METHOD OF PREPARING TI0.SUB.2 THICK FILM PHOTOANODES FOR PHOTOELECTROCHEMICAL CELLS

摘要

ABSTRACTSemiconductive photoanodes formed of titanium dioxide(TiO2) are known for use in photoelectrochemical cells. Theyhave been made by various techniques, including chemical vapourdeposition, thermal oxidation or anodic oxidation of thintitanium foils, hot pressing of TiO2 powder, and plasma spraying.The present invention provides a method for the fabrication ofTiO2 thick film photoanodes, which method is simple, inexpensiveand suitable for mass production of large area plates. The methodcomprises screen printing a film of conductive material on aclean alumina substrate which is then heated to fuse the conductivematerial into a conductive layer. A first layer of TiO2 particlesin an organic carrier is then screen-printed over the conductivelayer, at least 10% of the TiO2 being of anatase form. Thestructure is then heated to burn off the organic carrier andto transform at least part of the TiO2 from anatase form torutile form, this resulting in good adhesion of the TiO2 layerto the conductive layer. A second layer of TiO2 is thenscreen-printed over the first layer and heated, the secondlayer being provided in case there should be pinholes in thefirst layer which would adversely affect the anode structure whensubmersed in an electrolyte. The resulting structure is thenheated in a reducing atmosphere, e.g. anhydrous ammonia orhydrogen, to transform the TiO2 to TiO2-x where x is between 0and 1, to reduce the electrical resistivity of the films.