A formaldehyde sensor: Significant role of p-n heterojunction in gas-sensitive core-shell nanofibers

Abstract The metal oxide semiconductor (MOS) core-shell heterostructure nanofibers (NFs) have been successfully fabricated via a facile and environmentally friendly coaxial electrospinning approach. In this work, p-type semiconductor Co 3 O 4 and n-type semiconductor ZnO are chosen for the synthesis of the core-shell heterostructured NFs. The Co 3 O 4 -ZnO core-shell NFs show a normal p-type response to formaldehyde in spite of the n-type ZnO shell. This conversion of sensing behavior may attribute to the formation of p - n heterojunction. Additionally, Co 3 O 4 -ZnO core-shell NFs exhibits enhanced sensing performance including a high response to the target gas and rapid response/recover processes. A possible mechanism of the improved sensing abilities is also illustrated, which can provide theoretical guidance for the further development of advanced gas-sensitive NFs with p - n heterojunction.