Bhunia Amit Kumar, Mahata Bidesh, Mandal Biswajit, Guha Prasanta Kumar, Saha Satyajit
Department of Physics, Government General Degree College Gopiballavpur-II, Jhargram 721517, India.
School of Nano Science and Technology, Indian Institute of Technology Kharagpur, Paschim Medinipur 721302, India.
Nanotechnology. 2024 Aug 27;35(45). doi: 10.1088/1361-6528/ad6e8b.
Herein, we fabricated nanoscale 2D CeOsheet structure to develop a stable resistive gas sensor for detection of low concentration (ppm) level formaldehyde vapors. The fabricated CeOnanosheets (NSs) showed an optical band gap of 3.53 eV and cubic fluorite crystal structure with enriched defect states. The formation of 2D NSs with well crystalline phases is clearly observed from high-resolution transmission electron microscope (HRTEM) images. The NSs have been shown tremendous blue-green emission related to large oxygen defects. A VOC sensing device based on fabricated two-dimensional NSs has been developed for the sensing of different VOCs. The device showed better sensing for formaldehyde compared with other VOCs (2-propanol, methanol, ethanol, and toluene). The response was found to be 4.35, with the response and recovery time of 71 s and 310 s, respectively. The device showed an increment of the recovery time (71 s to 100 s) with the decrement of the formaldehyde ppm (100 ppm to 20 ppm). Theoretical fittings provided the detection limit of formaldehyde ≈8.86 ± 0.45 ppm with sensitivity of 0.56 ± 0.05 ppm. The sensor device showed good reproducibility with excellent stability over the study period of 135 d, with a deviation of 1.8% for 100 ppm formaldehyde. The average size of the NSs (≈24 nm) calculated from HRTEM observation showed lower value than the calculated Debye length (≈44 nm) of the charge accumulation during VOCs sensing. Different defect states, interstitial and surface states in the CeONSs as observed from the Raman spectrum and emission spectrum are responsible for the formaldehyde sensing. This work offers an insight into 2D semiconductor-based oxide material for highly sensitive and stable formaldehyde sensors.
在此，我们制备了纳米级二维CeO片状结构，以开发一种用于检测低浓度（ppm级）甲醛蒸气的稳定电阻式气体传感器。制备的CeO纳米片（NSs）显示出3.53 eV的光学带隙和具有丰富缺陷态的立方萤石晶体结构。从高分辨率透射电子显微镜（HRTEM）图像中可以清楚地观察到具有良好晶相的二维NSs的形成。NSs表现出与大量氧缺陷相关的强烈蓝绿色发射。基于制备的二维NSs开发了一种用于检测不同挥发性有机化合物（VOCs）的传感装置。与其他VOCs（2-丙醇、甲醇、乙醇和甲苯）相比，该装置对甲醛表现出更好的传感性能。响应值为4.35，响应时间和恢复时间分别为71 s和310 s。随着甲醛ppm值从100 ppm降至20 ppm，该装置的恢复时间有所增加（从71 s增加到100 s）。理论拟合得出甲醛的检测限约为8.86±0.45 ppm，灵敏度为0.56±0.05 ppm。该传感器装置在135天的研究期内具有良好的重现性和出色的稳定性，对于100 ppm甲醛的偏差为1.8%。根据HRTEM观察计算得出的NSs平均尺寸（≈24 nm）低于VOCs传感过程中电荷积累的计算德拜长度（≈44 nm）。从拉曼光谱和发射光谱观察到的CeONSs中的不同缺陷态、间隙态和表面态是甲醛传感的原因。这项工作为基于二维半导体的氧化物材料用于高灵敏度和稳定的甲醛传感器提供了见解。
