High performance Cr doped ZnO by UV for NH3 gas sensor

Abstract

In this work, Cr doped ZnO nanoparticles were synthesized by a hydrothermal method. Ammonia gas (NH3) sensing was tested under UV illumination at room temperature. The irradiation returned the sensor after detecting the NH3 molecules back to their initial states. More importantly, it created the electrons needed to ionize the oxygen molecules absorbed on the surface of the Cr:ZnO nanoparticles. This increase is necessary for the creation of more active surface sites which are necessary for the detection of the NH3 molecular in air. It was found that the increase in the output of doped ZnO nanoparticles sensor is due both to the Cr doping and to the UV irradiation. For a NH3 concentration of 50 ppm, the increase in the signal was 9 %. The results showed that the irradiated Cr doped ZnO nanoparticles have a higher sensitivity for detecting the presence of NH3 gas at room temperature than the undoped and unirradiated ZnO nanoparticles.