Annealing effect on microstructure of ZnO nano-particulate films and VOC gas sensing property

Abstract

We synthesized ZnO nano-particulate films by a sol–gel method and evaluated their gas sensing properties. A ZnO colloidal solution of 5.6 nm sized nanocrystals was prepared from zinc acetate in n-propanol and dip-coated on silica glass substrates. The as-deposited ZnO film consisted of 30 nm grains. Annealing the films resulted in a growth of the particles, which was confirmed by scanning probe microscopy and UV–Vis spectrometry. The ZnO film annealed at 400°C worked well as a gas sensor device for volatile organic compounds (VOC) gases. The sensitivity was the best in the case of ethanol gas at 350°C. The sensing performances decreased by annealing at higher temperatures due to the coalescence of the ZnO particles.