Hydrothermal synthesis of hierarchically porous Rh-doped ZnO and its high gas sensing performance to acetone

The hierarchically porous Rh-doped ZnO and pure ZnO samples have been successfully synthesized through a simple hydrothermal reaction process at 180 degrees C. The morphology and composition were carefully characterized by X-ray diffraction, field emission scanning electronic microscopy, transmission electron microscopy and BET. Gas-sensing testing results demonstrated that ZnO doped with 1 mol% Rh significantly improve gas sensitivity from pure ZnO. The high sensitivity of the sensor based on 1 mol% Rh doping ZnO was of 142-100 ppm acetone, the response increased linearly with the concentration of acetone in the range of 50-1500 ppm. All the response and recovery times of the sensors were less than 20 s at a low working temperature of 340 degrees C. The improved response of Rh-doped ZnO sensor was related to the electronic interaction of Rh2O3 and ZnO due to heterojunction formation. The good sensing performances of the Rh-doped ZnO sensor indicated that hierarchically porous Rh-doped ZnO could be a promising candidate for highly sensitive gas sensors.