Fabrication of Fast Responsive and Insensitive-Humidity Sensor Based on Polyaniline-WO₃-CuCl₂ for Hydrogen Sulfide Detection

Simple and low-cost hydrogen sulfide gas sensors based on polyaniline-copper chloride and polyaniline- tungsten trioxide- copper chloride composites were developed. The sensing film was produced by drop cast of the dispersed composite on top of screen-printed carbon electrodes on a flexible polyethylene terephthalate substrate. A fast onset time of detection of 10 s and 20 s towards 0.1 ppm of hydrogen sulfide were obtained for polyaniline-tungsten trioxide-copper chloride and polyaniline-copper chloride sensors, respectively. The calibration curve displays a good working range between 0.1 and 1 ppm with a limit of detection and limit of quantification of 155 and 512 ppb, respectively. The polyaniline-CuCl ₂ sensor presented a high response to humidity change. In contrast, the incorporation of tungsten oxide into the polyaniline-CuCl ₂ composite exhibited significantly improved the response time to target gas from 15 min to 4 min and make it nearly insensitive to humidity changes up to 40 %. Gas-sensing tests show that polyaniline- tungsten trioxide-copper chloride composites exhibit a high and fast response as well as an excellent selectivity to hydrogen sulfide at ppm level in room temperature. The proposed sensors could be used for different industrial applications.