Highly sensitive and rapid chemiresistive sensor towards trace nitro-explosive vapors based on oxygen vacancy-rich and defective crystallized In-doped ZnO

摘要

In order to sensitively detect trace nitro-explosive vapors, the sensing properties of ZnO nanoparticles (NPs) are boosted by tailoring the doping level of indium (In). With the introduction of In, the shape of the ZnO NPs changes from sphere with grain size of 55.2 ± 9.6 nm to irregular NPs with a reduced size. The sensing performances of sensors towards room-temperature saturated nitro-explosive vapors generally increase firstly and then decrease, peaking at an atomic ratio of 1.29% (corresponding to 5% In in the precursor). The 5% In-doped ZnO nanoparticle-based sensor exhibited remarkably enhanced responses towards trace nitro-explosive vapors, including TNT of 9 ppb, DNT of 411 ppb, PNT of 647 ppb, PA of 0.97 ppb and RDX of 4.9 ppt at room temperature. For instance, compared with ZnO, the responses to nitro-explosive vapors were increased from 22.2,8.5,2.9,4.9 and 9.8% to 54.7,52.9,57.2,58.3 and 47.4%, respectively. Furthermore, much shorter response time (<6.3 s vs. 20-40 s) and recovery time (<14s vs. 20-40 s) were achieved, which is of vital importance for on-site explosive detection. Combining the surface oxygen defects investigation, it is found that the remarkably increased oxygen vacancies are responsible for the sensing performance improvement.