Side-by-side design of bi-component heterojunction nanofibers for high-performance gas sensors: Improvement in synergistic effect

Heterojunctions are often introduced into gas sensor electrodes due to they can lower the working temperature and increase response rate during gas-sensing detection. However, many reported core–shell structured heterojunctions show a bad synergistic enhancement effect from both components. Here, a type of side-by-side bi-component heterojunction nanofibers of NiO/In₂O₃ (INO SBHNFs) was designed by the self-made V-channel electrospinning technique. Results showed that these SBHNFs are comprised of two component NFs that attach together side-by-side with a well-defined interface. And the sensors based on INO-10 SBHNFs show the highest response of 210 to 100 ppm ethanol at 260 °C, which is an order of magnitude higher than all those of the ones based on the In₂O₃ and INO-10-C NFs. Moreover, the INO-10 SBHNF sensors also show a high response recovery rate (4 s/36 s) and a low limit of detection (<200 ppb). Further analysis indicates that this side-by-side design can totally utilize the heterojunctions’ motivation and the solid solution's enhancement on the formation of depletion layer (including the transfer of electrons), and the synergistic enhancement effect from both components and their surface. Besides, the sensors based on INO SBHNFs also show a good selectivity, as well as a high long-term stability.