Ternary WS2/GaN/PANI Nanocomposites for Thermodynamically and Kinetically Enhanced Ammonia Gas Sensing at Room Temperature

Abstract The detection of ammonia (NH3) is of crucial importance for environmental protection, agricultural safety, and industrial process control. In this work, a ternary WS2/GaN/PANI (WGP) nanocomposite was designed from both thermodynamics and kinetics perspectives. The WGP nanocomposite was fabricated via a sequential thermal treatment of WS2 and GaN, followed by in situ polymerization of aniline. The resulting sensor achieved a high response of 187.66% to 50 ppm NH3 at room temperature, which is 4.2× that of pristine WS2. The enhanced response dynamics was demonstrated by the short response/recovery times of 16 s/24 s. Comprehensive characterizations, including electrochemical impedance spectroscopy (EIS), electron paramagnetic resonance (EPR), and quasi-in-situ X-ray photoelectron spectroscopy (XPS), revealed that the superior performance originates from the synergistic effects among the three components, the formation of heterojunctions, and enhanced charge transfer. The provision of multiple sites and the increased concentration of oxygen vacancies both contribute to the enhanced ammonia gas-sensing performance of the WGP nanocomposite. With its reliable and stable response, the WS2/GaN/PANI sensor offers a promising solution for real-time ammonia monitoring in chicken coop environments.