Conducting polymer-bridged three-dimensional heterojunctions of reduced graphene oxide/γ-Fe2O3 hybrids for high-performance NO2 gas sensing

Abstract

Three-dimensional (3D) reduced graphene oxide (RGO) networks show potentials for highly sensitive gas sensors. However, many insulating materials are usually used during RGO assembly process, which inevitably hinder the electron transfer efficiency, and affect the gas sensing performance. In this work, 3D structures based on nanospheres of conducting polymer layer-bridged γ-Fe2O3/RGO hybrids have been designed and demonstrated for NO2 sensing. Polyaniline (PANI), as a conducting polymer, can not only serve as self-assembly reagents to construct 3D hybrid structures, but also play an important role in participating electron transfer through forming p-n heterojunctions between interfaces of γ-Fe2O3 and RGO. The manufactured γ-Fe2O3@PANI@RGO sensors show a response as high as 911% when exposure to 50 ppm NO2, being over 124 times those of bare two-dimensional graphene sensors. In addition, excellent selectivity, stability, and low detectable concentration (100 ppb) to NO2 can be achieved for sensors based on this unique structure. It is​ suggested that the high performance can be ascribed to the formed 3D structures based on as-designed p-n heterojunctions and conjugation effect of PANI. The design strategy as well as constructed 3D RGO can provide a general route to fabricate high-performance gas sensors.

Keywords

• Three-dimensional graphene hybrids
• Polyaniline
• Core–shell structure
• Heterojunctions
• Gas sensor