ZnO coral-like nanoplates decorated with Pd nanoparticles for enhanced VOC gas sensing

Abstract

Abstract A high working temperature of the ZnO nanomaterial-based gas sensor could shorten the lifetime of the sensor and increase its power consumption. Enhancing the VOC sensing performance of ZnO nanomaterials-based gas sensors in terms of gas response and temperature is vital for their practical application. Decoration of noble metals onto nanostructures is an effective approach to improve their sensing characteristics. Herein, hydrothermally synthesized ZnO coral-like nanoplates decorated with Pd nanoparticles, are introduced to achieve the improved VOC sensing performance. The morphology, crystal structure, composition, atomic structure, and gas sensing properties of the synthesized pristine and Pd-ZnO coral-like nanoplates were investigated. The results showed a remarkable reduction of optimal working temperature from 450 °C for the pristine ZnO sensor to 350 °C for the Pd-ZnO sensor. The sensor response to acetone at the optimal operating temperature of 350 °C was improved three times by surface decoration with Pd nanoparticles. Response and recovery times of the Pd-ZnO sensor were about three times faster than that of the pristine ZnO sensor. The Pd-ZnO sensor had a theoretical detection limit of 17 ppt and a sensitivity of 3.5 to 2.5 ppm acetone at 350 °C. The sensor transient stability after several on/off switching cycles from air to gas revealed the effective reusability of the fabricated devices. A plausible mechanism for the VOC sensing of the porous Pd-ZnO coral-like nanoplate-based sensor was also discussed.