Room temperature ammonia gas sensor based on polyaniline/copper ferrite binary nanocomposites

In this work, a polyaniline/copper ferrite (PANI/CuFe2O4) heterostructure was synthesized by in situ polymerization for the first time, and a high-performance NH3 sensor was developed by coating the heterostructure onto a substrate with staggered electrodes. The composition, chemical state and morphology of the PANI/CuFe2O4 composite was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The TEM and SEM results showed that the CuFe2O4 had a nanometer microsphere structure and PANI nanocapsules that were rod-like. The sensitivity of the PANI/CuFe2O4 sensor to different concentrations of NH3 gas was investigated at room temperature. The experimental results showed that the PANI/CuFe2O4 film shows excellent performance in terms of high response and selectivity: the response at 5 ppm ammonia was found to be as high as 27.37 %, which was clearly superior to that found for pristine PANI and CuFe2O4 films. The PANI/CuFe2O4 nanocomposite showed excellent sensitivity toward NH3 sensing, which can be attributed to the interaction between p-n heterojunctions in the binary nanocomposite. In addition, an ammonia alarm circuit based on the fabricated sensor was developed to realize practical applications for the detection of ammonia concentrations beyond the current limits.