Enhancement of photocatalyic activity of dye sensitised anatase layers by application of a plasma-polymerized allylamine encapsulation

A polyallylamine coating was applied as a protective encapsulation to iridium dye sensitised TiO2 catalyst layers by a plasma-enhanced chemical vapour deposition process. A significant enhancement of the incident-photon-to-current efficiencies of the polymer-confined dye/catalyst assembly was observed, with a strong dependence on the nominal thickness of the polymer-coating. An optimum thickness of the polyallylamine coating between 15 and 50 nm was obtained with regard to photoefficiency of the polymer-coated dye/TiO2 catalyst in a neutral electrolyte. Results are discussed in terms of porosity and electrolyte permeability of the plasma polymer layer.