本研究採用水熱法成功合成了二硫化鉬（MoS2）奈米花辦球狀結構，並透過調節不同的生長溫度和生長條件進行最佳化。製備出的 MoS2 被應用於室溫下測量 NO2 氣體的感測器中，旨在探索其氣體感測性能及最佳化途徑。
首先，我們詳細描述了 MoS2 的水熱合成過程及其影響因素。透過變化的生長溫度和時間，我們觀察到 MoS2 奈米結構在不同條件下的形貌和晶體結構變化。實驗結果顯示，在 180°C 生長 36 小時，並經過 300°C 退火處理的條件下，MoS2 表現出最優的晶體結構和形貌，以及最佳的氣體感測性能。
其次，我們進行了詳盡的氣體感測性能測試和分析。利用 X 光薄膜微區繞射儀（XRD）、掃描式電子顯微鏡（SEM）以及高解析穿透式電子顯微鏡(HR-TEM)等技術對合成的 MoS2 進行表徵，並使用 BET 等溫線分析其比表面積。透過 X 射線光電子能譜（XPS）測量，驗證了合成 MoS2 的元素組成及結晶性質。實驗結果顯示，優化後的 MoS2 樣品在室溫下對 NO2 氣體具有較高的響應度、選擇性和良好的穩定性，與其優化後的晶體結構及硫空缺有密切關係。
最後，本文總結了研究結果並討論了其在環境監測和氣體感測應用中的潛在價值。透過優化合成條件和後續的退火處理，我們成功提升了 MoS2 在室溫下的氣體感測性能，為其在實際應用中的廣泛應用奠定了基礎。
綜上所述，水熱合成的 MoS2 在室溫下具有良好的氣體感測特性，未來的研究將持續探討其在環境監測及其他感測領域的應用前景。

This study successfully synthesized MoS2 nanoflower structures using the hydrothermal method and optimized them by adjusting different growth temperatures and times. The synthesized MoS2 was applied in the development of gas sensors for detecting NO2 gas at room temperature, aiming to explore its gas sensing performance and optimization pathways.
Firstly, we detailed the hydrothermal synthesis process of MoS2 and its influencing factors. By varying the growth temperature and time, we observed changes in the morphology and crystal structure of MoS2 nanostructures under different conditions. Experimental results demonstrated that MoS2 exhibited optimal crystal structure and morphology when grown at 180°C for 36 hours followed by annealing at 300°C, which also resulted in the best gas sensing performance.
Secondly, comprehensive gas sensing performance tests and analyses were conducted. Characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were employed to characterize the synthesized MoS2. Additionally, BET surface area analysis was performed. X-ray photoelectron spectroscopy (XPS) measurements verified the elemental composition of the synthesized MoS2. Experimental results showed that the optimized MoS2samples exhibited high sensitivity, selectivity, and stability towards NO2 gas at room temperature, which correlated closely with its optimized crystal structure and sulfur vacancies.
Finally, this paper summarizes the research findings and discusses the potential applications of MoS2 in environmental monitoring and gas sensing. Through optimization of synthesis conditions and subsequent annealing treatments, we successfully enhanced the gas sensing performance of MoS2 at room temperature, laying a solid foundation for its widespread application in practical settings.
In conclusion, hydrothermally synthesized MoS2 demonstrates excellent gas sensing characteristics at room temperature, highlighting promising applications in environmental monitoring and other sensing fields. Future research will continue to explore its potential in these areas.

[1] B. Brunekreef and S. T. Holgate, "Air pollution and health," The lancet, vol. 360, no. 9341, pp. 1233-1242, 2002.
[2] L. H. Tecer, O. Alagha, F. Karaca, G. Tuncel, and N. Eldes, "Particulate Matter (PM2.5, PM10-2.5, and PM10) and Children's Hospital Admissions for Asthma and Respiratory Diseases: A Bidirectional Case-Crossover Study," Journal of Toxicology and Environmental Health, Part A, vol. 71, no. 8, pp. 512-520, 2008/03/12 2008.
[3] T.-M. Chen, W. G. Kuschner, J. Gokhale, and S. Shofer, "Outdoor Air Pollution: Nitrogen Dioxide, Sulfur Dioxide, and Carbon Monoxide Health Effects," The American Journal of the Medical Sciences, vol. 333, no. 4, pp. 249-256, 2007/04/01/ 2007.
[4] W. Li, H. Li, R. Qian, S. Zhuo, P. Ju, and Q. Chen, "CTAB enhanced room-temperature detection of NO2 based on MoS2-reduced graphene oxide nanohybrid," Nanomaterials, vol. 12, no. 8, p. 1300, 2022.
[5] R. K. Sonker, S. Sabhajeet, S. Singh, and B. Yadav, "Synthesis of ZnO nanopetals and its application as NO2 gas sensor," Materials Letters, vol. 152, pp. 189-191, 2015.
[6] S. R. Gawali et al., "Ce doped NiO nanoparticles as selective NO2 gas sensor," Journal of Physics and Chemistry of Solids, vol. 114, pp. 28-35, 2018.
[7] S. Maeng, S.-W. Kim, D.-H. Lee, S.-E. Moon, K.-C. Kim, and A. Maiti, "SnO2 nanoslab as NO2 sensor: identification of the NO2 sensing mechanism on a SnO2 surface," ACS applied materials & interfaces, vol. 6, no. 1, pp. 357-363, 2014.
[8] P. Xu et al., "High aspect ratio In2O3 nanowires: synthesis, mechanism and NO2 gas-sensing properties," Sensors and Actuators B: Chemical, vol. 130, no. 2, pp. 802-808, 2008.
[9] Y. Gönüllü, A. A. Haidry, and B. Saruhan, "Nanotubular Cr-doped TiO2 for use as high-temperature NO2 gas sensor," Sensors and Actuators B: Chemical, vol. 217, pp. 78-87, 2015.
[10] W. Choi, N. Choudhary, G. H. Han, J. Park, D. Akinwande, and Y. H. Lee, "Recent development of two-dimensional transition metal dichalcogenides and their applications," Materials Today, vol. 20, no. 3, pp. 116-130, 2017.
[11] A. Splendiani et al., "Emerging photoluminescence in monolayer MoS2," Nano letters, vol. 10, no. 4, pp. 1271-1275, 2010.
[12] X. Zhang, G. Ma, and J. Wang, "Hydrothermal synthesis of two-dimensional MoS2 and its applications," Tungsten, vol. 1, no. 1, pp. 59-79, 2019.
[13] Y. Zhang, W. Zeng, and Y. Li, "Hydrothermal synthesis and controlled growth of hierarchical 3D flower-like MoS2 nanospheres assisted with CTAB and their NO2 gas sensing properties," Applied Surface Science, vol. 455, pp. 276-282, 2018.
[14] A. Rabenau, "The role of hydrothermal synthesis in preparative chemistry," Angewandte Chemie International Edition in English, vol. 24, no. 12, pp. 1026-1040, 1985.
[15] Y. X. Gan, A. H. Jayatissa, Z. Yu, X. Chen, and M. Li, "Hydrothermal synthesis of nanomaterials," Journal of Nanomaterials, vol. 2020, 2020.
[16] D. Kohl, "Function and applications of gas sensors," Journal of Physics D: Applied Physics, vol. 34, no. 19, p. R125, 2001.
[17] S. R. Morrison, "Semiconductor gas sensors," Sensors and Actuators, vol. 2, pp. 329-341, 1981.
[18] T. Ritter, J. Zosel, and U. Guth, "Solid electrolyte gas sensors based on mixed potential principle–A review," Sensors and Actuators B: Chemical, vol. 382, p. 133508, 2023.
[19] C.-H. Han, D.-W. Hong, S.-D. Han, J. Gwak, and K. C. Singh, "Catalytic combustion type hydrogen gas sensor using TiO2 and UV-LED," Sensors and Actuators B: Chemical, vol. 125, no. 1, pp. 224-228, 2007.
[20] X. Tian et al., "Recent advances in MoS 2-based nanomaterial sensors for room-temperature gas detection: A review," Sensors & Diagnostics, vol. 2, no. 2, pp. 361-381, 2023.
[21] N. T. Thang, N. H. Thoan, C. M. Hung, N. Van Duy, N. Van Hieu, and N. D. Hoa, "Controlled synthesis of ultrathin MoS 2 nanoflowers for highly enhanced NO 2 sensing at room temperature," RSC advances, vol. 10, no. 22, pp. 12759-12771, 2020.
[22] Z. Li, X. Meng, and Z. Zhang, "Equilibrium and kinetic modelling of adsorption of Rhodamine B on MoS2," Materials Research Bulletin, vol. 111, pp. 238-244, 2019.
[23] T. T. Xuan, L. N. Long, and T. Van Khai, "Effect of reaction temperature and reaction time on the structure and properties of MoS2 synthesized by hydrothermal method," Vietnam Journal of Chemistry, vol. 58, no. 1, pp. 92-100, 2020.
[24] N. T. Thang et al., "Controlled synthesis of ultrathin MoS(2) nanoflowers for highly enhanced NO(2) sensing at room temperature," RSC Adv, vol. 10, no. 22, pp. 12759-12771, Mar 30 2020.
[25] C. M. Lee et al., "Enhanced gas sensing performance of hydrothermal MoS2 nanosheets by post-annealing in hydrogen ambient," Bulletin of the Chemical Society of Japan, vol. 92, no. 6, pp. 1094-1099, 2019.
[26] L. Yu et al., "Hierarchical 3D flower-like MoS2 spheres: post-thermal treatment in vacuum and their NO2 sensing properties," Materials Letters, vol. 183, pp. 122-126, 2016.
[27] X. Zhang et al., "Hydrothermal synthesis and characterization of 3D flower-like MoS2 microspheres," Materials Letters, vol. 148, pp. 67-70, 2015.
[28] C. Lee, H. Yan, L. E. Brus, T. F. Heinz, J. Hone, and S. Ryu, "Anomalous lattice vibrations of single-and few-layer MoS2," ACS nano, vol. 4, no. 5, pp. 2695-2700, 2010.
[29] H. Li et al., "From bulk to monolayer MoS2: evolution of Raman scattering," Advanced Functional Materials, vol. 22, no. 7, pp. 1385-1390, 2012.
[30] D. Jang and M.-W. Kwon, "Self-rectifying Resistive Switching Memory based on Molybdenum disulfide for Low Power Synapse Array," 2023.
[31] G. Li et al., "Synthesis and characterization of hollow MoS2 microspheres grown from MoO3 precursors," Journal of Alloys and Compounds, vol. 501, no. 2, pp. 275-281, 2010.
[32] Y.-X. Zeng, X.-W. Zhong, Z.-Q. Liu, S. Chen, and N. Li, "Preparation and enhancement of thermal conductivity of heat transfer oil‐based MoS2 nanofluids," Journal of Nanomaterials, vol. 2013, no. 1, p. 270490, 2013.
[33] J. Kibsgaard, Z. Chen, B. N. Reinecke, and T. F. Jaramillo, "Engineering the surface structure of MoS2 to preferentially expose active edge sites for electrocatalysis," Nature materials, vol. 11, no. 11, pp. 963-969, 2012.
[34] W. Zhou et al., "Synthesis of few‐layer MoS2 nanosheet‐coated TiO2 nanobelt heterostructures for enhanced photocatalytic activities," small, vol. 9, no. 1, pp. 140-147, 2013.
[35] S. Sunu, E. Prabhu, V. Jayaraman, K. Gnanasekar, T. Seshagiri, and T. Gnanasekaran, "Electrical conductivity and gas sensing properties of MoO3," Sensors and Actuators B: Chemical, vol. 101, no. 1-2, pp. 161-174, 2004.
[36] R. Kumar, P. K. Kulriya, M. Mishra, F. Singh, G. Gupta, and M. Kumar, "Highly selective and reversible NO2 gas sensor using vertically aligned MoS2 flake networks," Nanotechnology, vol. 29, no. 46, p. 464001, 2018.
[37] W. Li et al., "Gas sensors based on mechanically exfoliated MoS2 nanosheets for room-temperature NO2 detection," Sensors, vol. 19, no. 9, p. 2123, 2019.
[38] H. Lin, X. Chen, H. Li, M. Yang, and Y. Qi, "Hydrothermal synthesis and characterization of MoS2 nanorods," Materials letters, vol. 64, no. 15, pp. 1748-1750, 2010.
[39] D. Wang, Z. Pan, Z. Wu, Z. Wang, and Z. Liu, "Hydrothermal synthesis of MoS2 nanoflowers as highly efficient hydrogen evolution reaction catalysts," Journal of Power Sources, vol. 264, pp. 229-234, 2014.
[40] R. K. Chava, J. Y. Do, and M. Kang, "Hydrothermal growth of two dimensional hierarchical MoS2 nanospheres on one dimensional CdS nanorods for high performance and stable visible photocatalytic H2 evolution," Applied Surface Science, vol. 433, pp. 240-248, 2018.
[41] S. Singh, S. Sharma, R. C. Singh, and S. Sharma, "Hydrothermally synthesized MoS2-multi-walled carbon nanotube composite as a novel room-temperature ammonia sensing platform," Applied Surface Science, vol. 532, p. 147373, 2020.
[42] J. Wang, Q. Zhou, Z. Lu, Z. Wei, and W. Zeng, "Gas sensing performances and mechanism at atomic level of Au-MoS2 microspheres," Applied Surface Science, vol. 490, pp. 124-136, 2019.
[43] X. Liu et al., "Design of superior ethanol gas sensor based on indium oxide/molybdenum disulfide nanocomposite via hydrothermal route," Applied Surface Science, vol. 447, pp. 49-56, 2018.
[44] Z. Liang et al., "One-pot hydrothermal synthesis of self-assembled MoS2/WS2 nanoflowers for chemiresistive room-temperature NO2 sensors," Sensors and Actuators B: Chemical, vol. 403, p. 135215, 2024.
[45] S. Zhao, J. Xue, and W. Kang, "Gas adsorption on MoS2 monolayer from first-principles calculations," Chemical Physics Letters, vol. 595, pp. 35-42, 2014.
[46] S. S. Shendage et al., "Characterization and gas sensing properties of spin coated WO3 thin films," Zeitschrift für Physikalische Chemie, vol. 234, no. 11-12, pp. 1819-1834, 2020.
[47] M. Gomaa, M. Sayed, V. Patil, M. Boshta, and P. Patil, "Gas sensing performance of sprayed NiO thin films toward NO2 gas," Journal of Alloys and Compounds, vol. 885, p. 160908, 2021.
[48] H. J. Kim et al., "SnO 2 nanowire gas sensors for detection of ppb level NOx gas," Adsorption, vol. 25, pp. 1259-1269, 2019.
[49] A. Sadek, "Characterization of ZnO nanobelt-based gas sensor for H-2," N02, and hydrocarbon sensing, pp. 5-6, 2007.
[50] D. Liu, Z. Tang, and Z. Zhang, "Comparative study on NO2 and H2S sensing mechanisms of gas sensors based on WS2 nanosheets," Sensors and Actuators B: Chemical, vol. 303, p. 127114, 2020.
[51] P. Chen, J. Hu, M. Yin, W. Bai, X. Chen, and Y. Zhang, "MoS2 nanoflowers decorated with Au nanoparticles for visible-light-enhanced gas sensing," ACS Applied Nano Materials, vol. 4, no. 6, pp. 5981-5991, 2021.
[52] J. Hu, X. Liu, J. Zhang, X. Gu, and Y. Zhang, "Plasmon-activated NO2 sensor based on Au@ MoS2 core-shell nanoparticles with heightened sensitivity and full recoverability," Sensors and Actuators B: Chemical, vol. 382, p. 133505, 2023.
[53] Y. Zhou, C. Zou, X. Lin, and Y. Guo, "UV light activated NO2 gas sensing based on Au nanoparticles decorated few-layer MoS2 thin film at room temperature," Applied Physics Letters, vol. 113, no. 8, 2018.