Design of supersensitive and selective ZnO-nanofiber-based sensors for H2 gas sensing by electron-beam irradiation

In the present study, ZnO nanofibers (NFs) were synthesized by the simple electrospinning technique for gas sensing studies. ZnO NFs were irradiated with a high-energy (1 MeV) electron beam (e-beam) at different doses (50, 100, and 150 kGy) to study the effect of the e-beam dose on the sensing performance of the synthesized ZnO NFs. H-2 sensing studies showed that the sensing properties of the unirradiated and 50 kGy-irradiated sensors were similar, which indicates that this e-beam dose was insufficient. However, the sensing characteristics improved with an increase in the irradiation dose to 100 and 150 kGy. The response of the optimal sensor (150-kGy-irradiated) to 10 ppm H-2 was much higher than that to other (interfering) gases (e.g., C2H5OH, C6H6, C7H8, and CO). The observed high gas response of the 150 kGy-irradiated sensor was attributed to its high surface area resulting from the one-dimensional nature of the ZnO NFs, the grain size of ZnO, and the formation of surface defects by e-beam irradiation. The high selectivity of the ZnO NFs toward H-2 gas was related mainly to the metallization of ZnO and the concentration gradient of carfbon across the NF surfaces. Overall, the findings demonstrate the effectiveness of high-energy irradiation in enhancing the sensing performance of ZnO NFs. We believe that this approach can be extended to other metal oxides for the enhancement of sensing performance.