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IJAT Vol.14 No.2 pp. 184-189
doi: 10.20965/ijat.2020.p0184
(2020)

Paper:

Fabrication of SiO2-ZnO Core-Shell Urchin-Like Structure by Hydrothermal Method Using Self-Assembled Particles as Nuclei and Application to UV-Activated Gas Sensors

Daiki Funakawa and Nobuyuki Moronuki

Tokyo Metropolitan University
6-6 Asahigaoka, Hino-shi, Tokyo 191-0065, Japan

Corresponding author

Received:
June 12, 2019
Accepted:
October 23, 2019
Published:
March 5, 2020
Keywords:
ZnO, core-shell, hydrothermal method, gas sensor, UV activation
Abstract

This study aims to improve the efficiency of gas sensors with a zinc oxide (ZnO) structure by widening the surface area for reaction and using UV-activation. The silica (SiO2)-ZnO core-shell urchin-like structure is a promising candidate to achieve this aim, due to its broad surface area and electrically insulated formation. The higher resistivity of silica prevents the escape of electrons and recombination during reaction with gas; thus, improving its sensitivity. The structure was fabricated by a two-step process. First, ZnO-silica core-shell structures were produced. ZnO nanoparticles (φ≤ 34 nm) self-assembled to form a shell around a core comprising silica particles (φ5 μm). Gravity sedimentation was then used to obtain the silica particles, while the ZnO particles were obtained by dropping and drying of the suspension. Closely packed structures were obtained due to the meniscus attraction between the particles at the drying stage of the suspension. Second, ZnO urchin-like structures were synthesized on the silica particles using the hydrothermal method, with the originally placed ZnO nanoparticles as the nuclei. The method is a simple material synthesis involving the crystal growth process in a sealed container, in which substrates and precursors are stored and maintained at an elevated temperature. The obtained structure (or morphology) changed depending on the nucleation and growth conditions. The appropriate conditions were clarified through systematic experiments. Finally, the gas sensor performance was examined.

Cite this article as:
D. Funakawa and N. Moronuki, “Fabrication of SiO2-ZnO Core-Shell Urchin-Like Structure by Hydrothermal Method Using Self-Assembled Particles as Nuclei and Application to UV-Activated Gas Sensors,” Int. J. Automation Technol., Vol.14 No.2, pp. 184-189, 2020.
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References
  1. [1] L. Wang, Y. Kang, X. Liu, S. Zhang, W. Huang, and S. Wang, “ZnO nanorod gas sensor for ethanol detection,” Sensor and Actuators, B, Vol.162, pp. 237-243, 2012.
  2. [2] J. Zhang, W. X. Que, Q. Jia, and X. Ye, “Controllable hydrothermal synthesis of ZnO nanowires arrays on Al-doped ZnO seed layer and patterning of ZnO nanowires arrays via surface modification of substrate,” Applied Surface Science, Vol.257, pp. 10134-10140, 2011.
  3. [3] R. Shi, P. Yang, X. Song, and J. Wang, “ZnO flower: Self-assembly growth from nanosheets with exposed {1100} facet, white emission, and enhanced photocatalysis,” Applied Surface Science, Vol.366, pp. 506-513, 2016.
  4. [4] Z. Guo, G. Chen, G. Zheng, L. Liu, and C. Zhang, “Metal oxides and metal salt nanostructures for hydrogen sulfide sensing: mechanism and sensing performance,” RSC Adv., Vol.67, pp. 54793-54805, 2015.
  5. [5] M. Procek, A. Stolarczyk, and T. Pustelny, “Impact of Temperature and UV irradiation on Dynamics of NO2 Sensors Based on ZnO Nanostructure,” Nanomaterials, Vol.7, p. 312, 2017.
  6. [6] Y. Chen, X. Li, J. Wang, and Z. Tang, “UV activated hollow ZnO microspheres for selective ethanol sensors at low temperature,” Sensors and Actuators, B, Vol.233, pp. 158-164, 2016.
  7. [7] H. Chen, Y. Liu, C. Xie, J. Wu, D. Zeng, and Y. Liao, “A comparative study on UV light activated porous TiO2 and ZnO film sensors for gas sensing at room temperature,” Ceramics Int., Vol.38, No.1, pp. 503-509, 2012.
  8. [8] S. W. Fan, A. K. Srivastava, and V. P. Dravid, “UV-activated room-temperature gas sensing mechanism of polycrystalline ZnO,” Appl. Phys. Lett., Vol.95, 142106, 2009.
  9. [9] J. Cui, J. Jiang, L. Shi, F. Zhao, D. Wang, Y. Lin, and T. Xie, “The role of Ni doping on photoelectric gas-sensing properties of ZnO nanofibers,” RSC Adv., Vol.6, pp. 78257-78263, 2016.
  10. [10] P. Zhang, G. Pan, J. Zhen, and Y. Sun, “High sensitivity ethanol gas sensor based on Sn-doped ZnO under visible light irradiation at low temperature,” Mat. Res., Vol.17, No.4, pp. 817-822, 2014.
  11. [11] N. A. Galedari, M. Rahmani, and M. Tabihi, “Preparation, characterization, and application of ZnO@SiO2 core – shell structured catalyst for photocatalytic degradation of phenol,” Environ Sci. Pollut. Res., Vol.24, No.14, pp. 12655-12663, 2017.
  12. [12] C. Y. Huang, Y. J. Yang, J. Y. Chen, C. H. Wang, Y. F. Chen, L. S. Hong, C. S. Liu, and C. Y. Wu, “p-Si nanowires/SiO2/n-ZnO heterojunction photodiodes,” Appl. Phys. Lett., Vol.97, 013503, 2010.
  13. [13] J. W. Lee, M. R. Othman, Y. Eom, T. G. Lee, W. S. Kim, and J. Kim, “The effects of sonification and TiO2 deposition on the micro-characteristics of the thermally treated SiO2/TiO2 spherical core-shell particles for photo-catalysis of methyl orange,” Microporous and Mesoporous Materials, Vol.116, Issues 1-3, pp. 561-568, 2008.
  14. [14] N. Moronuki and Y. Okubo, “Self-assembly of ZnO particles and subsequent hydrothermal crystal growth to produce ZnO urchin-like structure and its application to gas sensor,” J. of JSPE, Vol.84, No.3, pp. 267-271, 2018.
  15. [15] D. Funakawa and N. Moronuki, “Production of ZnO regular microstructure by hydrothermal process with controlled nucleation aiming at efficient gas sensor,” Proc. of 17th Int. Conf. on Precision Engineering (ICPE2018), F-2-6, 2018.
  16. [16] N. Moronuki, “Hydrothermal synthesis with controlled nucleation and growth to produce regular structures,” euspen’s 18th Int. Conf. & Exhibition, p. 397, 2018.
  17. [17] W.-S. Chae, D. V. Gough, S.-K. Han, D. B. Robinson, and P. V. Braun, “Effect of Ordered Intermediate Porosity on Ion Transport in Hierarchically Nanoporous Electrodes,” ACS Appl. Mater. Inter., Vol.4, Issue 8, pp. 3973-3979, 2012.
  18. [18] A. Wei, X. W. Sun, C. X. Xu, Z. L. Dong, Y. Yang, S. T. Tan, and W. Huang, “Growth mechanism of tubular ZnO firmed in aqueous solution,” Nanotechnology, Vol.17, p. 1740, 2006.
  19. [19] S. Cho, J. W. Jang, S. H. Jung, B. R. Lee, E. Oh, and K. H. Lee, “Precursor effect of Citric Acid and Citrates on ZnO Crystal Formation,” Langmuir, Vol.25, No.6, pp. 3825-3831, 2009.
  20. [20] Y. F. Zhu, D. H. Fan, and W. Z. Shen, “Template-Free Synthesis of Zinc Oxide Hollow Microspheres in Aqueous Solution at Low Temperature,” J. Phys. Chem., C, Vol.111, pp. 18629-18635, 2007.
  21. [21] K. S. Kim, H. Jeong, M. S. Jeong, and G. Y. Jung, “Polymer-Templated Hydrothermal Growth of Vertically Aligned Single-Crystal ZnO Nanorods and Morphological Transformations Using Structural Polarity,” Adv. Func. Mater., Vol.20, pp. 3055-3063, 2010.
  22. [22] G. Gamov, “Matter, Earth, and Sky,” Prentice Hall, 1965.

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