Polymer-Modified Electrodes, Catalysis and Water-Splitting Reactions

Highlights of results on surface modified CdS semiconductors in the presence and absence of an externally applied anodic bias are presented. At zero applied bias, the surface modification involved coating the faces of CdS with electrically conductive polypyrrole and catalytic dispersions of transition metals (Pt, Rh, RuO₂) immobilized in polystyrene films. The combination of polypyrrole and catalytic polystyrene films prevented photo-induced dissolution of CdS and catalyzed H₂ and O₂ evolution. The amount and composition of metal dispersed in the polystyrene coating and the hydrophobic nature of the films were important in achieving good catalytic activity and stability of the CdS semiconductor. Sorption processes, the electronic contact between the polymer and the semiconductor and the particular transition metal catalyst selected also influenced the net yield of H₂.