High performances room temperature NO2 gas sensor based on ZnO nanoparticles with oxygen vacancies prepared by auto combustion method

Abstract

Pure zinc oxide was prepared by an auto-combustion method and oxygen vacancies were created by means of a thermally activated process as it is based on a vacuum treatment. XRD, XPS and SEM characterizations were used to determine the structure and morphology of pure and treated ZnO1 − X with x equal to 0, 0.05 and 0.10. Optical measurement was investigated in the UV-Visible range and indicated that oxygen vacancies enhance absorption in the visible range. Gas sensors were prepared by spraying the solution of ZnO1 − X nanoparticles on alumina substrates with pre-deposited gold interdigitated electrodes. The fabricated sensors exhibited exceptional sensing responses to 0.5 ppm of NO2 at room temperature and under white light illumination. The sensing tests outline an enhancement in sensors performances due to the presence of oxygen vacancies. The best response was 76, with 1.5 min and 2.7 min as response and recovery times respectively, obtained with sensor based on ZnO0.90 nanoparticles having the higher oxygen vacancy concentration, confirmed by XPS measurements and the lowest grain size and higher absorption in the visible range.