BITS Faculty Publications
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Item Realization of ppb-level acetone detection using noble metals (Au, Pd, Pt) nanoparticles loaded GO FET sensors with simultaneous back-gate effect(Elsevier, 2022-02) Hazra, ArnabIn the current study, graphene oxide (GO), uniformly loaded with different noble metal nanoparticles (Au, Pd and Pt) were synthesized by spray coating technique and implemented in field effect transistor (FET) sensors. The morphology, structure, composition and electronic properties of the synthesized materials were characterized. The sensing results indicated that the incorporation of noble metals can greatly enhance the VOC sensing properties of a few layers of GO by using their chemical and electrical sensitization effect. At optimized gate potential, GO FET exhibited outstanding sensing properties at low operating temperature i.e. 50 °C. Specifically, the FET sensor based on Pd loaded GO exhibited the highest response, quickest response/recovery (37 s/91 s) characteristics, best selectivity and low operating temperature towards low concentration of acetone. Almost five times higher sensitivity towards acetone (400 ppb) was achieved in Pd/GO as compared to the pure GO channel nanoparticles under a suitable back gate bias.Item Synthesis and characterization of hybrid NiO/CeO2 p-n heterojunction nanofibers for room temperature ammonia sensing application(Elsevier, 2024-08) Hazra, ArnabThe development of room temperature chemiresistive NH3 gas sensors with superior selectivity and stability is always an uphill task to solve. This work describes the synthesis and characterization of NiO/CeO2 p-n heterojunction nanofiber assembly using a facile electrospinning method. Systematic studies are conducted using SEM, XRD, XPS, and TEM to examine the microstructure and morphology. The electro spun nanofibers offer high surface area of NiO/CeO2 p-n heterojunction composite sensor with an average fiber diameter of ∼125 ± 20 nm, regulated morphology, and interconnectivity through junction formation. Under ambient temperature, the sensing performance for 10–100 ppm NH3 gas is investigated. The increased specific surface areas, formations of multiple NiO/CeO2 bridging point contacts are responsible for the improved gas sensitivity. Experiments reveal that NiO/CeO2 hybrid nanofiber sensor outperforms the pure NiO NF sensor for NH3 sensing, in addition to superior selectivity, good stability and quick response/recovery time. Gas sensors based on NiO/CeO2 are anticipated to become a viable option for the detection of ammonia in breathed gas of sufferers with gastrointestinal or renal disorders in the future due to their flexibility, room temperature operation, and good reaction to ammonia.Item Capacitive gas and vapor sensors using nanomaterials(Springer, 2018-01) Hazra, ArnabAn immense number of sensors has been reported in the literature employing various methods for the detection of different gases and vapors. This article summarizes those sensors whose sensing layer is made up of nanostructured materials and a change in capacitance value of device is the key parameter for detecting a gas or vapor. Now-a-days, capacitive sensors are emerging as they consume less power, operate well at room temperature and show decent response and recovery time. The sensing principles, configurations, mechanisms and performances of capacitive sensors based on different nanostructures are summarized and discussed in the current article. Emerging carbon based nanomaterials like carbon nanotube and graphene are also highlighted for capacitive mode detection of gases and vapors. Finally, an outlook of primary challenges in this field are identified and discussed at the end of the review.