Silver Anchored Polyaniline@Molybdenum Disulfide Nanocomposite (Ag/Pani@MoS 2 ) for Highly Efficient Ammonia and Methanol Sensing under Ambient Conditions: A Mechanistic Approach.

We report the synthesis of silver anchored and para toluene sulfonic acid ( p TSA) doped polyaniline/molybdenum disulfide nanocomposite ( p TSA/Ag-Pani@MoS 2 ) for highly reproducible room temperature detection of ammonia and methanol. Pani@MoS 2 was synthesized by in situ polymerization of aniline in the presence of MoS 2 nanosheets. The chemical reduction of AgNO 3 in the presence of Pani@MoS 2 led to the anchoring of Ag to Pani@MoS 2 and finally doping with p TSA produced highly conductive p TSA/Ag-Pani@MoS 2 . Morphological analysis showed Pani-coated MoS 2 along with the observation of Ag spheres and tubes well anchored to the surface. Structural characterization by X-ray diffraction and X-ray photon spectroscopy showed peaks corresponding to Pani, MoS 2, and Ag. The DC electrical conductivity of annealed Pani was 11.2 and it increased to 14.4 in Pani@MoS 2 and finally to 16.1 S/cm with the loading of Ag. The high conductivity of ternary p TSA/Ag-Pani@MoS 2 is due to Pani and MoS 2 π-π* interactions, conductive Ag, as well as the anionic dopant. The p TSA/Ag-Pani@MoS 2 also showed better cyclic and isothermal electrical conductivity retention than Pani and Pani@MoS 2, owing to the higher conductivity and stability of its constituents. The ammonia and methanol sensing response of p TSA/Ag-Pani@MoS 2 showed better sensitivity and reproducibility than Pani@MoS 2 owing to the higher conductivity and surface area of the former. Finally, a sensing mechanism involving chemisorption/desorption and electrical compensation is proposed.