Abstract
Metal oxide resistive gas sensors suffer from poor selectivity that restricts their practical applicability. Conventional sensor arrays are used to improve selectivity which increased the system complexity. Here, we have proposed a novel NiO/ZnO-based p–n junction single-diode device for selective sensing of several volatile organic compounds (VOCs) simultaneously by tuning bias voltage. The operating voltage was varied between 3 and 5 volts to achieve selective sensing of 2-propanol (19.1 times for 95 ppm with response and recovery times of 70 s and 55 s respectively‚ at 3 volts), toluene (20.1 times for 95 ppm with response and recovery times of 100 s and 60 s respectively, at 4 volts), and formaldehyde (11.2 times for 95 ppm with response and recovery times of 88 s and 54 s respectively, at 5 volts). A probable mechanism of the tunable selectivity with operating bias voltage due to increase in surface carriers with increasing voltage was hence put forth. Thus, this device may play an important role to develop future selective multiple VOC sensor thereby replacing standard sensor arrays.
Highlights
Volatile organic compounds (VOCs) are used for the development of several industrial products[1]
Detection of VOCs plays an important role in agriculture as well, e.g., ethylene and Correspondence: Samit Kumar Ray or Prasanta Kumar Guha 1Department of Electronics & Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721302, India 2Department of Electrical Engineering, National Institute of Technology, Agartala 99046, India Full list of author information is available at the end of the article
Sensing device characterization The phase and crystalinity of the device were performed by X-ray diffraction (XRD; Ultima III, Rigaku X-ray diffractometer; Cu Kα radiation, λ = 1.5404 Å)
Summary
Volatile organic compounds (VOCs) are used for the development of several industrial products[1]. VOCs are toxic and can cause many short-term as well as long-term health problems if inhaled in excess amount[2,3,4,5]. There are several applications where selective detection of VOCs is important. Detection of VOCs plays an important role in agriculture as well, e.g., ethylene and esters are released with ripening of fruits (e.g., banana). Level of such VOCs can give information of ripening stage of fruits. It is important to detect VOCs selectively[7,8]
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