ZnO nanostructures with different morphology for enhanced photocatalytic activity

Peter, I. John; Praveen, E.; Vignesh, G.; Nithiananthi, P.

doi:10.1088/2053-1591/aa9d5d

Cited by 39 publications

(10 citation statements)

References 40 publications

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“…However, these methods often lead to incomplete decomposition of dyes and simply shift the pollutants from one phase to another, resulting in the creation of secondary pollutants that demand further management [7,8]. In the present day, increased attention is directed toward advanced oxidation processes (AOPs), which utilize semiconducting materials as a viable substitute for traditional approaches [9]. The aforementioned procedures offer several benefits, such as reduced equipment demands, indiscriminate oxidation, straightforward operational control, cost efficiency, and complete conversion of organic dyes into harmless byproducts [10].…”

Section: Introductionmentioning

confidence: 99%

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

Gatou,

Kontoliou,

Volla

et al. 2023

Catalysts

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Zinc oxide (ZnO) possesses exceptional potential to be utilized in water and wastewater treatment applications, either as a photocatalyst or in membrane incorporation. In the present study, ZnO nanoparticles were synthesized using the precipitation method. The Taguchi approach with the L32b orthogonal array was utilized in order to optimize the experimental conditions for the synthesis of the nanoparticles and to ensure that relatively smaller-sized particles were obtained. The design was characterized by ten factors, where nine of them possessed four levels, while one had two levels. This study’s design factors were the type of Zn precursor, the concentration of the Zn precursor, the type of precipitating agent, the precipitation agent’s concentration, the type of utilized solvent, the pH value of the solvent, the temperature used during the synthetic procedure, the calcination temperature, the time of stirring during synthesis, as well as the stirring speed. The influences of those factors on the selected response parameters (the average crystallite size, degree of crystallinity, energy band gap (Eg), and photodegradation constant (k)) were then evaluated. XRD analysis and the calculated Eg values indicated that the hexagonal wurtzite structure was the only crystalline phase present in the produced samples. The photocatalytic efficiency of all ZnO nanoparticles was examined in the degradation of rhodamine B under UV light irradiation. The optimal conditions were achieved using zinc acetate dihydrate as the Zn precursor at a concentration equal to 0.3 M, sodium hydroxide as the precipitating agent (1.5 M), methanol as the solvent (the pH value of the solvent was equal to 13), a temperature during the synthetic procedure of 70 °C, 600 °C as calcination temperature, a 90 min stirring time, and 700 rpm as the stirring speed. The optimized ZnO sample was synthesized based on the aforementioned conditions and thoroughly characterized. The acquired results confirmed the prediction of the Taguchi approach, and the most enhanced k-value was observed.

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Section: Introductionmentioning

confidence: 99%

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

Gatou,

Kontoliou,

Volla

et al. 2023

Catalysts

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“…However, these approaches often result in partial dye degradation and merely shift the contaminants from one phase to another, leading to the generation of secondary pollutants that necessitate additional treatment [8,9]. At present, there is growing attention towards advanced oxidation processes (AOPs) that utilize semiconducting materials as a viable alternative to traditional methods [10]. These processes offer several advantages, including simplified equipment requirements, non-selective oxidation, facile operational control, cost effectiveness, and thorough decomposition of organic dyes into benign byproducts [11].…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of Rhodamine B and Phenol Using TiO2/SiO2 Composite Nanoparticles: A Comparative Study

Gatou,

Fiorentis,

Lagopati

et al. 2023

Water

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Organic pollutants found in industrial effluents contribute to significant environmental risks. Degradation of these pollutants, particularly through photocatalysis, is a promising strategy ensuring water purification and supporting wastewater treatment. Thus, photodegradation of rhodamine B and phenol under visible-light irradiation using TiO2/SiO2 composite nanoparticles was within the main scopes of this study. The nanocomposite was synthesized through a wet impregnation method using TiO2 and SiO2 nanopowders previously prepared via a facile sol–gel approach and was fully characterized. The obtained results indicated a pure anatase phase, coupled with increased crystallinity (85.22%) and a relative smaller crystallite size (1.82 nm) in relation to pure TiO2 and SiO2 and an enhanced specific surface area (50 m2/g) and a reduced energy band gap (3.18 eV). Photodegradation of rhodamine B upon visible-light irradiation was studied, showing that the TiO2/SiO2 composite reached total (100%) degradation within 210 min compared to pure TiO2 and SiO2 analogues, which achieved a ≈45% and ≈43% degradation rate, respectively. Similarly, the composite catalyst presented enhanced photocatalytic performance under the same irradiation conditions towards the degradation of phenol, leading to 43.19% degradation within 210 min and verifying the composite catalyst’s selectivity towards degradation of rhodamine B dye as well as its enhanced photocatalytic efficiency towards both organic compounds compared to pure TiO2 and SiO2. Additionally, based on the acquired experimental results, ●O2−, h+ and e− were found to be the major reactive oxygen species involved in rhodamine B’s photocatalytic degradation, while ●OH radicals were pivotal in the photodegradation of phenol under visible irradiation. Finally, after the TiO2/SiO2 composite catalyst was reused five times, it indicated negligible photodegradation efficiency decrease towards both organic compounds.

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“…However, these methods lead to incomplete dye degradation and only transfer the contaminant from one phase to another [ 11 ]. Advanced Oxidation Processes (AOPs), based on semiconducting materials, have emerged in recent years as an alternative to conventional methods [ 12 ]. Indeed, through these processes, reactive species such as hydroxyl radicals can be generated and used as active species to oxidize the organic contaminants quickly and non-selectively.…”

Section: Introductionmentioning

confidence: 99%

“…Such defects generate mid-bandgap energy levels which are reported to increase carrier trapping leading to rapid non-radiative recombination of the electron–hole pairs within the semiconducting materials. Although doping can be used to enhance the general efficiency of the photocatalyst, many contributions to a changing performance have to be considered, such as preparation method [ 23 ], particle morphology [ 12 , 24 ], surface properties [ 25 , 26 ] and defects [ 27 ], dopant concentration [ 2 ] as well as the charge transfer dynamics of the discoloration process [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Performance of Undoped and Al-Doped ZnO Nanoparticles in the Degradation of Rhodamine B under UV-Visible Light:The Role of Defects and Morphology

Piras

Olla

Reekmans

et al. 2022

IJMS

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Quasi-spherical undoped ZnO and Al-doped ZnO nanoparticles with different aluminum content, ranging from 0.5 to 5 at% of Al with respect to Zn, were synthesized. These nanoparticles were evaluated as photocatalysts in the photodegradation of the Rhodamine B (RhB) dye aqueous solution under UV-visible light irradiation. The undoped ZnO nanopowder annealed at 400 °C resulted in the highest degradation efficiency of ca. 81% after 4 h under green light irradiation (525 nm), in the presence of 5 mg of catalyst. The samples were characterized using ICP-OES, PXRD, TEM, FT-IR, 27Al-MAS NMR, UV-Vis and steady-state PL. The effect of Al-doping on the phase structure, shape and particle size was also investigated. Additional information arose from the annealed nanomaterials under dynamic N2 at different temperatures (400 and 550 °C). The position of aluminum in the ZnO lattice was identified by means of 27Al-MAS NMR. FT-IR gave further information about the type of tetrahedral sites occupied by aluminum. Photoluminescence showed that the insertion of dopant increases the oxygen vacancies reducing the peroxide-like species responsible for photocatalysis. The annealing temperature helps increase the number of red-emitting centers up to 400 °C, while at 550 °C, the photocatalytic performance drops due to the aggregation tendency.

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ZnO nanostructures with different morphology for enhanced photocatalytic activity

Cited by 39 publications

References 40 publications

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

Optimization of ZnO Nanoparticles’ Synthesis via Precipitation Method Applying Taguchi Robust Design

Photodegradation of Rhodamine B and Phenol Using TiO2/SiO2 Composite Nanoparticles: A Comparative Study

Photocatalytic Performance of Undoped and Al-Doped ZnO Nanoparticles in the Degradation of Rhodamine B under UV-Visible Light:The Role of Defects and Morphology

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