In this study, we report on the synthesis of the NiO/ZnO heterostructured nanowires by a facile two-step liquid phase route and their gas sensing characteristics employing Au interdigitated electrodes integrated on a miniature ceramic heater. Microstructural characterizations indicate that flocculent NiO particles are uniformly assembled on the outer surfaces of the single-crystalline ZnO nanowires, with diameters around 50 nm and lengths ranging from 500 nm to several μm. The gas sensing investigation indicates that the sensors based on NiO/ZnO heterostructured nanowires exhibit high sensitivity towards ethanol, good reversibility, reproducibility, stability, robustness towards humidity, and fast response/recovery rates at the determined optimum operating temperature of 300 °C. Interestingly, the sensor shows higher ethanol response but longer recovery time in N2 compared with those in air. An ethanol sensing mechanism is proposed to explain the experimental results.
Keywords: Heterostructure; NiO; ZnO; Nanowires; Ethanol sensing; Gas sensing