Tetragonal BaTiO3 spheroids synthesized by a facile hydrothermal route using Tween 80 were observed to be polydispersed with a diameter in the range of ∼15-75 nm. Thereon, BaTiO3 spheroids were decorated with different percentages of Ag@CuO by wet impregnation, and their affinity toward carbon dioxide (CO2) gas when employed as sensitive layers in a microsensor was investigated. The results revealed that the metal nanocomposite-based sensor had an exceptional stability and sensitivity toward CO2 gas (6-fold higher response), with appreciable response and recovery times (<10 s) and higher repeatability (98%) and accuracy (96%) at a low operating temperature of 120 °C, compared to those of pure BaTiO3 and CuO. Such improved gas-sensing performances even at a very low concentration (∼700 ppm) is attributable to both the chemical and electrical contributions of Ag@CuO forming intermittent nanointerfaces with BaTiO3 spheroids, exhibiting unique structural stability. The CO2-sensing mechanism of CuO/BaTiO3 nanocomposite was studied by the diffuse reflectance infrared Fourier transform spectroscopy technique that established the reaction of CO2 with BaO and CuO to form the respective carbonate species that is correlated with the change in material resistance consequently monitored as sensor response.

Efficient Heterostructures of Ag@CuO/BaTiO3 for Low-Temperature CO2 Gas Detection: Assessing the Role of Nanointerfaces during Sensing by Operando DRIFTS Technique.

Al-doped ZnO (AZO) samples were prepared using a modified sol–gel route and charaterized by means of trasmission electron microscopy, x-ray diffraction and photoluminescence analysis. Resistive planar devices based on thick films of AZO deposited on interdigitated alumina substrates were fabricated and investigated as UV light activated CO sensors. CO sensing tests were performed in both dark and illumination condition by exposing the samples to UV radiation (λ = 400 nm).Under UV light, Al-doped ZnO gas sensors operated at lower temperature than in dark. Furthermore, by photoactivation we also promoted CO sensitivity and made signal recovery of AZO sensors faster. Results demonstrate that Al-doped ZnO might be a promising sensing material for the detection of CO under UV illumination.

https://iopscience.iop.org/article/10.1088/0022-3727/49/13/135502/pdf

Gas sensing properties of Al-doped ZnO for UV-activated CO detection

UV light activated gas sensor for NO2 detection

Thin films of BaTiO3-CuO doped with Ag have been evaluated for their carbon dioxide sensing characteristics. The effect of various parameters, such as Ag doping, annealing conditions, film thickness, electrode dimensions, and operating temperature on sensitivity has been explored. The thin films in the range of 250 nm, with 1% Ag doping and no post-deposition annealing, display the best sensitivity at an optimum operating temperature of 250 °C. We correlate sensitivity with material characteristics as determined by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, and electron probe microscopic analysis. Sensitivity to CO2 increases with the reduction in electrode dimensions, with 500 nm electrodes giving the best sensitivity of 19% for 350 ppm and 80% for 1000 ppm of CO2. The sensor shows very low cross sensitivity to CO, NO2, and SO2.

Optimization of RF Sputtered Ag-Doped BaTiO 3 -CuO Mixed Oxide Thin Film as Carbon Dioxide Sensor for Environmental Pollution Monitoring Application

Globally recognized for its role as an occupational hazard, carbon dioxide (CO2) detection and monitoring is essential in agriculture, chemical manufacturing, and healthcare/clinical-oriented applications. Although, optical and chemical gas sensors are available commercially, current gas sensing technologies involving selective monitoring of CO2 at lower detection limits specifically for industrial conditions still remains a formidable challenge. Herein, we present a simple strategy for highly selective CO2 detection using an inexpensive transducer platform based on reversible chemisorbed carbonation between CO2 and CaO-BaTiO3 heterostructures. Microsensors showed an optimum sensitivity of 65% toward 1000 ppm of CO2 gas and superior selectivity when operated at 160 °C. Such a remarkable sensing performance originates from the discretely created n-n nanointerfaces and conveniently actualized staggered energy band positions that promote favorable charge transfer upon exposure to CO2 gas molecules even at pa...

S.M. Yakout

Papers

Electrical Conductivity and Sensitive Characteristics of Ag-Added BaTiO3-CuO Mixed Oxide for CO2 Gas Sensing