High performance mixed-potential-type Zirconia-based NO₂ sensor with self-organizing surface structures fabricated by low energy ion beam etching

The mixed-potential-type NO₂ sensor based on a yttria-stabilized zirconia (YSZ) electrolyte with NiO sensing electrode and a three-phase boundary (TPB) was fabricated. The ion beam etching (IBE) technology with low energy was employed to etch the YSZ substrate for the first time. The characterization result indicates that the YSZ substrate prepared by argon ion (Ar⁺) beam with different incident angles (10° and 40°) obtains hollow and spike patterns on the surface, respectively. The sensing performance was improved by the self-organized nanostructures of TPB, which enhances the contact area obviously. The sensor using a YSZ substrate processed by 10° incident angle with 800 eV/60 mA energy demonstrates the largest response compared with other parameters to NO₂ at 850 °C. Sensitivity of the sensors is achieved as 40.7 mV/decade, about 1.9 times as the initial YSZ substrate. In addition, the sensor also has good response-recovery transients, repeatability and selectivity.