A high-performance n-butanol gas sensor based on ZnO nanoparticles synthesized by a low-temperature solvothermal route

Abstract

ZnO nanoparticles with high crystallinity and several nanometers in size were synthesized by a low-temperature solvothermal route from zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O), potassium hydroxide (KOH) and methanol (CH₃OH). The structural and the morphological characterizations of the ZnO nanoparticles were performed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N₂-sorption isotherms. The obtained nanoparticles are highly crystalline wurtzite-type ZnO with a uniform near-spherical shape and an average particle size estimated to be 8.4 ± 1.3 nm. Such a small particle size and slight agglomeration are attributed to the use of methanol, which acts as both a solvent and an inhibitor of growth and agglomeration. The as-synthesized ZnO nanoparticles were directly used as a gas sensing material toward n-butanol gas. Such a designed sensor device exhibits several advantages such as a high and fast response, short recovery time, and good stability toward n-butanol gas. At the optimal operating temperature (320 °C), its gas response toward 500 ppm n-butanol is 805 and the response and recovery times are 22 and 6 seconds, respectively.