽  
Separation Efficiency ◽  
Visible Light Absorption ◽  
Nitrogen Doped ◽  
N Doping

The synthesis of surface defect TiO2-x nanobelts with excellent visible light absorption is important to reduce costs, increase stability, and improve photocatalytic activity. In this work, we report that nitrogen-doped surface defect TiO2-x nanobelts are synthesized by annealing pristine TiO2 nanobelts in Ar/H2 (95%/5%) atmosphere followed by subsequent heat treatment in NH3 at various temperatures. The aim is to study the effect of the extent of the N-doping amount in the lattice of TiO2-x nanobelts on light absorption and photocatalytic activity. Considering the increase in organic pollutants in wastewater, the photocatalytic activity is measured by degrading rhodamine B (RhB) dye in water. The results demonstrate that the calcination temperature affects the doping level of N, and the b-TiO2-N550 sample exhibits higher photocatalytic performance than that of other samples under visible-light irradiation for the degradation of rhodamine B, which is up to 96.11%. The enhancement is ascribed to the synergistic effect of N-doping and self-doping oxygen vacancy (which extend the visible light absorption) and the separation efficiency of photogenerated carriers, which improves the photocatalytic activity.

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

RSC Advances ◽  
2015 ◽  
Vol 5 (35) ◽  
pp. 27690-27698 ◽  
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.

The Photocatalytic Properties of Fe3+ and N Co-Doped TiO2 Micro/Nanofiber Film for Dye Waste Water Decomposition

2011 ◽  
Vol 356-360 ◽  
pp. 853-856 ◽  
Author(s):  
Qiao Zhen Yu ◽  
Xiang Jun Jin ◽  
Shao Yang Li ◽  
Lei Wang ◽  
Kun Long Liang
Keyword(s):  
Waste Water ◽  
Visible Light ◽  
Light Absorption ◽  
Oxygen Demand ◽  
Photocatalytic Efficiency ◽  
Energy Dispersion Spectroscopy ◽  
Visible Light Absorption ◽  
X Ray ◽  
Nano Fiber ◽  
Co Doped

To obtain a TiO2photocatalyst with high photocatalytic efficiency under visible irradiation and good reusability, the Fe3+and N co-doped TiO2micro/nano fiber films were fabricated by electrospinning and calcinations. The morphologies and structures of the resulting samples were analyzed by scanning electron microscopy (SEM), x-ray diffraction and x-ray energy dispersion spectroscopy (EDS). The absorbance and chemical oxygen demand (COD) were characterized respectively by UV–visible spectrophotometer and COD Rapid Tester. The results show that the Fe3+and N co-doped TiO2micro/nano fiber had a multi-porous structure with an average diameter of about 45 to 506 nm. The crystalinity degrees, visible light absorption of these films were affected by the dosage of Fe3+and N co-doping (DFN). Moreover, these films exhibited high photocatalytic activity for the degradation of dye waste water under sunlight and it was related to DFN. As DFN was 0.5 %, it has highest crystalinity degree, largest visible light absorption and highest photocatalytic efficiency on dye waste water. The decolor rate of the dye waste water was as high as 67.6 % and its COD decreased from 2800±200 to 236.40 ± 15.61, when the photocatalytic time was only 3 h.

The effective removal of Cr(vi) ions by carbon dot–silica hybrids driven by visible light

RSC Advances ◽  
2016 ◽  
Vol 6 (72) ◽  
pp. 68530-68537 ◽  
Author(s):  
Yun Liu ◽  
Yu-jie Ma ◽  
Chun-yan Liu ◽  
Zhi-ying Zhang ◽  
Wen-dong Yang ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Adsorption Capacity ◽  
Light Absorption ◽  
Visible Light Absorption ◽  
Carbon Dot ◽  
Effective Removal ◽  
Silica Hybrids ◽  
Silica Hybrid

A carbon dot–silica hybrid with a high dosage of CDs demonstrated significant visible light absorption, a large Cr(vi) adsorption capacity and good photocatalytic activity for the reduction of Cr(vi) in visible light.

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

2011 ◽  
Vol 284-286 ◽  
pp. 734-737 ◽  
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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