Chemisorbed CO₂ on the surface of Co-SnO₂ characterization and room temperature gas sensor

7^th International Conference on Smart Materials and Sustainable Technologies

April 08-09, 2019 | Toronto, Canada

Mohamed A Basyooni, Mohamed Shaban and Gamal F Attia

Nanyang TechnologicalUniversity, Singapore
University of Konya NecmettinErbakan, Turkey
Beni- Suef University, Egypt
National Research Instituteof Astronomy and Geophysics,Egypt

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

Pure and Cobalt-doped Tin oxide (SnO₂ and SnO₂:Co) thin films of varying thickness were successfully fabricated by the sol-gel spin coating technique. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effect of a number of layers on the structural and optical properties of SnO₂ and SnO₂: Co films were studied. The crystallite size of the pure SnO2 films increased from 7.7 to 31.1nm by increasing the number of layers from 12 to 24. The crystallinity of the film enhanced with increasing the annealing temperature from 400oC to 500oC. However, it reduced by incorporating Co atoms. The transmittance and the optical band gap of the SnO₂ film decreased by increasing the number of layers or after Co doping. The 8% Co-doped film shows relatively higher sensitivity for CO₂ gas at room temperature (RT) compared to un-doped SnO₂ film of increase of respect to CO₂ concentration is 0.116/sccm for Co-doped SnO₂. In this study, the carbon dioxide gas acted as an oxidizing agent that caused the increase in the electrical resistance of the sensor signified by the increase in voltage reading. Carbon dioxide sensing mechanism involves its disintegration into CO- and O- .These species are adsorbed on the surface of the thin film. The negative charge trapped in these oxygen species caused an upward band bending on the SnO₂ nanomaterial thus increasing its resistance compared to the flat band situation before CO₂ gas exposure. The response and recovery times increased as the CO2 concentration increased. The obtained results possibility of controlling the filmâ??s physical properties for sensing and optoelectronic applications.

Biography :

E-mail: mohamed.basyooni@nriag.sci.eg