Enhanced room-temperature ammonia-sensing properties of polyaniline-modified WO3 nanoplates derived via ultrasonic spray process

Low-temperature detection of ammonia (NH3) is of great significance in environmental control and human health. This paper reports an ultrasonic spray-assisted in-situ polymerization method to grow polyaniline (PANI) on the WO3 nanoplates derived by an intercalation-exfoliation process. The as-obtained WO3 @PANI (UWP-x) nanocomposites were designed with various aniline/WO3 molar ratios (x). The characterization analyses of chemical compositions and microstructure using XRD, XPS, FT-IR, SEM and TEM indicate that the WO3 @PANI samples consist of single-crystal WO3 nanoplates anchored with PANI nanoparticles. The NH3-sensing behaviors of the WO3@PANI nanocomposites were systematically evaluated. The WO3@PANI nanocomposites show higher NH3 -sensing performance than the WO3 nanoplates or PANI nanocrystals under same operating conditions. The optimized sample of UWP-2.5 is obviously sensitive to 0.5 ppm NH3, and exhibits a high response of 34 upon exposure to 100 ppm NH3 at room temperature with high stability and selectivity. Control experiments indicated that the ultrasonic spray process has played a vital role in forming PANI/WO3 nanocomposites with high NH3-sensing performance. Due to the proper anchoring and positive synergistic effect of PANI andWO(3) species, the newly-developed ultrasonic spray-assisted in-situ polymerization method provides a facile way to achieve high-performance room-temperature NH3-sensing materials.