Synergistic conductivity increase in polypyrrole/molybdenum disulfide composite

Polypyrrole/molybdenum disulfide (PPy/MoS2) composites were synthesized by in situ chemical polymerization of pyrrole in the presence of MoS2 flakes. The conductivity of the composite with a moderate content of PPy (15-30 wt%) reached 13 S cm(-1) , which is markedly higher than the conductivity of both the pristine PPy and MoS2 ,1 and 10(-6) S cm(-1) , respectively. The improved conductivity was explained by the formation of ordered thin PPy films with high conductivity at the MoS2 surface. At higher pyrrole content, globular PPy was formed in the bulk of the composite resulting in an increase of a disordered polymer fraction, and the conductivity decreased. The composite conductivity is thus controlled not only by content of PPy but also by the proportions between ordered and disordered PPy phases. The structural and morphological characterization of composite materials is based on Fourier-transform infrared and Raman spectroscopies, wide-angle X-ray diffraction, and scanning and transmission electron microscopies. The charge-carrier transport in the composites fits the Mott variable-range hopping mechanism. (C) 2018 Elsevier Ltd. All rights reserved.