近年來，環境污染和健康問題受到越來越多的關注，使得開發高性能、靈敏的氣體感測器成為研究的重點。在眾多材料中，MXene作為一種新型二維材料，由於其優異的電導性、大的表面積和多功能潛力，已成為氣體感測器的有希望的候選材料。基於MXene的氣體感測器透過表面吸附和電子結構的變化來檢測環境中的微量氣體。研究表明，材料中的缺陷在感測過程中起著至關重要的作用。缺陷不僅提供了額外的活性位點來增強氣體分子的吸附，而且還影響材料的表面電子密度，提高感測器對特定氣體的選擇性和靈敏度。
為了提高氣體感測器的性能，許多研究集中在調節MXene中的缺陷濃度和類型。例如，透過化學蝕刻或熱處理產生更多的空位或層間缺陷可以顯著增強氣體吸附效果。此外，透過精確控制缺陷位置和結構可以有效調整MXene的功函數和電子結構，進一步改善感測器的響應特性。但一些研究也指出，過多的缺陷可能會損害材料的穩定性，對氣體感測器的長期可靠性構成挑戰。因此，設計具有最佳缺陷分佈的MXene材料是提高感測器性能的關鍵方面。
本研究以缺陷工程為重點，系統性地研究了MXene缺陷對氣體感測器靈敏度和穩定性的影響。研究結果表明，透過控制蝕刻參數產生的精細調整的缺陷結構可以同時增強氣體吸附能力並保持材料的導電性和結構穩定性，實現高靈敏度和持久的氣體感測器性能。

In recent years, environmental pollution and health concerns have drawn increasing attention, making the development of high-performance and sensitive gas sensors a research focus. Among various materials, MXene, a novel 2D material, has emerged as a promising candidate for gas sensors due to its exceptional electrical conductivity, large surface area, and multifunctional potential. MXene-based gas sensors detect trace gases in the environment through surface adsorption and changes in electronic structure. Studies have shown that defects in the material play a critical role in the sensing process. Defects not only provide additional active sites to enhance gas molecule adsorption but also influence the surface electron density of the material, improving the selectivity and sensitivity of the sensor for specific gases.
To enhance the performance of gas sensors, many studies have focused on regulating the defect concentration and types in MXene. For instance, creating more vacancies or interlayer defects through chemical etching or thermal treatment can significantly enhance gas adsorption effects. Additionally, precise control over defect locations and structures can effectively adjust the work function and electronic structure of MXene, further improving the sensor's response characteristics. However, some studies have also pointed out that an excessive number of defects might compromise the material's stability, posing challenges to the long-term reliability of the gas sensor. Therefore, designing MXene materials with optimal defect distribution is a critical aspect of enhancing sensor performance.
This study focuses on defect engineering and systematically investigates the impact of MXene defects on the sensitivity and stability of gas sensors. The findings reveal that finely tuned defect structures, generated through controlled etching parameters, can simultaneously enhance gas adsorption capacity and maintain the material's conductivity and structural stability, achieving highly sensitive and long-lasting gas sensor performance.

1. Geim AK, Novoselov KS. The rise of graphene. Nature materials. 2007;6(3):183-91.
2. Dong Y, Shi H, Wu ZS. Recent advances and promise of MXene‐based nanostructures for high‐performance metal ion batteries. Advanced Functional Materials. 2020;30(47):2000706.
3. Anasori B, Gogotsi ÛG. 2D metal carbides and nitrides (MXenes): Springer; 2019.
4. Pandey M, Deshmukh K, Raman A, Asok A, Appukuttan S, Suman G. Prospects of MXene and graphene for energy storage and conversion. Renewable and Sustainable Energy Reviews. 2024;189:114030.
5. Novoselov KS, Geim AK, Morozov SV, Jiang D-e, Zhang Y, Dubonos SV, et al. Electric field effect in atomically thin carbon films. science. 2004;306(5696):666-9.
6. Naguib M, Kurtoglu M, Presser V, Lu J, Niu J, Heon M, et al. Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2. MXenes: Jenny Stanford Publishing; 2023. p. 15-29.
7. Jin S, Guo Y, Wang F, Zhou A. The synthesis of MXenes. Mrs Bulletin. 2023;48(3):245-52.
8. Guan X, Yang Z, Zhou M, Yang L, Peymanfar R, Aslibeiki B, et al. 2D MXene nanomaterials: synthesis, mechanism, and multifunctional applications in microwave absorption. Small Structures. 2022;3(10):2200102.
9. Cao M-S, Cai Y-Z, He P, Shu J-C, Cao W-Q, Yuan J. 2D MXenes: electromagnetic property for microwave absorption and electromagnetic interference shielding. Chemical Engineering Journal. 2019;359:1265-302.
10. Li T, Yao L, Liu Q, Gu J, Luo R, Li J, et al. Fluorine‐free synthesis of high‐purity Ti3C2Tx (T= OH, O) via alkali treatment. Angewandte Chemie International Edition. 2018;57(21):6115-9.
11. Peng C, Wei P, Chen X, Zhang Y, Zhu F, Cao Y, et al. A hydrothermal etching route to synthesis of 2D MXene (Ti3C2, Nb2C): Enhanced exfoliation and improved adsorption performance. Ceramics International. 2018;44(15):18886-93.
12. Bu F, Zagho MM, Ibrahim Y, Ma B, Elzatahry A, Zhao D. Porous MXenes: Synthesis, structures, and applications. Nano Today. 2020;30:100803.
13. Mashtalir O, Naguib M, Mochalin VN, Dall'Agnese Y, Heon M, Barsoum MW, et al. Intercalation and delamination of layered carbides and carbonitrides. MXenes: Jenny Stanford Publishing; 2023. p. 359-77.
14. Shuck CE, Sarycheva A, Anayee M, Levitt A, Zhu Y, Uzun S, et al. Scalable synthesis of Ti3C2Tx mxene. MXenes: Jenny Stanford Publishing; 2023. p. 539-60.
15. Chen H, Ma H, Li C. Host–guest intercalation chemistry in MXenes and its implications for practical applications. ACS nano. 2021;15(10):15502-37.
16. Kim Y-J, Kim SJ, Seo D, Chae Y, Anayee M, Lee Y, et al. Etching mechanism of monoatomic aluminum layers during MXene synthesis. Chemistry of Materials. 2021;33(16):6346-55.
17. Lim KRG, Shekhirev M, Wyatt BC, Anasori B, Gogotsi Y, Seh ZW. Fundamentals of MXene synthesis. Nature Synthesis. 2022;1(8):601-14.
18. Célérier S, Hurand S, Garnero C, Morisset S, Benchakar M, Habrioux A, et al. Hydration of Ti3C2T x MXene: An Interstratification Process with Major Implications on Physical Properties. Chemistry of Materials. 2018;31(2):454-61.
19. Kim SJ, Koh H-J, Ren CE, Kwon O, Maleski K, Cho S-Y, et al. Metallic Ti3C2T x MXene gas sensors with ultrahigh signal-to-noise ratio. ACS nano. 2018;12(2):986-93.
20. Koh H-J, Kim SJ, Maleski K, Cho S-Y, Kim Y-J, Ahn CW, et al. Enhanced selectivity of MXene gas sensors through metal ion intercalation: in situ X-ray diffraction study. Acs Sensors. 2019;4(5):1365-72.
21. Yuan W, Yang K, Peng H, Li F, Yin F. A flexible VOCs sensor based on a 3D Mxene framework with a high sensing performance. Journal of Materials Chemistry A. 2018;6(37):18116-24.
22. Zeynali M, Asgharizadeh S, Esfandyari-Kalejahi A. Mixed Termination of Ti3C2 MXene toward Better Sensing of Nucleobases: A Density Functional Theory Study. The Journal of Physical Chemistry C. 2024.
23. Li N, Jiang Y, Xiao Y, Meng B, Xing C, Zhang H, et al. A fully inkjet-printed transparent humidity sensor based on a Ti 3 C 2/Ag hybrid for touchless sensing of finger motion. Nanoscale. 2019;11(44):21522-31.
24. Lee E, VahidMohammadi A, Yoon YS, Beidaghi M, Kim D-J. Two-dimensional vanadium carbide MXene for gas sensors with ultrahigh sensitivity toward nonpolar gases. ACS sensors. 2019;4(6):1603-11.
25. Guo X, Ding Y, Kuang D, Wu Z, Sun X, Du B, et al. Enhanced ammonia sensing performance based on MXene-Ti3C2Tx multilayer nanoflakes functionalized by tungsten trioxide nanoparticles. Journal of Colloid and Interface Science. 2021;595:6-14.
26. Liu M, Wang Z, Song P, Yang Z, Wang Q. Flexible MXene/rGO/CuO hybrid aerogels for high performance acetone sensing at room temperature. Sensors and Actuators B: Chemical. 2021;340:129946.
27. Mazumder JT, Jha RK. Theoretical insights into gas sensing properties of MXene. Sensors and Actuators Reports. 2023:100174.
28. Parey V, Abraham BM, Mir SH, Singh JK. High-throughput screening of atomic defects in MXenes for CO2 capture, activation, and dissociation. ACS Applied Materials & Interfaces. 2021;13(30):35585-94.
29. Quesne MG, Roldan A, de Leeuw NH, Catlow CRA. Carbon dioxide and water co-adsorption on the low-index surfaces of TiC, VC, ZrC and NbC: a DFT study. Physical Chemistry Chemical Physics. 2019;21(20):10750-60.
30. Akhtar K, Khan SA, Khan SB, Asiri AM. Scanning electron microscopy: Principle and applications in nanomaterials characterization: Springer; 2018.
31. Epp J. X-ray diffraction (XRD) techniques for materials characterization. Materials characterization using nondestructive evaluation (NDE) methods: Elsevier; 2016. p. 81-124.
32. Andrade JD. X-ray photoelectron spectroscopy (XPS). Surface and Interfacial Aspects of Biomedical Polymers: Volume 1 Surface Chemistry and Physics. 1985:105-95.
33. Egerton RF. Physical principles of electron microscopy: Springer; 2005.
34. Williams DB, Carter CB, Williams DB, Carter CB. The transmission electron microscope: Springer; 1996.
35. Mohamed MA, Jaafar J, Ismail A, Othman M, Rahman M. Fourier transform infrared (FTIR) spectroscopy. Membrane characterization: Elsevier; 2017. p. 3-29.
36. Tyona M. A theoritical study on spin coating technique. Advances in materials Research. 2013;2(4):195.
37. Lee Y, Kim SJ, Kim Y-J, Lim Y, Chae Y, Lee B-J, et al. Oxidation-resistant titanium carbide MXene films. Journal of Materials Chemistry A. 2020;8(2):573-81.
38. Alhabeb M, Maleski K, Anasori B, Lelyukh P, Clark L, Sin S, et al. Guidelines for synthesis and processing of two-dimensional titanium carbide (Ti3C2T x MXene). Chemistry of Materials. 2017;29(18):7633-44.
39. Mathis TS, Maleski K, Goad A, Sarycheva A, Anayee M, Foucher AC, et al. Modified MAX phase synthesis for environmentally stable and highly conductive Ti3C2 MXene. ACS nano. 2021;15(4):6420-9.
40. Parker T, Zhang D, Bugallo D, Shevchuk K, Downes M, Valurouthu G, et al. Fourier-transform infrared spectral library of MXenes. Chemistry of Materials. 2024;36(17):8437-46.
41. Arif N, Gul S, Sohail M, Rizwan S, Iqbal M. Synthesis and characterization of layered Nb2C MXene/ZnS nanocomposites for highly selective electrochemical sensing of dopamine. Ceramics International. 2021;47(2):2388-96.
42. Nakamoto K. Infrared and Raman spectra of inorganic and coordination compounds, part B: applications in coordination, organometallic, and bioinorganic chemistry: John Wiley & Sons; 2009.
43. Lu Y, Li D, Liu F. Characterizing the chemical structure of Ti3C2Tx MXene by angle-resolved XPS combined with argon ion etching. Materials. 2022;15(1):307.
44. Persson I, Näslund L-Å, Halim J, Barsoum MW, Darakchieva V, Palisaitis J, et al. On the organization and thermal behavior of functional groups on Ti3C2 MXene surfaces in vacuum. 2D Materials. 2017;5(1):015002.
45. Lars-Åke N, Persson P. Å.; Rosen, J. X-ray Photoelectron Spectroscopy of Ti3AlC2, Ti3C2Tz, and TiC Provides Evidence for the Electrostatic Interaction between Laminated Layers in MAX-Phase Materials. J Phys Chem C. 2020;124:27732-42.
46. Xia QX, Fu J, Yun JM, Mane RS, Kim KH. High volumetric energy density annealed-MXene-nickel oxide/MXene asymmetric supercapacitor. RSC advances. 2017;7(18):11000-11.
47. Natu V, Benchakar M, Canaff C, Habrioux A, Celerier S, Barsoum MW. A critical analysis of the X-ray photoelectron spectra of Ti3C2Tz MXenes. Matter. 2021;4(4):1224-51.
48. Soomro RA, Zhang P, Fan B, Wei Y, Xu B. Progression in the oxidation stability of MXenes. Nano-Micro Letters. 2023;15(1):108.
49. Sang X, Xie Y, Lin M-W, Alhabeb M, Van Aken KL, Gogotsi Y, et al. Atomic defects in monolayer titanium carbide (Ti3C2T x) MXene. ACS nano. 2016;10(10):9193-200.
50. Nazemi H, Joseph A, Park J, Emadi A. Advanced micro-and nano-gas sensor technology: A review. Sensors. 2019;19(6):1285.
51. Yamazoe N, Shimanoe K. Fundamentals of semiconductor gas sensors. Semiconductor Gas Sensors: Elsevier; 2020. p. 3-38.
52. Junkaew A, Arroyave R. Enhancement of the selectivity of MXenes (M 2 C, M= Ti, V, Nb, Mo) via oxygen-functionalization: promising materials for gas-sensing and-separation. Physical Chemistry Chemical Physics. 2018;20(9):6073-82.
53. Mishra SB, Nanda B. Facet dependent catalytic activities of anatase TiO2 for CO2 adsorption and conversion. Applied Surface Science. 2020;531:147330.
54. Levenspiel O. Chemical reaction engineering: John wiley & sons; 1998.
55. Fogler HS. Essentials of chemical reaction engineering: essenti chemica reactio engi: Pearson education; 2010.
56. https://www.buildenvi.com/zhuanti/abc/skq/150424a3