Polypyrrole-Ru(2,2'-bipyridine)3(2+)/MoSx structured composite film as a photocathode for the hydrogen evolution reaction.

The development of photoelectrochemical devices for solar light-driven water splitting and H2 production requires new strategies for the fabrication of materials that combine the necessary photoredox and catalytic properties, to allow the hydrogen evolution reaction (HER) to take place at a low overvoltage under visible light irradiation. We report the first example of a structured composite, synthesized by electrodeposition of MoSx cocatalyst into a photosensitive Ru complex film deposited onto carbon electrodes by electropolymerization of a pyrrole-functionalized Ru(II)(2,2'-bipyridine)3(2+). Composite films show efficient photocatalytic activity for HER. Our study highlights the great simplicity of this versatile electrochemical procedure to synthesize photocathodes.