Preparation And Their Gas-sensing & Electrochemical Properties Of PANI-metal Oxide Hybrid Material

In this paper, the polyaniline doped by hydrochloric acid was synthesis by the classical chemical oxidation polymerization, coral-like SnO₂ mesoporous material was prepared by hydrothermal method using SnCl4·5H₂O as raw material and glucose as the template, Three kinds of different doping content of polyaniline-coral-like SnO₂ hybrid material was prepared by in-situ polymerization using coral-like SnO₂ mesoporous material as the template. Coral-like SnO₂, polyaniline and polyaniline-coral-like SnO₂ hybrid material were characterized by FT-IR, XRD, FE-SEM, TEM, BET, etc, and the gas-sensing properties to NH3, trimethylamine, SO₂ of polyaniline-coral-like SnO₂ hybrid material at room temperature and electrochemical properties as supercapacitor also have been investigated. The main results are as follows:1. The gas-sensing properties of polyaniline-coral-like SnO₂ hybrid material: The as-prepared SnO₂ has tetragonal rutile structure. The average crystalline size of SnO₂ was estimated by the Willamson-Hall plot to be 10.6 nm. The surface morphology of SnO₂ material was similar to a kind of marine organism called coral, and the coral-like SnO₂ had cross-linked structure in deep zones. The coral-like SnO₂ was mesoporous structure. The pore size was 5.6 nm, and the specific surface area reached up to 63.3 m2/g. The higher specific surface area and mesoporous structure would be advantageous for gas adsorption-desorption and enhance the gas sensing properties. Therefore, the polyaniline-coral-like SnO₂ hybrid material which used coral-like SnO₂ mesoporous material as a template have higher specific surface and more transportable passage of gas molecules. The results of gas sensing tests exhibited that the sensibility?to NH3, trimethylamine and SO₂? of polyaniline-SnO₂ hybrid material which the mass ratio of polyaniline and SnO₂ was 70:30 was better than the other. Therefore, we choose the polyaniline-SnO₂ with a mass ratio of 70:30 and the polyaniline to take part in a gas-sensing comparison test, the results showed that the sensitivity of polyaniline-coral-like SnO₂ gas sensor were a time more than the polyaniline gas sensor to different concentrations of ammonia and trimethylamine at room temperature. The response time of polyaniline gas sensor to a low concentration of 200 ppm ammonia is 200 s, and it is difficult to recovery. Under the same condition the response and recovery time of polyaniline-coral-like SnO₂ gas sensor were 60 s and 500 s. The response time of polyaniline gas sensor to a high concentration of 600 ppm ammonia is 150 s, and the recovery time is more than 1000 s. Under the same condition the response and recovery time of polyaniline-coral-like SnO₂ gas sensor were 40 s and 540 s. Polyaniline-coral-like SnO₂ gas sensor exhibited more excellent response and recovery performance than polyaniline gas sensor to different concentrations of trimethylamine, the response time of polyaniline-coral-like SnO₂ gas sensor to a low concentration of 200 ppm trimethylamine is 480 s, and the recovery time is 530 s. Under the same condition the response and recovery time of polyaniline gas sensor were 490 s and more than 800 s. The response time of polyaniline and polyaniline-coral-like SnO₂ gas sensor to a high concentration of 600 ppm trimethylamine has similar value, but the recovery time of polyaniline-coral-like SnO₂ gas sensor was so much faster than polyaniline gas sensor. The sensitivity of polyaniline-coral-like SnO₂ gas sensor has obviously improved than the polyaniline gas sensor to different concentrations of SO₂ at room temperature. The sensitivity of polyaniline-coral-like SnO₂ gas sensor to 200 ppm SO₂ was 1.6 and 600 ppm was 5.7, under the same condition, the sensitivity of polyaniline gas sensor were 1.2 and 2.2. In addition, the time stability of sensitivity of the polyaniline-coral-like SnO₂ hybrid material was better than that of polyaniline.2. The electrochemical properties and capacitance characteristics of polyaniline-coral-like SnO₂ hybrid material: The polyaniline-coral-like SnO₂ hybrid material which used coral-like SnO₂ mesoporous material as a template has higher specific surface and more transportable passage of molecules so that the hybrid material in the electrolyte have large contact area and more electrochemical reactive sites which enabled the energy storage performance of hybrid material with respect to the polyaniline significantly improved. The electrochemical performance and capacitance characteristics were tested by cyclic voltammetry, chronopotentiometry and AC impedance. The result shows that, when the mass ratio of coral-like SnO₂ and aniline was 15:85 and 30:70, the specific capacitance of polyaniline-coral-like SnO₂ hybrid material was 385 F/g and 440 F/g at the current density of 0.15 A/g, more than that of polyaniline which was 304 F/g. The resistance between the electrode surface of hybrid material and the electrolyte was 2.5 ? and 2.3 ?, less than that of polyaniline which was 3.7 ?, while the cycling stability of the hybrid material has also been significantly enhanced.