Gas Sensor Application of Chemically Synthesized Nanomaterials

Abstract

In this work, nickel oxide (NiO) thin films was deposited via simplistic and economical successive ionic layer adsorption and reaction (SILAR) method by using nickel chloride and urea as precursor. XRD showing that (200) crystal orientation is preferred in the films with crystallite size of ~44 nm. Formation of mixed platelets-type morphology with number of gas adsorption sites was confirmed by using FESEM and supported by SEAD pattern. Various chemical bands present in NiO were identified by Raman and EDX investigation illustrates the presence of Ni and O elements in the SILAR-deposited NiO film. Surface-area and poresize of NiO powder scratched from the film were 57.84 m2g-1 and 33.56 nm, respectively. The size of NiO 4-8 nm was confirmed by TEM and supported by HRTEM.Chemo-resistive performance of NiO thin films was carried out towards hazardous and explosive gases such as NH3, CH3OH, C2H5OH, LPG and NO2 as a function of working temperature and gas concentration. Amongst these gases, NiO sensor film exhibits higher sensitivity of 72% to 5000 ppm of LPG at 180°C. LPG concentration effect on gas sensitivity is investigated as higher the concentration more is response due to more surface area coverage. Also, the synergetic interaction between LPG molecules and NiO thin film nanocrystallites was studied and explored. Zinc oxide (ZnO) nanograins were grown on a glass substrate by simple and rapid chemical bath deposition method with zinc nitrate and urea as precursors at low pH condition (~9) without adding any complexing agent. The structural analysis, morphology and surface chemistry were confirmed from the XRD, EDX, Raman spectroscopy, X-ray photoelectron spectroscopy, BET analysis, FE-SEM and TEM imaging. Chemiresitive selectivity and sensitivity of ZnO film sensor toward NO2 gas was found better than other target gases like methanol, ethanol, hydrogen sulphide, chlorine and nitrogen dioxide. Remarkable to high sensitivities from 176% to 610% towards NO2 gas have been obtained for wide concentration range betwe