1D/2D Heterostructured WS₂@PANI Composite for Highly Sensitive, Flexible, and Room Temperature Ammonia Gas Sensor

Flexible and room-temperature (RT) ammonia gas sensors are needed for exhaled breath detection and recognition. Two-dimensional transition metal disulfides are potential materials for RT gas sensing because of their low band gap and a large number of edge-exposed sites that can provide strong binding to gas molecules. In this work, a 1D/2D heterostructured composite material of 2D tungsten disulfide (WS₂) modified with 1D polyaniline (PANI) was proposed. The fibrous PANI adsorbed on the edges and inserted in the interlayers of the laminated WS₂ provide more diffusion channels for the ammonia gas and act as sensing sites. The WS₂@PANI-based sensor shows high selectivity for ammonia with satisfying reproducibility and long-term stability. A response of 216.3% and a short response/recovery time of 25 s/39 s were achieved for 100 ppm ammonia gas. The sensing mechanism was investigated in detail via complex impedance spectra and in situ FT-IR, which was attributed to the synergistic effect of WS₂ and PANI. The excellent sensing performance coupled with its resistance to thermal and humidity interference endows the WS₂@PANI-based sensor with potential for human exhaled detection and wearable electronics.