Synthesis and characterization of Gd-doped SnO2 nanostructures and their enhanced gas sensing properties

Abstract

In the present work, we report the influence of Gd-doping on structural, optical and gas sensing properties of SnO2 nanoparticles. X-ray diffraction (XRD) and Raman spectroscopy studies confirmed formation of tetragonal rutile type structure of both undoped and Gd-doped SnO2 nanoparticles. The crystallite size has been found to decrease with increase in dopant concentration which was confirmed from XRD and TEM techniques. It has been observed that Raman surface modes are directly related to the surface area of nanoparticles. Photoluminescence (PL) spectroscopy confirmed large number of oxygen vacancies in 3% Gd-doped SnO2 nanoparticles. It has been observed that 3% doped sensor displayed exceptionally large sensor response towards ethanol which is about 27 times larger than that of undoped sensor. The optimum operating temperature of doped sensors has reduced as compared to undoped sensor. The enhanced sensor response of Gd-doped nanoparticles has been attributed to small crystallite size, large number of oxygen vacancies, high surface basicity and increased contribution of Raman surface modes. Moreover, it has been observed that 3% Gd doped SnO2 nanoparticle sensor is highly selective towards ethanol.