Lattice doped Zn-SnO2 nanospheres: A systematic investigation of dopant ion effects on structural, optical, and improved NO2 sensing properties

P. Baraneedharan , C. Siva , M. Sivakumar

Nanoscience and Technology
Anna University- BIT campus
Tiruchirappalli- 620024
Tamilnadu, India

A surfactant-free one step hydrothermal method is reported to synthesize zinc (Zn2+) doped SnO2 nanospheres. The structural analysis from X- ray diffraction confirms the prepared nanospheres correspond to tetragonal crystal system 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. This incorporation is also evident from   X-ray photoelectron spectroscopy analysis. The disparity in morphology, size and shape by the addition of Zn2+ ions is evident from electron microscope images.  Significant changes in the absorption edge and the band gap with increased doping concentration were observed using UV-Vis absorption spectrometer. The formation of acceptor energy levels with the incorporation of Zn2+ ions has significant effect in the electrical conductivity of SnO2 nanospheres. Comparative tests for gas sensors based on Zn doped SnO2 nanospheres and SnO2 nanospheres clearly showed that the former exhibited excellent NO2 sensing performance. The responses of Zn2+ ions incorporated SnO2 nanospheres sensor were increased 3 fold at NO2 gas concentrations ranging from 1-5 ppm.  The excellent sensitivity, selectivity and fast response makes the Zn2+ doped SnO2 nanospheres ideal for NO2 sensing.