Effect of Calcination Temperature on ${\hbox {NO}}_{2}$ Sensing Properties for Quantum Size ZnO Crystals

Quantum size ZnO crystals have been synthesized successfully by a room temperature sol-gel process using oleic acid (OA) as capping agent to control the particle size. The particle size and structure of ZnO nanocrystals have been charactirized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Raman spectra analysis methods. The sensor based on ZnO powder calcined at 400 °C for 1 h exhibits the highest response of 280 to NO₂ and the selectivity to CO and CH₄ at the same concentration reaches 31 and 49 at operating temperature of 290 °C. The effect of calcination temperature on the performance of gas sensing has also been studied.