Methanol sensors based on the conductive polymer composites from polypyrrole and poly (vinyl alcohol)

Abstract

Methanol sensors based on polypyrrole-poly(vinyl alcohol) (PPy-PVA) composite films were prepared electrochemically with various charges, ranging from 0.05 to 0.20 C. The sensing abilities, including sensitivity, response time and recovery time, to various methanol-vapor concentrations, ranging from 15 to 218 mg l −1, were investigated. The methanol-sensing ability was dependent on the electropolymerization charge and was better if a lower charge was applied. A sensitivity of 9.70 mΩ mg l −1, about nine times the sensitivity of the pristine PPy sensor, was measured by the PPy-PVA sensor prepared at 50 mC.The PPy-VA composite sensors responded as quickly as 33 s in a methanol concentration of 218 mg l −1. PVA loading in the electrolytic solution showed an effect on the sensitivity of the sensor and exhibited an order of 7.5 g l −1 >5.0 g l −1 > 10.0 g l −1> 1.0g l −1> pure PPy. However, we also found that the stability of the PPy-PVA composite sensor under exposure to methanol vapor was poorer than that of the pure PPy sensor.