在過去的幾十年中，新型的氣體感測器已被應用於環境分析、汽車產業、醫療應用及室內空氣品質監控等的領域。隨著對環境和人體健康關注提升，對含有NH3，H2，CO，CO2，NO2和SO2的有害氣體的監測需求也隨之增長,其中氨氣（NH3）和氫氣（H2）是普遍存在各種製造過程及使用的化學物質中，因此在這些有害氣體中，其有效偵測相對來說較重要。由於受到材料科學和工程學領域的創新以及對感測器的研發和進步，基於半導體金屬氧化物材料的過渡金屬二鹵化物和導電聚合物的氨氣和氫氣的氣體感測器尺寸大幅的縮小，生產成本和耗能也隨之降低。近年來，由於氨氣和氫氣在各種工業領域是中常用的氣體，又常存在於具有能夠危害人類健康和環境的高毒性和腐蝕性的藥劑，因此對氨氣和氫氣檢測的靈敏度、選擇性和準確率的感測技術需具有高度的要求。氨氣和氫氣感測器的製造方法可以分為機械剝離法或（剝離法，Scotch Tape），溶劑熱法，化學氣相沉積（CVD），超音波處理技術，液態剝離法。

通過聚甲基丙烯酸甲酯（Polymethyl methacrylate, PMMA）製成的高靈敏度氨氣和氫氣的氣體感測器可有助於MoS2的多層奈米層片和摻雜有氧化鋅（ZnO）的MoSe2奈米層片的剝離。本研究採用超音波處理技術，將過渡金屬二鹵化物與PMMA基材混合，成功製備了PMMA-MoS2奈米高分子複合材料。同樣地，也可藉由超音波處理技術來製備MoSe2-ZNRs奈米混合材料。另外也利用了掃描電子顯微鏡（SEM）、場發射掃描電子顯微鏡（FE-SEM）、傅立葉變換紅外光譜儀（FTIR）、X射線光電子能譜儀（XPS）、拉曼光譜儀、熱重分析（TGA）和X射線繞射（XRD）解析PMMA-MoS2複合材料和MoSe2-ZnO混合奈米材料的結構和形態。高解析場發射穿透式電子顯微鏡（HRTEM）和原子力顯微鏡（AFM）的分析結果表明，在MoS2層板上的PMMA的表面塗層薄且均勻。 除此之外，UV-Vis光譜儀也用來研究其電光(electro-optical)性質。

從PMMA-MoS2奈米複合材料和MoSe2-ZNRs混合材料得到的氣體偵測性質，表明兩者分別具有優異的靈敏度、選擇性、穩定性、反應時間以及氨氣和氫氣的恢復時間。此外、製備的PMMA-MoS2奈米複合材料和MoSe2-ZNRs混合材料氣體傳感器在對抗NH3，H2，C3H6O和CO2等干擾氣體時也具有優秀的選擇性。研究結果證明，在常溫下藉由超音波處理剝離MoS2和與PMMA和MoSe2-ZNRs組成的奈米複合材料能夠改善對氨氣和氫氣等氣體的監測。與現有MoS2系統的氨氣感測器相比，PMMA-MoS2奈米複合材料具有優異的氣體感測性能。此外、與最近研發的感測器相比，MoSe2-ZNRs雜化納米材料更具優越的氫氣敏感性

In the last decades, novel gas sensors have been developed and employed in diverse fields for applications such as environmental analysis, automotive industry, medical applications, and indoor air quality controls. Specially, there has been an increasing need for monitoring hazardous gases including NH3, H2, CO, CO2, NO2, and SO2 as concerns over environment and human health. Among these hazardous gas species, ammonia (NH3) and hydrogen (H2) gases detection have attracted considerable attention in the field of gas sensor, which are important because these gases are the most common chemicals manufactured and applied in diverse areas around the world. The development of NH3 and H2 gas sensors based on semiconducting metal oxides, transitional metal dichalcogenides and conducting polymer are driven by innovations in material science and engineering, and scaling down of sensor devices. The advances in scaling down strongly decreased size, production cost and power consumption of ammonia and hydrogen gas sensors. In recent years, sensitive, selective and accurate sensing techniques for ammonia and hydrogen gas detection have been highly required since ammonia and hydrogen are both commonly utilized gases in various industrial sectors and a highly toxic and corrosive agent that can threat human health and environment. Ammonia and hydrogen gases sensors fabricated using different methods such as mechanical (or ‘Scotch Tape’ exfoliation), solvothermal, hydrothermal chemical vapor deposition (CVD), ultra-sonication technique, liquid exfoliation.

A highly sensitive NH3 and H2 gas sensors fabricated through the poly (methyl meth acrylate) (PMMA) assisted exfoliation of MoS2 based multilayered nanosheets and MoSe2 nanosheet doped at zinc oxide (ZnO), respectively. The PMMA-MoS2 nanocomposites were successfully prepared by using ultra-sonication technique of bulk transitional metal dichalcogenides exfoliated and blended with PMMA matrix. Similarly, MoSe2-ZNRs hybrid nanomaterial prepared by using ultra sonication. The physical-chemical properties of PMMA have assisted MoS2 nanocomposites and MoSe2-ZNRs hybrid materials evaluated by various analytical tools.

We have also investigated the structure and morphology of the PMMA-MoS2 composite and MoSe2-ZnO hybrids nanomaterial using Scanning Electron Microcopy (SEM), Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infra-Red (FTIR) Spectrometer, X-ray Photoelectron Spectroscopy (XPS), Raman Spectrometer, Thermogravimetric Analysis (TGA) and X-Ray Diffraction (XRD). High resolution Transmission Electron Microscopy (TEM) and AFM results revealed that uniform and thin surface coating of PMMA on the MoS2 sheets. In addition to this, the electro-optical property will be investigated by using UV-Vis Spectrometer.

The sensing properties for obtained PMMA-MoS2 nanocomposite and MoSe2-ZNRs hybrid materials exhibited an excellent sensitivity, selectivity, stability, response time and recovery time to NH3 and H2 gases, respectively. Moreover, the fabricated PMMA-MoS2 nanocomposites and MoSe2-ZNRs hybrid gas sensors possessed excellent selectivity against the interfering gases such as NH3, H2, C3H6O, and CO2. The results proved that PMMA-MoS2 composites and MoSe2-ZNRs hybrid material were prepared by ultra-sonication at room temperature, which are promising sensing materials towards NH3.and H2, respectively. The superior gas sensing properties of this present PMMA-MoS2 nanocomposites sustainable compared with the existing MoS2 based NH3 sensors to-date. In addition, MoSe2-ZNRs hybrid nanomaterial superior H2 gas sensor compared to recently studied sensors.

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