Optical and photocatalytic properties of rare earth metal-modified ZnO quantum dots

Sowik, Jakub; Miodyńska, Magdalena; Bajorowicz, Beata; Mikołajczyk, Alicja; Lisowski, Wojciech; Klimczuk, Tomasz; Kaczor, Daniel; Zaleska-Medynska, Adriana; Malankowska, Anna

doi:10.1016/j.apsusc.2018.09.104

Cited by 66 publications

(23 citation statements)

References 75 publications

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“…This increase can be attributed to the surface defects of vacancies created by an increase in dopant concentration in the crystalline lattice, which act as centers of radiative recombination [32,77]. The similar behavior was observed by Sowik et al [78] that reported the modification of ZnO quantum dots with rare earth metals. The modification of ZnO with small amount of rare earth metal influenced lower PL intensity, however modification of ZnO by 0.18 or more mmol of La and Er caused increased in PL emission intensity.…”

Section: Resultssupporting

confidence: 72%

Effect of Gd3+ doping on structural and photocatalytic properties of ZnO obtained by facile microwave-hydrothermal method

et al. 2019

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Gd 3+-doped ZnO nanoparticles with different Gd 3+ concentrations were synthesized by an eco-friendly microwave hydrothermal method. X-ray diffraction measurements confirm that the prepared nanoplates exhibit hexagonal wurtzite structure. Gd 3+ doping induces lattice expansion of ZnO due to the larger ionic radius of rare earth Gd 3+ in relation to Zn 2+ ions. Rietveld refinement, Raman and Photoluminescence (PL) spectra confirm that Gd 3+ ions were successfully inserted into ZnO lattice. The 2.0 mol% Gd 3+ doped sample exhibits an increased photoluminescence intensity in comparison to that for the undoped ZnO, which is attributed to the enhance in the defect concentration due to Gd 3+ doping. The photocatalytic activities of the samples were also evaluated towards UV-A induced degradation of methylene blue in aqueous solution. The highest photocatalytic activity was observed for 1.0 mol% Gd 3+-doped ZnO nanoparticles (73% for methylene blue degradation within 150 min under UV-Vis irradiation). The particles size, agglomeration degree and the electronic effects due to the Gd 3+ dopping seems to be the main parameters that affect the photocatalytic activity of Gd 3+-doped ZnO nanoparticles.

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Section: Resultssupporting

confidence: 72%

Effect of Gd3+ doping on structural and photocatalytic properties of ZnO obtained by facile microwave-hydrothermal method

et al. 2019

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“…The atomic percentage of elements in pure ZnO and ETZ2 is shown in Table S1. The atomic percentages clearly indicate oxygen vacancy in composition that will be consequently beneficial for the adsorption process which plays the role of residual centers; eventually promote the photocatalytic performance [16].…”

Section: Sem Bet Surface Area and Eds Analysismentioning

confidence: 99%

Rare earth co-doped ZnO photocatalysts: Solution combustion synthesis and environmental applications

Ahmad

Akhtar

Ahmed

et al. 2020

Separation and Purification Technology

112

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A novel europium (Eu) and terbium (Tb) co-doped ZnO nanoparticles had been synthesized by a facile, cost efficient and rapid combustion method. The physical and chemical properties of the as-synthesized nanoparticles were determined by XRD, SEM, EDS, BET, FTIR, XPS, UV-vis DRS, PL, EIS and photocurrent density. XRD patterns confirm that Eu and Tb ions are stably inserted into the framework of ZnO, and the crystallite size decreases to 21 nm compared to that of pure ZnO (32 nm) as the amount of co-dopants increases to optimal value (3 mol% of each). With the insertion of Eu and Tb ions into ZnO, the recombination rate of photo generated charge carriers is found to be low. It is observed that doped Eu and Tb ions can enter the lattice structure of ZnO with a suitable doping concentration, and the obtained doped ZnO have ordered hexagonal wurtzite structures and nearly spherical morphology with high specific surface area and high porosity. Meanwhile, the introduction of Eu and Tb ions can effectively extend the spectral response from UV to visible region for the catalysts, thus reducing the band gap from 3.25 to 2.91 eV. Further analysis by means of XPS measurement showed that the existence of mixture of Eu 2+/ Eu 3+ and Tb 3+/ Tb 4+ oxidation states and high content of the surface chemisorbed oxygen species also contributed to the high photocatalytic activity. It was found that Eu and Tb co-doped ZnO shows highly efficient and stable visible light activity and provides a 100% MB degradation within 15 min, while the degradation time for Eu doped ZnO and Tb doped ZnO is reduced gradually to 50 and 42 min, respectively to obtain the 100% MB degradation. It was also found that the photocatalytic hydrogen evolution activity over Eu and Tb co-doped ZnO can be significantly increased to 533.8 and 792 µmol with 0.2 wt% catalyst dose and initial solution pH 9, respectively under similar conditions with good stability. Moreover, simultaneous introduction of Eu and Tb effectively promoted the yield of CH 4 to 4.59 µmol, which was 3.4 fold higher in comparison to pure ZnO. Thus the present approach could provide a versatile strategy for the synthesis of novel and efficient visible light activated photocatalysts.

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“…Oxide semiconductor nanomaterials are gaining increasing interest due to their attractive functional properties related to their small particle size and hence large active surface (Dal Santo et al 2018;Sowik et al 2019). Among these features, the photocatalytic properties are of particular interest.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic properties of zirconium oxide–zinc oxide nanoparticles synthesised using microwave irradiation

2019

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ZrO 2-ZnO nanoparticles with different mass concentrations of ZrO 2 (1%, 5%, 10%, 20%) were prepared using a two-stage precipitation method with microwave irradiation. The ZrO 2-ZnO with 10% of ZrO 2 had the highest photocatalytic activity. The obtained material was characterised using XRD, which confirmed a high crystal structure in the synthesised material, and transmission electron microscopy (TEM) analysis, which depicted that micro and nano needle-shaped particles had been obtained and that irregularly shaped nanoparticles were present on the surface of those particles. TEM-EDX analysis confirmed the presence of both ZnO and ZrO 2 in the product. FT-IR analyses showed that the positions of peaks related to Zn-O and Zr-O absorption bands did not change in ZrO 2-ZnO NPs. The initial concentration of Methylene Blue (MB), the pH of the solution, and the mass of the photocatalyst were investigated to determine the photocatalytic efficiency of the material and the degree of removal of the MB. The highest efficiency (97%) was obtained in the following conditions: 30 mg/ dm 3 of the MB solution, pH 9 and 70 mg ZrO 2-ZnO after 30 min of reaction time under UV irradiation.

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Optical and photocatalytic properties of rare earth metal-modified ZnO quantum dots

Cited by 66 publications

References 75 publications

Effect of Gd3+ doping on structural and photocatalytic properties of ZnO obtained by facile microwave-hydrothermal method

Effect of Gd3+ doping on structural and photocatalytic properties of ZnO obtained by facile microwave-hydrothermal method

Rare earth co-doped ZnO photocatalysts: Solution combustion synthesis and environmental applications

Photocatalytic properties of zirconium oxide–zinc oxide nanoparticles synthesised using microwave irradiation

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