Enhancement of NO2 sensing of ZnO by irradiating with high-energy Ni ions

Abstract

Although high-energy irradiation is a feasible route to amplify sensing characteristics, only a few studies have focused on this technique. In this study, high-energy (100 keV) Ni⁺ ions were irradiated onto ZnO nanoparticles at three varying ion doses (10¹⁴, 10¹⁵, and 10¹⁶ ions/cm²) for detecting NO₂. The characterization results showed that the irradiated samples contain more oxygen vacancies than the pristine sample; irradiation at the lowest dosage produces the highest number of oxygen vacancies. At 250 °C, ZnO irradiated with the lowest dose demonstrates the largest response of 120.8–10 ppm NO₂ gas. Moreover, it exhibited long-term stability, high selectivity, repeatability, and reproducibility. The optimized sensor showed a smaller decrease in its response under humid environments compared to the pristine sensor. This enhanced performance was ascribed to the formation of large numbers of oxygen vacancies through Ni⁺ irradiation. This study emphasizes the promising role of Ni⁺ irradiation and the importance of optimizing its dosage to achieve the highest sensing output.