From the FeCl3 solutions of different concentrations, the polycrystalline iron oxide ultrthee particles of different sizes were obtained through hydrolysis. The results of their UV-visible spectroscopy eambit the "size quatization effects". In an electrolyte, the dependence of the photocurrent-potential relations on particle size of the dispersed iron oxide particles or the adsorbed iron oxide particles on Pt electrode and redox couple are described and discusscd.
