Vishwakarma Ankit Kumar, Sharma Ajaya Kumar, Verma Arpit, Yadav B C, Yadava Lallan
Department of Physics, Deen Dayal Upadhyaya Gorakhpur University Gorakhpur U.P. 273009 India
Nanomaterials and Sensors Research Laboratory, Department of Physics, Babasaheb Bhimrao Ambedkar University Lucknow-226025 U.P. India.
RSC Adv. 2024 Dec 3;14(51):38302-38310. doi: 10.1039/d4ra05824k. eCollection 2024 Nov 25.
In this article, the sensing behaviors of undoped titanium dioxide (TiO) and CdS-doped TiO (CdS-TiO) thick films are discussed. Sensing pastes of 2 wt% CdS-TiO and undoped TiO were prepared in the laboratory and used to fabricate thick film gas sensors on an alumina substrate. The crystal structures of TiO and CdS-TiO samples were characterized by XRD and atomic force microscopy (AFM). The results indicated that the grain size and RMS roughness parameter were reduced by adding CdS contents. The sensing behaviors of the fabricated devices were studied at varying concentrations (0-5000 ppm) of different hydrocarbon gases, such as LPG, methanol, ethanol, toluene, and benzene, in ambient air at 300 K. The effect of humidity levels on the sensing properties of the sensors was also investigated. The sensor response value of CdS-TiO for benzene was found to be 2.25 times higher than that of TiO-based sensing devices. Thus, CdS doping significantly enhanced the response and recovery times of the sensor. The TiO film exhibited response and recovery times of 65 s and 180 s, respectively. In contrast, when doped with CdS, the response times were reduced to 15 s and 103 s, respectively, when exposed to benzene at a concentration of 5000 ppm at 300 K. The sensing mechanism has been discussed and the experimental results were validated using a model based on the Frenkel-Poole theory of electronic emission and catalytic oxidation. The obtained results demonstrate that TiO structures doped with low concentrations of CdS exhibit superior sensitivity and selectivity to benzene gas under low humidity levels at room temperature (300 K).
在本文中，讨论了未掺杂二氧化钛（TiO）和硫化镉掺杂二氧化钛（CdS-TiO）厚膜的传感行为。在实验室中制备了2 wt% CdS-TiO和未掺杂TiO的传感浆料，并用于在氧化铝基板上制造厚膜气体传感器。通过X射线衍射（XRD）和原子力显微镜（AFM）对TiO和CdS-TiO样品的晶体结构进行了表征。结果表明，添加CdS含量会降低晶粒尺寸和均方根粗糙度参数。在300 K的环境空气中，研究了所制造器件在不同浓度（0-5000 ppm）的不同烃类气体（如液化石油气、甲醇、乙醇、甲苯和苯）下的传感行为。还研究了湿度水平对传感器传感性能的影响。发现CdS-TiO对苯的传感器响应值比基于TiO的传感器件高2.25倍。因此，CdS掺杂显著提高了传感器的响应和恢复时间。TiO薄膜的响应和恢复时间分别为65 s和180 s。相比之下，当掺杂CdS时，在300 K下暴露于浓度为5000 ppm的苯时，响应时间分别降至15 s和103 s。讨论了传感机制，并使用基于电子发射和催化氧化的弗伦克尔-普尔理论的模型对实验结果进行了验证。所得结果表明，在室温（300 K）低湿度水平下，低浓度CdS掺杂的TiO结构对苯气体表现出优异的灵敏度和选择性。
