Research On Humidity Sensitive Performance Of Composites Of Vanadium(Vanadium-titanium) Acid And Polyaniline

With the reaction materials being vanadium pentoxide and butyl titanate, the reaction reagent being H2O2 of 30 percent, vanadium(vanadium-titanium) acid xerogel thin films are produced respectively using sol-gel method. The influence from Ti content and times of coating on the humidity sensitive performance of the composite synthetic acid is investigated. The humidity sensing characteristic, the response-recovery property and long-term stability of the element are researched. The results show that the element has a good sensitivity, but a bad stability, that improvement and enhancement of it are needed.Sulfuric acid / polyaniline thin film humidity sensitive element is made by the method of electrochemical polymerization, and the stability of the element is better. However, in the whole humidity range, the resistance value only changes less than an order of magnitude with a larger humidity hysteresis, so that its sensitivity should be improved. Potentiostatic method and cyclic voltammetry are adopted to make the vanadium(vanadium-titanium) acid / polyaniline films, and the research on the humidity sensitive properties show that the humidity sensitive performance of vanadium(vanadium titanium acid) / polyaniline film is superior to that of sulfuric acid / polyaniline thin film element evidently. Also, FTIR、UV-vis and SEM representations are carried on for the made vanadium( vanadium titanium acid) / polyaniline films, the influences from different electrochemical synthetic methods on the humidity sensitive performance of the element are inspected, and the best way to synthesize the humidity sensitive element is confirmed. The research on the humidity sensitive characteristic indicates that the humidity sensitive performance of vanadium titanium acid / polyaniline humidity sensitive element is the best. The resistance of the element has changed three orders of magnitude with the humidity hysteresis being only 4 percent and a better linearity, also, the stability has been improved greatly in contrast with vanadium acid / polyaniline films. Finally, the humidity sensitive mechanism of double-layered vanadium titanium acid / polyaniline films is investigated using polar inversion method, charge-discharge method and complex impedance method. The results show that the humidity sensitive performance of double-layered vanadium titanium acid is superior to that of other elements, and the sensitivity, linearity, humidity hysteresis and stability all have been improved. In wet material ion is involved, conductive and conductive ion with the increase of humidity activation energy is reduced, in the process of humidity increases, participate in conductive ions and electrons are more, and the resistance drop, increase capacity.