Polypeptide-assisted hydrothermal synthesis of ZnO for room temperature NO2 gas sensor under UV illumination.

• The morphology of ZnO materials were regulated with polypeptides assisted. • The ZnO/polypeptides materials have good NO 2 gas-sensing performances at room temperature under UV activated. • The ZnO/polypeptides-based sensor also has short response time and good linearity towards NO 2. In this work, nanoflowers-like, nanoneedles-like ZnO and ZnO nanorods have been successfully synthesized by polypeptide-assisted hydrothermal routes. The nanostructures and morphologies of the ZnO crystals were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and it was shown that the additive of polypeptides could control the morphologies. The gas sensing properties of NO 2 have been investigated with the three ZnO materials, which showed that the ZnO nanorods-based sensor exhibits the highest response under 365 nm UV illumination at room temperature. Gas sensing results, towards NO 2 at a range of gas concentrations (10–25 ppm), also indicated it had good linearity and repeatability. [ABSTRACT FROM AUTHOR]