Lattice doped Zn-SnO <inf>2</inf> nanospheres: A systematic exploration of dopant ion effects on structural, optical, and enhanced gas sensing properties

A surfactant-free one step hydrothermal method is reported to synthesize zinc (Zn 2+ ) doped SnO 2 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 Zn 2+ ions to the Sn host lattices. The lattice doped structure, the disparity in morphology, size and shape by the addition of Zn 2+ 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 Zn 2+ ions has a significant effect on the electrical conductivity of SnO 2 nanospheres. Comparative tests for gas sensors based on Zn doped SnO 2 nanospheres and SnO 2 nanospheres clearly show that the former exhibited excellent NO 2 sensing performance. The responses of Zn 2+ ions incorporated SnO 2 nanospheres sensor were increased 3 fold at trace level NO 2 gas concentrations ranging from 1 to 5 ppm. The excellent sensitivity, selectivity and fast response make the Zn 2+ doped SnO 2 nanospheres ideal for NO 2 sensing.