Characterization of TiO2 Nanoparticles and ZnO/TiO2 Composite Obtained by Hydrothermal Method

In the present work, reduced graphene oxide/Titanium dioxide (rGO/TiO2) composites (1:1 and 1:2 wt %) have been synthesized by the hydrothermal method using graphene oxide (GO) and commercial TiO2 as precursors. Previously, we prepared the GO, in the way optimizing and making safer, the Hummers route. We have chosen the hydrothermal method to prepare the composites because it offers several advantages: 1) It consist of a very simple experimental setup, 2) it utilizes only water, instead of Hydrazine or Sulfonate used as chemical reductants in traditional methods, avoiding the incorporation of un-willing impurities into GO sheets, 3) the temperature and pressure condition reached in the closed hydrothermal system have promoted the recovery of π-conjugation after dehydration diminishing defects concentration and increasing the degree of reduction of the GO sheets, and 4) this system is compatible with industrial batch production. The structure, surface morphology, chemical composition and optical properties of GO, TiO2 and rGO/TiO2 composites have been analyzed using, TEM, FTIR, Raman- and XPS-spectroscopy. TEM micrographs show that the TiO2 nanoparticles are non-homogenously adsorbed onto the GO sheets. FTIR spectra of the rGO/TiO2 composites suggest that during the hydrothermal process the GO sheets get reduced. Raman spectra suggest that TiO2 remains with anatase structure even after the hydrothermal process. The C 1s XPS spectra of the rGO/TiO2 composites have shown a significant decrease of oxygenated carbon related signals, confirming that most of the oxygenated groups were successfully removed. Based on these characterization results we infer that, GO sheets of good quality have been successfully synthesized and the GO sheets have been partially reduced via the TiO2 nanoparticles anchored during the hydrothermal process.

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Research Synthesis of La3+ Doped TiO2 Nanoparticles by Hydrothermal Method, Study on Photocatalytic Activity of Decomposition of Methylene Blue under Ultraviolet Irradiation

VNU Journal of Science Natural Sciences and Technology ◽

10.25073/2588-1140/vnunst.4899 ◽

2019 ◽

Vol 35 (3) ◽

Author(s):

Do Thi Minh Hue ◽

Nguyen Thi Tuyet Mai ◽

Tran Van Chau ◽

Tran Thi Thu Huyen ◽

Nguyen Thi Lan ◽

...

Keyword(s):

Photocatalytic Activity ◽

Tio2 Nanoparticles ◽

Hydrothermal Method ◽

Surface Science ◽

Ultraviolet Irradiation ◽

Metal Ion ◽

Materials Science ◽

Doped Tio2 ◽

Co Doped

In this study, with the aim of improving the photocatalytic efficiency of TiO2, we studied the synthesis of La3+ doped TiO2 (with doped rates 1%, 2.5%, 5% mol/mol compared to Ti4+) by hydrothermal method. The hydrothermal condition was set at 180 °C for 12 hours. Material characteristics were investigated by XRD, SEM and solid UV-Vis methods. The results show that, all prepared materials have a crystal particle size of about nano-meters, small and smooth (4.5¸6.5 nm). La3+ doped TiO2 samples had a shift towards longer wavelengths (l» 400¸500 nm) compared to non-doped TiO2 sample (l£ 380 nm). The band gap energy (Eg) of La3+ doped TiO2 samples was reduced to 3.04¸3.10 eV . The yield of MB degradation of La3+ doped TiO2 at 5% mol/mol reached the highest ~93% after 60 minutes under ultraviolet irradiation. Keywords Anatase TiO2, photocatalysis, La3+ doped TiO2, hydrothermal method, ultraviolet irradiation. References [1] D. Nassoko, Y. F. Li, H. Wang, J. L. Li, Y. Z. Li, Y. Yu, Nitrogen-doped TiO2 nanoparticles by using EDTA as nitrogen source and soft template: Simple preparation, mesoporous structure, and photocatalytic activity under visible light, Journal of Alloys and Compounds. 540 (2012) 228-235. https://doi.org/10.1016/j.jallcom.2012.06.085.[2] M. Khatamian, S. Hashemian, A. Yavari, M. Saket, Preparation of metal ion (Fe3+ and Ni2+) doped TiO2 nanoparticles supported on ZSM-5 zeolite and investigation of its photocatalytic activity, Materials Science and Engineering B. 177 (2012) 1623-1627. http://dx.doi.org/10.1016/ j.mseb.2012.08.015.[3] X. Zhang, Q. Liu, Visible-light-induced degradation of formaldehyde over titania photocatalyst co-doped with nitrogen and nickel, Applied surface Science. 254(15) (2008) 4780-4785. https://doi.org/10.1016/j.apsusc.2008.01.094.[4] Y. Wang, H. Cheng, L. Zhang, Y. Hao, J. Ma, B. Xu, W. Li, The preparation, characterization, photoelectrochemical and photocatalytic properties of lanthanide metal-ion-doped TiO2 nanoparticles, Journal of Molecular Catalysis A: Chemical. 151 (2000) 205-216. https://doi.org/10. 1016/s 1381-1169(99)00245-9[5] M. Meksi, G. Berhault, C. Guillard, H. Kochkar, Design of TiO2 nanorods and nanotubes doped with lanthanum and comparative kinetic study in the photodegradation of formic acid, Catalysis Communications. 61 (2015) 107-111. https://doi. org/ 10.1016/j.catcom.2014.12.020.[6] Q. Wang, S. Xu, F. Shen, Preparation and characterization of TiO2 photocatalysts co-doped with iron (III) and lanthanum for the degradation of organic pollutants, Applied Surface Science. 257 (2011) 7671-7677. https://doi.org/10.1016/j. apsusc.2011.03.157.[7] L. Elsellami, H. Lachheb, A. Houas, Synthesis, characterization and photocatalytic activity of Li, Cd-, and La-doped TiO2, Materials Science in Semiconductor Processing. 36 (2015) 103-114. https://doi.org/10.1016/j.mssp.2015.03.032.[8] J. Nie, Y. Mo, B. Zheng, H. Yuan, D. Xiao, Electrochemical fabrication of lanthanum-doped TiO2 nanotube array electrode and investigation of its photoelectrochemical capability, Electrochimica Acta. 90 (2013) 589-596. http://dx.doi.org/10. 1016/j.electacta. 2012.12.049.[9] Y. Chen, Q. Wu, C. Zhou, Q. Jin, Enhanced photocatalytic activity of La and N co-doped TiO2/diatomite composite, Powder Technology. 322 (2017) 296-300. http://dx.doi.org/10.1016/ j.powtec.2017.09.026. [10] I. Ganesh, P. P. Kumar, I. Annapoorna, J. M. Sumliner, M. Ramakrishna, N. Y. Hebalkar, G. Padmanabham, G. Sundararajan, Preparation and characterization of Cu-doped TiO2 materials for electrochemical, photoelectrochemical, and photocatalytic applications, Applied Surface Science, 293 (2014) 229-247. http://dx.doi.org/10. 1016/j.apsusc.2013.12.140.

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