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

Development of chemo-resistive room-temperature ammonia (NH 3 ) sensor with high performance remains a great challenge to this day. In this paper, we demonstrate a room-temperature NH 3 sensor based on organic-inorganic cobalt ferrite (CoFe 2 O 4 )/polyaniline (PANI) composite. The CoFe 2 O 4 porous nanosheets were firstly prepared by using a direct precipitation method, and then the PANI were anchored onto the surfaces of the CoFe 2 O 4 porous nanosheets through an in-situ polymerization process to form the CoFe 2 O 4 /PANI composite. The crystal structure, morphology, and surface chemistry of the CoFe 2 O 4 /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 CoFe 2 O 4 and PANI, the CoFe 2 O 4 /PANI gas sensor exhibited excellent NH 3 -sensing performance with high response (13 to 100 ppm NH 3 ), good selectivity, wide detection range (10–500 ppm), and rapid response/recovery rate (18/31 s to 100 ppm NH 3 ) at room temperature. Additionally, the CoFe 2 O 4 /PANI gas sensor owned outstanding repeatability and long-term stability. This study offered a promising candidate of CoFe 2 O 4 /PANI composite for constructing room-temperature NH 3 sensor.