Surface modification of tungsten disulfide with polypyrrole for enhancement of the conductivity and its impact on hydrogen evolution reaction

Abstract

A conducting polymer, polypyrrole, was deposited on tungsten disulfide flakes in situ during the oxidation of pyrrole. The conductivity of composites exceeded the conductivities of the parent components. This synergistic effect is explained by the deposition of more conducting ordered polypyrrole at first, and less conducting globular polypyrrole later after the whole available tungsten disulfide surface was coated. Such scenario was confirmed by electron microscopies. Raman and X-ray photoelectron spectroscopies proved the completeness of the coating. Despite the increase in the conductivity, the electrocatalysis of hydrogen evolution reaction on tungsten disulfide was reduced after polypyrrole deposition, confirming also effective coating of the substrate. A simple mixture of both components, however, improved the electrocatalytic effect compared with the composite or any of its components.