Lattice doped Zn–SnO2 nanospheres: A systematic exploration of dopant ion effects on structural, optical, and enhanced gas sensing properties

• Published in: Applied surface science 2015-12, Vol.357, p.1511-1521
• Main Authors: Baraneedharan, P., Imran Hussain, S., Dinesh, V.P., Siva, C., Biji, P., Sivakumar, M.
• Format: Article
• Language: English
• Subjects: Diffraction; Environmental monitoring; Gas sensors; Hydrothermal; Lattice doping; Lattices; Nanospheres; Nitrogen dioxide; Resistive sensors; Tin dioxide; Tin oxides; Zinc
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.09.257

•A simple, novel and surfactant free hydrothermal route to prepare SnO2 nanospheres.•A systematic investigation of growth mechanism with the assist of time dependent HR-TEM images.•Incorporation of Zn ions into SnO2 lattices clearly elucidated with XRD and XPS spectrums.•Three fold time increased response in Zn–SnO2 nanospheres when compared to undoped SnO2. A surfactant-free one step hydrothermal method is reported to synthesize zinc (Zn2+) doped SnO2 nanospheres. The structural analysis of X-ray diffraction confirms the tetragonal crystal system of the material with superior crystalline nature. The shift in diffraction peak, variation in lattice constant and disparity in particle size confirm the incorporation of Zn2+ ions to the Sn host lattices. The lattice doped structure, the disparity in morphology, size and shape by the addition of Zn2+ ions are evident from X-ray photoelectron spectroscopic and electron microscopic analysis. Significant changes in the absorption edge and the band gap with increased doping concentration were observed in UV–vis absorption spectral analysis. The formation of acceptor energy levels with the incorporation of Zn2+ ions has a significant effect on the electrical conductivity of SnO2 nanospheres. Comparative tests for gas sensors based on Zn doped SnO2 nanospheres and SnO2 nanospheres clearly show that the former exhibited excellent NO2 sensing performance. The responses of Zn2+ ions incorporated SnO2 nanospheres sensor were increased 3 fold at trace level NO2 gas concentrations ranging from 1 to 5ppm. The excellent sensitivity, selectivity and fast response make the Zn2+ doped SnO2 nanospheres ideal for NO2 sensing.