Abstract
Electrochemical growth of ZnO/eosinY hybrid thin film was investigated. Two deposition potentials of -0.8 and -1.0 V vs. SCE were chosen to clarify the relationship between the redox state of eosinY and the structure of the products, because eosinY has its reduction potential at around -0.9 V. The hybrid thin film deposited at -0.8 V has a dense structure, while that at -1.0 V has a nanoporous structure. Almost steady current was observed during the potentiostatic electrodeposition. Deposition rates in film thickness, molar amount of ZnO and of eosinY were determined. Linear growth and constant composition were found regardless of the deposition potentials. The adsorption rate of eosinY at -1.0 V was about 10 times higher than that at -0.8 V. Because eosinY molecules can occupy as much as 38% of the total volume of the hybrid film deposited at -1.0 V, the film comes to possess an open porous structure after removal of the dyes by dipping the film in dilute KOH: On the other hand, eosinY molecules appear to be surrounded by ZnO due to the much lower loading efficiency at -0.8 V, so that the hybrid film is grown in a dense structure from which dyes cannot be fully removed by the KOH treatment.
