Protection of CdSe Oxygen Photoanodes by Poly(bithiophene)‐Polypyrrole Composites and Copolymers

Abstract

Protection of CdSe photoanodes for oxygen evolution in water by polypyrrole (PPy) and poly(bithiophene) (PBT) coating is shown to be inefficient. Although PBT layers are very dense and adhesive, the oxygen production is low due to high resistivity and bad catalytic behavior. Better results are achieved with PPy, but some degradation appears with time as the polymer undergoes irreversible changes in the presence of water containing oxygen. [PBT-PPy] composites and P(BT, Py) copolymers were grown by successive or simultaneous polymerization of PBT and PPy. Both of these coatings gave improved prolection. A stabilization of 50% was obtained with P(BT, Py) copolymer. Enhanced stabilization of the semiconductor and the protecting polymer was achieved by including a catalyst (Pd or Ru02) into the coating layer. Photocurrent losses due to the absorption by the catalyst was observed with palladium but not with Ru02. © 1988, The Electrochemical Society, Inc. All rights reserved.