Understanding the ethanol and acetone sensing behaviour of CuO thin films through elements of gas diffusion theory

Effects of withdrawal speed on the structural, morphological, electrical, and optical properties of CuO thin films synthesized by dip-coating for CO2 gas sensing

“…3,4 Due to its abundance in earth crust, environmentally benign nature as well as tailorable electro-optical properties, recently CuO attracts tremendous attention in the thin-film technology to explore its potential device application such as solar cells, 5 electrochemical devices, 6 and more importantly for gas sensors. 1,7,8,9 In the case of gas sensing, CuO thin film-based sensors are particularly alluring due to their chemical stability, large water contact angle (>90 0 ), high sensitivity, faster response time, lower operating temperature as well as proven ability to detect diverse gases such as NO2, H2, CO, CO2, etc. 7,8,10 Carbon dioxide (CO has been extensively used as a refrigerant in fire extinguishers, life jackets also escalated life rafts, plastic, food packaging as well as in carbonated drinks, etc.…”

“…1,7,8,9 In the case of gas sensing, CuO thin film-based sensors are particularly alluring due to their chemical stability, large water contact angle (>90 0 ), high sensitivity, faster response time, lower operating temperature as well as proven ability to detect diverse gases such as NO2, H2, CO, CO2, etc. 7,8,10 Carbon dioxide (CO has been extensively used as a refrigerant in fire extinguishers, life jackets also escalated life rafts, plastic, food packaging as well as in carbonated drinks, etc. 9 Therefore, reliable, selective, and fast detection of carbon dioxide gas appears to be the strict necessity for various industrial purposes.…”

“…5 However, most of the CO sensing devices are bulky, suffer from short-life time, expensive maintenance as well as their vulnerability to interference gases. 7 Therefore, for CO sensing applications, CuO thin films are the most widely studied because of its attractive features mentioned above. However, the gas sensing mechanism is also related to various structural parameters (crystallite size and dislocation densities), the thickness of the film as well as its morphological properties.…”

“…CuO thin films can be grown by different deposition techniques such as thermal oxidation, 12 thermal evaporation, 13 filtered cathodic vacuum arc, 14 pulsed laser deposition, 15 Sputtering, 6 electro-spinning, 16 microwave hydrothermal synthesis, 17 the hydrothermal method, 18 spray pyrolysis, 19 and diverse sol-gel based synthesis techniques 7,8,20,21 etc. Among them, the sol-gel dipcoating technique is the simplest and most economical one to deposit thin film under a non-vacuum environment with good control over growth parameters preferably at low processing temperatures 22,23 .…”

“…al. 7 reported spin-coated CuO thin film with varying thickness for detecting volatile organic compounds (VOCs) operated at 200 -300 °C and obtained maximum response for alcohol and acetone at 300 °C for 240 nm thick CuO films. Chapelle et al 26 reported RF-sputtered CuO/CuFe2O4 thin films and achieved the best CO2 sensing response at an optimal operating temperature of 250 °C.…”