Tin dioxide nanoparticles: Reverse micellar synthesis and gas sensing properties

Abstract

Tin dioxide (SnO2) nanoparticles have been synthesized by reverse micellar route using cetyltrimethyl ammoniumbromide (CTAB) as the surfactant. Monophasic tin dioxide (SnO2) was obtained using NaOH as the precipitation agent at 60 °C, however, when liquor NH3 was used as precipitating agent then crystalline SnO2 nanoparticles are obtained at 500 °C. SnO2 prepared using NaOH show crystallite size of 4 and 12 nm after heating at 60 and 500 °C respectively using X-ray line broadening studies. Transmission electron microscopy (TEM) studies show agglomerated particles of sizes 70 and 150 nm, respectively. The grain size was found to be 6–8 nm after heating the precursor obtained (using liquor NH3) at 500 °C by X-ray line broadening and the TEM studies. Dynamic light-scattering (DLS) studies show the aggregates of SnO2 nanoparticles with uniform size distribution. Mössbauer studies show an increase of s-electron density at the Sn sites compared to bulk SnO2 and a finite quadrupole splitting indicative of lowering of symmetry around tin atoms. The gas sensing characteristics have also been investigated using n-butane which show high sensitivity and fast recovery time.