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. 2019 Mar 6;9(13):7509-7535.
doi: 10.1039/c8ra09962f. eCollection 2019 Mar 1.

Synthesis of N-doped ZnO nanoparticles with cabbage morphology as a catalyst for the efficient photocatalytic degradation of methylene blue under UV and visible light

Eswaran Prabakaran  1 , Kriveshini Pillay  1
Affiliations

Synthesis of N-doped ZnO nanoparticles with cabbage morphology as a catalyst for the efficient photocatalytic degradation of methylene blue under UV and visible light

Eswaran Prabakaran et al. RSC Adv. .

Abstract

In this study, the synthesis of nitrogen-doped zinc oxide nanoparticles with a cabbage like morphology (N-ZnONCBs) by a hydrothermal method using zinc acetate dihydrate as a precursor and hydrazine monohydrate as a nitrogen source is reported. N-ZnONCB were characterized using UV-visible Spectroscopy (UV-Vis), Fluorescence Spectroscopy, Fourier Transmittance Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Dispersive Spectroscopy (EDS) and EDX elemental mapping. N-ZnONCBs were tested for their photocatalytic capabilities in the degradation of methylene blue (MB) under UV-light and visible light irradiation for about 0 to 80 minutes and 0 to 50 min respectively. The N-ZnONCB catalyst demonstrated improved photodegradation efficiency (98.6% and 96.2%) and kinetic degradation rates of MB (k = -0.0579 min-1 and k = -0.0585 min-1) under UV light and visible light irradiation at different time intervals. The photodegradation study was also evaluated with different dosages of N-ZnONCB catalyst, different initial concentrations of MB and variation in the pH (3, 5, 9 and 11) of the solution of MB under UV light and visible light irradiation. The photocatalytic degradation intermediate products were obtained by liquid chromatography mass spectra (LC-MS) and also complete mineralization was determined by using Total Organic Carbon (TOC) studies. This photocatalyst was also tested with 2,4-dichlorophenol (2,4-DCP) under visible light irradiation at different time intervals. Fluorescence and quenching studies were performed for the binding interaction between the N-ZnONCB catalyst and MB dye. A Zetasizer was used to find the charge and average size of the N-ZnONCB catalyst and also the charge of the N-ZnONCB catalyst before and after MB dye solution adsorption. The N-ZnONCB catalyst was also tested for its photostability and reusability with a percentage degradation rate of MB (93.2%) after 4 cycle experiments. These results have clearly demonstrated that the N-ZnONCB catalyst can be applied for the photocatalytic degradation of MB from wastewater samples.

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Conflict of interest statement

There are no conflicts to declare.

Figures

Scheme 1
Scheme 1. Synthesis of N-ZnONCBs catalyst by hydrothermal method.
Fig. 1
Fig. 1. Setup of photoreactor for photocatalytic degradation application.
Scheme 2
Scheme 2. Mechanism for the synthesis of N-ZnONCBs catalyst.
Fig. 2
Fig. 2. (A) FT-IR spectrum of N-ZnONCBs, (B) DRS absorption spectrum of the N-ZnONCBs, (C) fluorescence spectrum of N-ZnONCBs, (D) X-ray diffraction spectrum of N-ZnONCBs and (E) comparison of X-ray pattern of (a) pure ZnONPs and (b) N-ZnONCBs catalyst.
Fig. 3
Fig. 3. Tauc plot of the Kubelka–Munk function for (A) Pure ZnO and (B) N-ZnONCBs.
Fig. 4
Fig. 4. (A) Raman spectrum of N-ZnONCBs and (B) TGA spectrum of N-ZnONCBs.
Fig. 5
Fig. 5. (A) Barrett–Joyner–Halenda (BJH) plot of surface area of N-ZnONCBs catalyst with N2 adsorption–desorption isotherms and (B) pore size distribution plots N-ZnONCBs catalyst.
Fig. 6
Fig. 6. SEM images of N-ZnONCBs at different magnifications of (A) 200 μM, (B) 100 μM, (C and D) 50 μM, (E) 20 μM and (F) 10 μM.
Fig. 7
Fig. 7. Elemental mapping images of (A) N-ZnONCBs at 50 μM magnification, (B) Zn, (C) O, (D) N and (E) EDX spectrum of N-ZnONCBs catalyst.
Fig. 8
Fig. 8. TEM images of N-ZnONCBs of (A) 200 nm, (B) 100 nm, (C) 50 nm and (D) SAED pattern of N-ZnONCBs.
Fig. 9
Fig. 9. UV-visible spectra of MB with N-ZnONCBs catalyst (A) UV light at different time interval 0 to 80 minutes, (B) visible light with different time interval 0 to 50 minutes and (C) plot of C/C0vs. times photocatalytic degradation of MB.
Fig. 10
Fig. 10. UV-visible spectra of MB with different catalyst of N-ZnONCBs (A) 100 mg, (B) 75 mg, (C) 50 mg and (D) 25 mg under UV light with reaction time interval 0 to 80 minutes and digital images of photocatalytic degradation of MB 0 min and 80 minutes with 100 mg (A) (inset). UV-visible spectra of MB for N-ZnONCBs with different catalyst dosage of (E) 100 mg, (F) 75 mg, (G) 50 mg and (H) 25 mg under visible light irradiation with different time interval 0 to 50 minutes.
Fig. 11
Fig. 11. (A) Plot of percentage of degradation vs. times, (B) ln(C/C0) vs. times of MB with different N-ZnONCBs catalyst dosage 100 mg, 75 mg, 50 mg and 25 mg under the UV light irradiation, (C) plot of percentage of degradation vs. times and (D) ln(C/C0) vs. times of MB with different N-ZnONCBs catalyst dosage 100 mg, 75 mg, 50 mg and 25 mg under the visible light irradiation.
Fig. 12
Fig. 12. UV-visible spectra of MB with different pH of (A) 9, (B) 11, (C) 5 and (D) 3 with N-ZnONCBs under UV light irradiation at reaction time interval 0 to 80 minutes. UV-visible spectra of MB with different pH of (E) 9, (F) 11, (G) 5 and (H) 3 with N-ZnONCBs under visible light irradiation at reaction time interval 0 to 50 minutes.
Fig. 13
Fig. 13. (A) Plot of percentage of degradation vs. times, (B) ln(C/C0) vs. times of MB with different pH of 9, 11, 5 and 3 under the UV light irradiation with reaction time interval 0 to 80 minutes, (C) plot of percentage of degradation vs. times and (D) ln(C/C0) vs. times of MB with pH of 9, 11, 5 and 3 under the visible light irradiation with reaction time interval 0 to 50 minutes.
Fig. 14
Fig. 14. UV-visible spectra of MB with different initial concentration of (A) 15 ppm, (B) 20 ppm, (C) 10 ppm and (D) 5 ppm under the UV light irradiation with reaction time interval 0 to 80 minutes and digital images of photocatalytic degradation of MB 0 min and 80 minutes (A–D) (inset). UV-visible spectra of MB with different initial concentration of (E) 15 ppm, (F) 20 ppm, (G) 10 ppm and (H) 5 ppm under visible light irradiation with reaction time interval 0 to 80 minutes.
Fig. 15
Fig. 15. (A) Plot of percentage of degradation vs. times, (B) ln(C/C0) vs. times of MB with different concentration of 20 ppm, 15 ppm, 5 ppm and 3 ppm under the UV light irradiation with reaction time interval 0 to 80 minutes, (C) plot of percentage of degradation vs. times and (D) ln(C/C0) vs. times of MB with different concentration of 20 ppm, 15 ppm, 5 ppm and 3 ppm under the visible light irradiation with reaction time interval 0 to 50 minutes.
Fig. 16
Fig. 16. N-ZnONCBs catalyst reusability (A) repeat cycle experiment of MB degradation rate vs. irradiation times and (B) percentage of degradation rate vs. cycle numbers under visible light irradiation 0 to 50 minutes.
Fig. 17
Fig. 17. Fluorescence quenching spectra of MB (A) different concentration of N-ZnONCBs in water; (a) 1 × 10−6 M of MB, (b) 0.1 μM, (c) 0.2 μM, (d) 0.3 μM, (e) 0.4 μM, (f) 0.5 μM and (g) 0.6 μM at excited state at 630 nm, (B) Stern–Volmer plot of F0/F vs. concentration of N-ZNONCBs, (C) fluorescence spectra of 2,4-DCP and (D) Stern–Volmer plot of F0/F vs. time of various concentration of (a) 1 × 10−6 M of 2,4-DCP, (b) and (a) 1 × 10−6 M of MB, (b) 0.1 μM, (c) 0.2 μM, (d) 0.3 μM, (e) 0.4 μM, (f) 0.5 μM and (g) 0.6 μM at excited state at 240 nm.
Fig. 18
Fig. 18. LC-MS spectra MB (A) 10 min, (B) 20 min, (C) 30 min, (D) 40 min, (E) 50 min under the visible light irradiation N-ZnONCBs catalyst = 150 mg/400 mL, MB = 10 ppm, different time 0 to 50 min and pH 7.
Fig. 19
Fig. 19. (A) Percentage of TOC removal of MB with N-ZNOCBs catalyst under UV light irradiation (a) and visible light irradiation (b) and (B) UV-visible spectra of 1 × 10 × M of 2,4-DCP with 100 mg of N-ZnONCBs under visible light irradiation at 0 to 50 minutes.
Fig. 20
Fig. 20. (A) DLS spectrum of N-ZnONCBs and (B) zeta-potential of N-ZnONCBs dispersed in 10 ml (50 mg) of water medium with sonication 10 minutes.
Fig. 21
Fig. 21. (A) Zeta potential of N-ZnONCBs, (B) N-ZnONCBs-MB solution initial stage, (C) N-ZnONBCs-MB solution after 30 minutes adsorption and (D) to determine the zero point charge with different pH 3, pH 4, pH 5, pH 6, pH 9 and pH 10 of N-ZnONCBs with various zeta-potential.
Fig. 22
Fig. 22. Comparison for the photolysis of MB and 2,4-DCP under UV and visible light irradiation at 0 to 80 min; (A) photolysis of MB under UV light, (B) photolysis of MB under visible light, (C) photolysis of 2,4-DCP under UV light, (D) photolysis of 2,4-DCP under visible light without N-ZnONCBs catalyst.
Fig. 23
Fig. 23. Calibration plot of C/C0 photolysis of MB and 2,4-DCP under the UV and visible light irradiation with different time interval 0 to 80 minutes.
Fig. 24
Fig. 24. Mechanism of photocatalytic degradation of MB using N-ZnONCBs catalyst under visible light irradiation.
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References

    1. Hoffmann M. R. Choi W. Bahnemann D. W. Environmental Applications of Semiconductor Photocatalysis. Chem. Rev. 1995;95:69–96. doi: 10.1021/cr00033a004. - DOI
    1. Zhou H. Qu Y. Zeid T. Duan X. Towards highly efficient photocatalysts using semiconductor nanoarchitectures. Energy Environ. Sci. 2012;5:6732–6743. doi: 10.1039/C2EE03447F. - DOI
    1. Xu H. Ouyang S. Liu L. Reunchan P. Umezawa N. Ye J. Recent advances in TiO2-based photocatalysis. J. Mater. Chem. A. 2014;2:12642–12661. doi: 10.1039/C4TA00941J. - DOI
    1. Hu Y. Gao X. Yu L. Wang Y. Ning J. Xu S. Lou X. W. Carbon-Coated CdS Petalous Nanostructures with Enhanced Photostability and Photocatalytic Activity. Angew. Chem., Int. Ed. 2013;52:5636–5639. doi: 10.1002/anie.201301709. - DOI - PubMed
    1. Hu Y. F. Zhou J. Yeh P. H. Li Z. Wei T. Y. Wang Z. L. Super-sensitive, fast-response nanowire sensors by using schottky contacts. Adv. Mater. 2010;22:3327–3332. doi: 10.1002/adma.201000278. - DOI - PubMed