scholarly journals Activation Treatments and SiO2/Pd Modification of Sol–Gel TiO2 Photocatalysts for Enhanced Photoactivity under UV Radiation

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1184
Author(s):  
Julien Mahy ◽  
Valériane Sotrez ◽  
Ludivine Tasseroul ◽  
Sophie Hermans ◽  
Stéphanie Lambert
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Uv Radiation ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Visible Range ◽  
Crystallographic Structure ◽  
Tio2 Sample ◽  
Tio2 Photocatalysts

The objective of this work is to improve the efficiency of TiO2 photocatalysts by activation treatments and by modification with palladium nanoparticles and doping with SiO2. The influence of the additive loading was explored, and two activation treatments were performed: UV exposition and H2 reduction. TiO2/SiO2/Pd photocatalysts were synthesized by an original cogelation method: a modified silicon alkoxide, i.e., [3-(2-aminoethyl)aminopropyl]trimethoxysilane (EDAS), was used to complex the palladium ions, thanks to the ethylenediamine group, while the alkoxide groups reacted with TiO2 precursors. Pure TiO2 was also synthesized by the sol–gel process for comparison. X-ray diffraction evidenced that the crystallographic structure of TiO2 was anatase and that Pd was present, either in its oxidized form after calcination, or in its reduced form after reduction. The specific surface area of the samples varied from 5 to 145 m2 g-1. Transmission electron microscopy allowed us to observe the homogeneous dispersion and nanometric size of Pd particles in the reduced samples. The width of the band gap for pure TiO2 sample, measured by UV/Visible diffuse reflectance spectroscopy at approximately 3.2 eV, corresponded to that of anatase. The band gap for the TiO2/SiO2/Pd composite samples could not be calculated, due to their high absorption in visible range. The photocatalytic activity of the various catalysts was evaluated by the degradation of a methylene blue solution under UV radiation. The results showed that the photocatalytic activity of the catalysts was inversely proportional to the content of silica present in the matrix. A small amount of silica improved the photocatalytic activity, as compared to the pure TiO2 sample. By contrast, a high amount of silica delayed the crystallization of TiO2 in its anatase form. The activation treatment under UV had little influence on photocatalytic efficiency. The introduction of Pd species increased the photocatalytic activity of the samples because it allowed for a decrease in the rate of electron–hole recombinations in TiO2. The reduction treatment improved the activity of photocatalysts, whatever the palladium content, thanks to the reduction of Ti4+ into Ti3+, and the formation of defects in the crystallographic structure of anatase.

scholarly journals Enhanced Photocatalytic Activity of CuWO4 Doped TiO2 Photocatalyst Towards Carbamazepine Removal under UV Irradiation

Separations ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 25
Author(s):  
Chukwuka Bethel Anucha ◽  
Ilknur Altin ◽  
Emin Bacaksız ◽  
Tayfur Kucukomeroglu ◽  
Masho Hilawie Belay ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Component Part ◽  
Energy Yield ◽  
Mechanical Agitation ◽  
X Ray

Abatement of contaminants of emerging concerns (CECs) in water sources has been widely studied employing TiO2 based heterogeneous photocatalysis. However, low quantum energy yield among other limitations of titania has led to its modification with other semiconductor materials for improved photocatalytic activity. In this work, a 0.05 wt.% CuWO4 over TiO2 was prepared as a powder composite. Each component part synthesized via the sol-gel method for TiO2, and CuWO4 by co-precipitation assisted hydrothermal method from precursor salts, underwent gentle mechanical agitation. Homogenization of the nanopowder precursors was performed by zirconia ball milling for 2 h. The final material was obtained after annealing at 500 °C for 3.5 h. Structural and morphological characterization of the synthesized material has been achieved employing X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) N2 adsorption–desorption analysis, Scanning electron microscopy-coupled Energy dispersive X-ray spectroscopy (SEM-EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-vis DRS) for optical characterization. The 0.05 wt.% CuWO4-TiO2 catalyst was investigated for its photocatalytic activity over carbamazepine (CBZ), achieving a degradation of almost 100% after 2 h irradiation. A comparison with pure TiO2 prepared under those same conditions was made. The effect of pH, chemical scavengers, H2O2 as well as contaminant ion effects (anions, cations), and humic acid (HA) was investigated, and their related influences on the photocatalyst efficiency towards CBZ degradation highlighted accordingly.

Europium Doped Titania Nanocomposites with Enhanced Photocatalytic Activity towards the Degradation of Partially Hydrolysis Polyacrylamide

2011 ◽  
Vol 391-392 ◽  
pp. 219-224
Author(s):  
Jin Huan Li ◽  
Hong Bo Fang ◽  
Wei Wang ◽  
Gui Fan Liu ◽  
Shao Dong Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Oil Recovery ◽  
Inductively Coupled Plasma ◽  
Diffuse Reflectance Spectroscopy ◽  
Uv Light ◽  
Anatase Phase ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Surface Shape ◽  
Titanium Tetraisopropoxide

Nanocrystals with different Eu3+ doping levels (%) were prepared by sol-gel and hydrothermal synthetic method using titanium tetraisopropoxide (TTIP) as titanium source. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The crystallite sizes, crystal form, surface shape, composition and optical property of catalysts were characterized by X-ray diffraction patterns, UV-Vis diffuse reflectance spectroscopy, XPS and inductively coupled plasma atomic emission spectroscopy. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu3+ composites, and the reasons were explained.

The Influence of Cr Doped TiO2 on the Optical Property and Photocatalytic Activity under Sunlight Irradiation

2016 ◽  
Vol 13 (1) ◽  
pp. 99
Author(s):  
Siti Zulaikha Suhaili ◽  
Muhamad Kamil Yaakob ◽  
Siti Irma Yuana Saaid ◽  
Umi Sarah Jais
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Diffraction Method ◽  
Band Gap Energy ◽  
Pure Tio2 ◽  
Photocatalytic Efficiency ◽  
Sunlight Irradiation ◽  
Doped Tio2 ◽  
Gap Energy

Pure TiO2 and Cr doped TiO2 (0.1-1.0wt% Cr) nanoparticles were synthesized via sol gel method. This study focuses on narrowing the TiO2 band gap energies in order to enhance the photocatalytic efficiency under visible light. The synthesized samples were characterized by X-Ray diffraction method (XRD), field emmision (FESEM) and also UV-Vis diffuse reflectance spectroscopy (DRS).The photocatalytic activity under sunlight irradiation was demonstrated by photocatalytic decomposition of methylene blue in water using UV/Vis spectrophotometer. The XRD analysis of pure TiO2 and doped TiO2 calcined at 500oC showed a mixture of anatase and rutile phases with decreasing crystallites size from 13.3nm to 11.6nm as the concentration of Cr was increased. The anatase-rutile phase transformation increased from 28.8% to 57.4%. An indication shows that at 0.75wt%, Cr the anatase and rutile phases have equal composition percentage. This study demonstrated that band gap energy of TiO2 was reduced with Cr doping which could enhance the photocatalytic efficiency. Sample containing 1.0wt% exhibit the lowest optical band gap energy at 2.86 eV. The optimum chromium doping concentration was found to be at 0.1 wt% Cr corresponding to band gap energy of 2.87 eV and degradation rate of 84%. 

The Influence of Cr Doped TiO2 on the Optical Property and Photocatalytic Activity under Sunlight Irradiation

2016 ◽  
Vol 13 (1) ◽  
pp. 99
Author(s):  
Siti Zulaikha Suhaili ◽  
Muhamad Kamil Yaakob ◽  
Siti Irma Yuana Sheikh Mohd Saaid ◽  
Umi Sarah Jais
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Diffraction Method ◽  
Band Gap Energy ◽  
Pure Tio2 ◽  
Photocatalytic Efficiency ◽  
Sunlight Irradiation ◽  
Doped Tio2 ◽  
Gap Energy

Pure TiO2 and Cr doped TiO2 (0.1-1.0wt% Cr) nanoparticles were synthesized via sol gel method. This study focuses on narrowing the TiO2 band gap energies in order to enhance the photocatalytic efficiency under visible light. The synthesized samples were characterized by X-Ray diffraction method (XRD), field emmision (FESEM) and also UV-Vis diffuse reflectance spectroscopy (DRS).The photocatalytic activity under sunlight irradiation was demonstrated by photocatalytic decomposition of methylene blue in water using UV/Vis spectrophotometer. The XRD analysis of pure TiO2 and doped TiO2 calcined at 500oC showed a mixture of anatase and rutile phases with decreasing crystallites size from 13.3nm to 11.6nm as the concentration of Cr was increased. The anatase-rutile phase transformation increased from 28.8% to 57.4%. An indication shows that at 0.75wt%, Cr the anatase and rutile phases have equal composition percentage. This study demonstrated that band gap energy of TiO2 was reduced with Cr doping which could enhance the photocatalytic efficiency. Sample containing 1.0wt% exhibit the lowest optical band gap energy at 2.86 eV. The optimum chromium doping concentration was found to be at 0.1 wt% Cr corresponding to band gap energy of 2.87 eV and degradation rate of 84%.

Preparation and Photocatalytic Performances of F-Doped TiO2

2014 ◽  
Vol 936 ◽  
pp. 814-818 ◽  
Author(s):  
Xian Zhen Diao ◽  
Xi Li Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Doping Amount ◽  
Tio2 Photocatalysts ◽  
Infrared Spectrometer ◽  
Blue Solution ◽  
Lamp Illumination

Butyl acetate titanate as precursors, no water ethanol as solvent, pure TiO2 and different doping ratio of F/TiO2 photocatalysts were prepared through sol-gel method; And F doping amount on photocatalytic activity of TiO2 influences were analysed systematically through uv-vis spectrophotometer, infrared spectrometer, etc. Experimental results show that photocatalytic activity of TiO2 is better when the mole ratio of F is between 10% and 20%; When F doping amount is 20%, catalyst amount is 25g, the photocatalytic degradation rate of F/TiO2 can reach 85.74% in10%wt methylene blue solution under 250W high-voltage mercury lamp illumination after 2 hours and the area of illumination 6.94×10-3m2. In the same way, the photocatalytic degradation rate of pure TiO2 is just 35.39 %. It proves that F/TiO2 catalyst of doping amount 20% presents the best photocatalytic activity.

scholarly journals Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3874 ◽  
Author(s):  
Abderrahim El Mragui ◽  
Yuliya Logvina ◽  
Luís Pinto da Silva ◽  
Omar Zegaoui ◽  
Joaquim C.G. Esteves da Silva
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Anatase Phase ◽  
Aqueous Suspension ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Doped Tio2 ◽  
Doped Titania ◽  
Co Doped

Pure TiO2 and Fe- and Co-doped TiO2 nanoparticles (NPs) as photocatalysts were synthesized using wet chemical methods (sol-gel + precipitation). Their crystalline structure and optical properties were analyzed using X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible light (UV-Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the synthesized nanoparticles was evaluated through degradation of carbamazepine (CBZ) under UV-A and visible-light irradiations. The XRD and Raman analyses revealed that all synthesized nanomaterials showed only the anatase phase. The DRS results showed that the absorption edge was blue-shifted for Fe-doped TiO2 NPs. The decrease in charge recombination was evidenced from the PL investigation for both Co-doped and Fe-doped TiO2 nanomaterials. An enhancement in photocatalytic degradation of carbamazepine in aqueous suspension under both UV-A light and visible-light irradiations was observed for Fe-doped Titania NPs by comparison with pure TiO2. These results suggest that the doping cations could suppress the electron/hole recombination. Therefore, the photocatalytic activity of TiO2-based nanomaterials was enhanced.

Preparation and Photocatalytic Activity of Fe-Ce-N Tri-Doped TiO2 Catalysts

2013 ◽  
Vol 750-752 ◽  
pp. 1276-1282
Author(s):  
Yao Yao Wang ◽  
Hong Xie ◽  
Wei Zhang ◽  
Yu Bin Tang ◽  
Fang Yan Chen
Keyword(s):  
Photocatalytic Activity ◽  
Diffuse Reflectance Spectroscopy ◽  
Uv Light ◽  
Anatase Phase ◽  
Sol Gel ◽  
Synergetic Effect ◽  
Tetrabutyl Titanate ◽  
Visible Range ◽  
Doping Amount ◽  
Optimal Doping

Fe-Ce-N tri-doped TiO2 photocatalyst was prepared by sol-gel method using tetrabutyl titanate as precursor. The optimal doping amount and calcinations temperature were determined. The prepared catalyst was characterized by X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectroscopy, and the photocatalytic activity was evaluated by means of the degradation for methyl orange (MO) under UV light and daylight irradiation. The results indicated that the optimal doping amount was 1.0% N, 0.25% Fe and 0.05% Ce, and the appropriate calcination temperature was 400°C. XRD analysis showed that TiO2 existed in anatase phase completely. UV-Vis adsorption spectrum showed that Fe-Ce-N tri-doping resulted in a intense adsorption in the near UV and visible-light region and a red shift in the adsorption edge from UV range to visible range of 400-500nm. The photocatalytic activity of Fe-Ce-N tri-doped TiO2 under UV and daylight irradiation was very higher than that of bi-doped Fe-Ce-TiO2, Fe-N-TiO2, Ce-N-TiO2 and undoped TiO2. The significantly higher activity of Fe-Ce-N tri-doped TiO2 may be due to the synergetic effect of Fe, Ce and N in the tri-coped TiO2.

Sol-Gel Synthesis of Na2Ta4O11 Nanocrystals Showing High Efficient Photocatalytic Performance

2014 ◽  
Vol 1058 ◽  
pp. 35-39 ◽  
Author(s):  
Yi Guo Su ◽  
Xu Yang ◽  
Ting Ting Wang ◽  
Bao Ling Zhu ◽  
Xiao Jing Wang
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Active Species ◽  
Gap Energy ◽  
High Efficient ◽  
Sol Gel Synthesis

Semiconductors showing high efficient photocatalytic activity have attracted great interest, because they provide a potential solution to many environmental pollution problems that humankind is currently facing. This work reports on the sol-gel synthesis of Na2Ta4O11 nanocrystals and its photocatalytic performance toward Red G. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and the Barrett–Emmett–Teller technique. By modulating the synthetic condition, the sol-gel reaction yielded pure Na2Ta4O11 nanocrystals with diameter of ~32 nm from the peak broadening of (006) plane using Scherrer formula. It is found that the as-prepared Na2Ta4O11 nanocrystals showed a band gap energy of 3.63 eV, which is much smaller than that of Na2Ta4O11 prepared by flux approach. The relative narrowed band gap energy of Na2Ta4O11 nanocrystals may predict superior photocatalytic activity. By careful photocatalytic test, it is found that Na2Ta4O11 nanocrystals showed excellent photocatalytic activity toward Red G. The photocatalytic degradation efficiency was estimated to be 94.0% within a time intervals of 40 minutes. Controlled experiment by adding active species scavengers gave evidence that the degradation of Red G is dominated by the oxidation reaction of the generated O2-∙ active species taking place on the surface of the photocatalyst.

scholarly journals ­Improved Luminescence and Photocatalytic Proprieties of Sm3+-doped ZnO Nanoparticles Via Modified Sol-Gel Route: An Unified Experimental and DFT+U Approach

2021 ◽  
Author(s):  
Sikder Ashikuzzaman Ayon ◽  
Sajjad Hasan ◽  
Md Muktadir Billah ◽  
Sadiq Shahriyar Nishat ◽  
Alamgir Kabir
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Structural Properties ◽  
Morphological Evolution ◽  
Sol Gel ◽  
Photogenerated Electron ◽  
Luminescence Spectra ◽  
Visible Range ◽  
Electron Hole ◽  
Mole Percent

Abstract In the current study, a modified sol-gel route was followed to produce undoped and Sm3+ doped (1, 3 and 5 mol %) nanoparticles. The study of opto-structural properties of Sm3+ doped NPs was carried out both experimentally and theoretically. Complete dissolution of Sm3+ ions into the ZnO lattice was obvious from XRD analysis. Morphological evolution with doping was studied using FESEM and TEM. XPS was carried out to confirm the presence of Sm3+ on the surface of the doped NPs. Increasing dopant quantity resulted in a red shift of the NPs along with a reduction in band gap with increasing absorption in the visible range, and a minimum of 3.18 eV of optical band gap for Zn0.97Sm0.03O was found. Photoluminescence spectroscopy revealed a drop in the recombination rate of electron-hole with increasing doping till 3 mole %, followed by an increase for Zn0.95Sm0.05O. Photogenerated electron-hole pair recombination was revealed by the orange band in the luminescence spectra. Theoretical analysis was also carried out with density function theory (DFT). This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully. Later, photocatalytic activity for the optimum composition i.e., 3 mole percent, was assessed experimentally.

Enhanced visible-active photocatalytic behaviors observed in Mn-doped BiFeO3

2018 ◽  
Vol 32 (17) ◽  
pp. 1850185 ◽  
Author(s):  
Yun-Hui Si ◽  
Yu Xia ◽  
Ya-Yun Li ◽  
Shao-Ke Shang ◽  
Xin-Bo Xiong ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Mn Doped ◽  
Hole Recombination ◽  
Narrow Band Gap Semiconductors

A series of BiFeO3 and BiFe[Formula: see text]Mn[Formula: see text]O3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by a hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy, and their photocatalytic activity was studied by photocatalytic degradation of methylene blue in aqueous solution under visible light irradiation. The band gap of BiFeO3 was significantly decreased from 2.26 eV to 1.90 eV with the doping of Mn. Furthermore, the 6% Mn-doped BiFeO3 photocatalyst exhibited the best activity with a degradation rate of 94% after irradiation for 100 min. The enhanced photocatalytic activity with Mn doping could be attributed to the enhanced optical absorption, increment of surface reactive sites and reduction of electron–hole recombination. Our results may be conducive to design more efficient photocatalysts responsive to visible light among narrow band gap semiconductors.

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