Microstructure and gas sensing properties of the ZnO thick film treated by hydrothermal method

Nanostructured films of tetrapod-shaped ZnO (T-ZnO) were fabricated by a combination of screen-printing technology and hydrothermal treatment process. The morphologies and crystal structures of the films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The stability was analyzed by impedance spectroscopy. The results showed that ZnO nanostructures were induced on the surface of the films through the hydrothermal treatment process. The nanostructures were composed of nanowalls with thickness of about 15 nm. The resistance–temperature characteristic and the response to VOCs (benzene, toluene, methanol and ethanol) revealed that the hydrothermal treatment process could effectively control the surface morphologies and microstructures of the films, keep the nanocharacteristic of the films, enhance the response of the sensors and improve the stability of the sensors.