scholarly journals Synthesis of Heterostructure of ZnO@MOF-46(Zn) to Improve the Photocatalytic Performance in Methylene Blue Degradation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1379
Author(s):  
Jiraporn Buasakun ◽  
Phakinee Srilaoong ◽  
Ramida Rattanakam ◽  
Tanwawan Duangthongyou
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Band Gap Energy ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Methylene Blue Degradation ◽  
Gap Energy ◽  
Hole Recombination

The heterostructure of ZnO and MOF-46(Zn) was synthesized to improve the photocatalytic performance of ZnO and prove the synergistic theory that presented the coexistence of ZnO and MOF-46(Zn), providing better efficiency than pure ZnO. The heterostructure material was synthesized by using prepared ZnO as a Zn2+ source, which was reacted with 2-aminoterephthalic acid (2-ATP) as a ligand to cover the surface of ZnO with MOF-46(Zn). The ZnO reactant materials were modified by pyrolysis of various morphologies of IRMOF-3 (Zn-MOF) prepared by using CTAB as a morphology controller. The octahedral ZnO obtained at 150 mg of CTAB shows better efficiency for photodegradation, with 85.79% within 3 h and a band gap energy of 3.11 eV. It acts as a starting material for synthesis of ZnO@MOF-46(Zn). The ZnO/MOF-46(Zn) composite was further used as a photocatalyst material in the dye (methylene blue: MB) degradation process, and the performance was compared with that of pure prepared ZnO. The results show that the photocatalytic efficiency with 61.20% in the MB degradation of the heterostructure is higher than that of pure ZnO within 60 min (90.09% within 180 min). The reason for this result may be that the coexistence of ZnO and MOF-46(Zn) can absorb a larger range of energy and reduce the possibility of the electron–hole recombination process.

Tuning the electronic and structural properties of WO3 nanocrystals by varying transition metal tungstate precursors

RSC Advances ◽  
2014 ◽  
Vol 4 (107) ◽  
pp. 62423-62429 ◽  
Author(s):  
Sara Rahimnejad ◽  
Jing Hui He ◽  
Wei Chen ◽  
Kai Wu ◽  
Guo Qin Xu
Keyword(s):  
Methylene Blue ◽  
Transition Metal ◽  
Oxygen Vacancy ◽  
Band Gap ◽  
Azo Dye ◽  
Electron Hole ◽  
Recombination Time ◽  
Metal Tungstate ◽  
Electronic And Structural Properties ◽  
Hole Recombination

WO3 nanoplates derived from NiWO4 were found to have the highest concentration of oxygen vacancy, narrowest band gap, longest electron–hole recombination time, and in turn the highest rate of photodegradation of azo dye methylene blue.

Synthesis,Surface Morphology, Optical Properties and Photocatalyst Activities of TiO2/ZnO/Fe2O3 Nanocomposites.

2020 ◽  
Author(s):  
Juliya Acha Parambil ◽  
Abdul Mujeeb V.M ◽  
S. Zh. Karazhanov ◽  
Jayaram Peediyekkal
Keyword(s):  
Methylene Blue ◽  
Optical Properties ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Photoluminescence Intensity ◽  
Methylene Blue Degradation ◽  
Gap Energy ◽  
First Order ◽  
First Order Kinetics ◽  
Transition Surface

Abstract The photocatalytic degradation of methylene blue in aqueous solutions is enhanced significantly by formulating multiphase TiO2/ZnO/Fe2O3 nanocomposites. The photocatalytic activity of unary TiO2, binary TiO2/ZnO, and ternary TiO2/ZnO/Fe2O3 compounds are compared and reported. Using TiO2/ZnO/Fe2O3, methylene blue degradation became rapid and the reaction followed first-order kinetics. The consequences of the phase transition, surface features, and optical properties are compared and elucidated. The reduced photoluminescence intensity and decreased optical band gap energy in tertiary compounds impose higher degradation of methylene blue under irradiation.

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.

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 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.

Evidence for Strong Trapping by Ionized Donors of Free Excitions in Excited States for High Purity GaAs and AlGaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
S. Zemon ◽  
G. Lambert
Keyword(s):  
Band Gap ◽  
Excited States ◽  
High Purity ◽  
Free Exciton ◽  
Band Gap Energy ◽  
Excitation Energies ◽  
Electron Hole ◽  
Gap Energy

AbstractStriking increases in the intensity of donor-related, photoluminescence transitions are observed in undoped (1014-1015 cm-3) GaAs for excitation energies (Ee) in the vicinity of the band-gap energy (Eg). The enhancement has maxima at Ee consistent with excitation of the n=2 and 3 states of the free exciton (Xn=2,3) and appears to be correlated to the concentration of ionized donors, suggesting that the effects are related to capture of electron-hole pairs by ionized donors through trapping of Xn=2,3. The enhancement decreases monotonically as Ee increases to values as much as 12 meV above Eg.

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%.

scholarly journals Photocatalytic Decomposition of N2O by Using Nanostructured Graphitic Carbon Nitride/Zinc Oxide Photocatalysts Immobilized on Foam

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 735 ◽  
Author(s):  
Kamila Kočí ◽  
Martin Reli ◽  
Ivana Troppová ◽  
Marcel Šihor ◽  
Tereza Bajcarová ◽  
...  
Keyword(s):  
Carbon Nitride ◽  
Cost Effective ◽  
Band Gap Energy ◽  
Photocatalytic Decomposition ◽  
Photocatalytic Reaction ◽  
Photocatalytic Efficiency ◽  
Ultraviolet A ◽  
Electron Hole ◽  
Gap Energy ◽  
Significant Factors

The aim of this work was to deposit cost-effective g-C3N4/ZnO nanocomposite photocatalysts (weight ratios of g-C3N4:ZnO from 0.05:1 to 3:1) as well as pure ZnO and g-C3N4 on Al2O3 foam and to study their photocatalytic efficiency for the photocatalytic decomposition of N2O, which was studied in a home-made batch photoreactor under ultraviolet A irradiation (λ = 365 nm). Based on the photocatalysis measurements, it was found that photocatalytic decomposition of N2O in the presence of all the prepared samples was significantly higher in comparison with photolysis. The photoactivity of the investigated nanocomposite photocatalysts increased in the following order: g-C3N4/ZnO (3:1) ≈ g-C3N4/ZnO (0.45:1) ≤ g-C3N4/ZnO (2:1) ZnO < g-C3N4 < g-C3N4/ZnO (0.05:1). The g-C3N4/ZnO (0.05:1) nanocomposite showed the best photocatalytic behavior and the most effective separation of photoinduced electron–hole pairs from all nanocomposites. The key roles played in photocatalytic activity were the electron–hole separation and the position and potential of the valence and conduction band. On the other hand, the specific surface area and band gap energy were not the significant factors in N2O photocatalytic decomposition. Immobilization of the photocatalyst on the foam permits facile manipulation after photocatalytic reaction and their repeated application.

One-pot synthesis of heterostructured Bi2S3/BiOBr microspheres with highly efficient visible light photocatalytic performance

RSC Advances ◽  
2015 ◽  
Vol 5 (21) ◽  
pp. 16239-16249 ◽  
Author(s):  
Hong-Peng Jiao ◽  
Xiang Yu ◽  
Zhao-Qing Liu ◽  
Pan-Yong Kuang ◽  
Yuan-Ming Zhang
Keyword(s):  
Visible Light ◽  
Fast Electron ◽  
Photocatalytic Performance ◽  
Solvothermal Method ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
One Pot ◽  
One Pot Synthesis ◽  
Hole Recombination ◽  
Visible Light Photocatalytic

To overcome the drawback of low photocatalytic efficiency brought by fast electron–hole recombination and narrow photoresponse range, the heterostructured Bi2S3/BiOBr microspheres were designed and synthesized via a facile one-pot solvothermal method.

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