Zinc sulfide columns by chemical conversion of zinc oxide

We report the electrodeposition of films of free-standing hexagonal columns of ZnO and their chemical conversions to ZnS and subsequent conversion to Bi2O3. The columnar shape of the original ZnO with an average diameter of 300 nm and length of 1-2 mum is kept in these processes. Reactive treatment of the grown films in sulfur vapor or H2S gas results in complete or partial conversion to ZnS and some affection of the underlying SnO2 substrate. The chemically less stable ZnO cores of partially converted columns can be dissolved so that ZnS tubes with wall thickness up to 50 nm remain. Reactive treatment of the ZnS tubes in slightly acidic solutions of selected heavy metal salts results in tubes of the respective metal sulfide. The described procedures open a way to convert a microstructured material into a choice of chemically more stable materials with the same morphology, thus, leading to a diversification of possible applications. (C) 2002 Elsevier Science B.V. All rights reserved.