Structural characterization and gas sensing applications of ultrafine ZrO2 nanospheres using low temperature solution route

Abstract

Monophasic ZrO2 nanoparticles were successfully prepared by using low temperature solution route. As-prepared nanoparticles were characterized by different techniques like XRD, SEM, TEM, BET and UV–Visible studies. X-ray diffraction analysis revealed the crystalline tetragonal phase of ZrO2. Transmission electron microscopic studies show the formation of 15 nm sized spherical particles of zirconia. The surface morphological studies were established by Scanning Electron Microscopy. UV–Visible diffused reflectance spectroscopy studies give the optical band gap of 4.9 eV for the synthesized nanoparticles. BET surface area studies revealed the high surface area of 128 m2/g. Enhanced gas sensing property was revealed by the ZrO2 nanoparticles over carbon monoxide at 50 ppm concentration and at a minimal operating temperature of 240 °C. The good sensing properties can indeed be ascribed to the large oxygen surface vacancies available and the high surface area possessed by the ZrO2 nanoparticles which are favorable for both the transport of gas molecules and sensing reactions to occur as was deduced from the sensing mechanism.