Controllable synthesis of crescent-shaped porous NiO nanoplates for conductometric ethanol gas sensors

NiO has been widely used as building blocks for gas sensing because of its excellent physicochemical properties. However, the high working temperature of most NiO-based sensors (< 200 degrees C) hinders their further applications. In this work, a novel nanostructure, crescent-shaped porous NiO nanoplates, has been synthesized via hydrothermal approach combining with calcination treatment, which shows low working temperature for ethanol gas sensing. The volume ratio of ethanol to distilled water, the adding amount of PVP, and annealing temperature have been investigated in detail for precisely controlling the morphology of NiO nanostructure. Subsequently, the crescent-shaped porous NiO nanoplates are employed to fabricate conductometric ethanol gas sensors. Under optimal experimental conditions, the NiO nanoplates based gas sensor demonstrates fast response and recovery speed (5 and 20 s, respectively) to 100 ppm ethanol at a low working temperature of 130 degrees C with excellent long-term stability and selectivity. Furthermore, the limit of detection is experimentally calculated to be as low as 200 ppb. The results show that the crescent-shaped porous NiO nanoplates has great potential in ethanol sensing applications and the feasibility of morphology control for high performance gas sensing.