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. H2 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 H2 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 H2 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.