Room-temperature NH3 sensor based on CoFe2O4/PANI composite with porous structure

Abstract

Development of chemo-resistive room-temperature ammonia (NH3) sensor with high performance remains a great challenge to this day. In this paper, we demonstrate a room-temperature NH3 sensor based on organic-inorganic cobalt ferrite (CoFe2O4)/polyaniline (PANI) composite. The CoFe2O4 porous nanosheets were firstly prepared by using a direct precipitation method, and then the PANI were anchored onto the surfaces of the CoFe2O4 porous nanosheets through an in-situ polymerization process to form the CoFe2O4/PANI composite. The crystal structure, morphology, and surface chemistry of the CoFe2O4/PANI composite were characterized by combined techniques of X-ray diffraction, electron microscopy, and spectroscopy. Due to the porous feature of the composite and the formation of p-p heterojunctions between the CoFe2O4 and PANI, the CoFe2O4/PANI gas sensor exhibited excellent NH3-sensing performance with high response (13 to 100 ppm NH3), good selectivity, wide detection range (10–500 ppm), and rapid response/recovery rate (18/31 s to 100 ppm NH3) at room temperature. Additionally, the CoFe2O4/PANI gas sensor owned outstanding repeatability and long-term stability. This study offered a promising candidate of CoFe2O4/PANI composite for constructing room-temperature NH3 sensor.