The Ion-Storage Capacity and Surface Characterization of Ce/Cu Thin Films

摘要

Ce/Cu mixed oxide thin films with molar ratio 1 were prepared by sol-gel method and dip-coated on SnO2/F covered glass.The cyclic voltammetry and chronocoulometry were carried out to determine their suitability for application as a counter-electrode in electrochromic devices.The charge capacity is up to 20 mC cm~(-2),however,the reversibility of the redox process decreases with the number of cycles.Surface composition and chemical bonding of elements on the surface of the cycled and non-cycled part of the Ce/Cu mixed oxide thin film were investigated by X-Ray photoemission spectroscopy(XPS)and surface morphology was analyzed by atomic force microscopy(AFM).The Cu atoms on the non-cycled surface are bonded as Cu(2+),whereas after cycling the Cu atoms are reduced to Cu(l+).The Ce atoms in both areas are in the Ce(4+)state.The Ce/Cu ratio measured by XPS on the surface of the non-cycled area is higher than on the surface of the cycled one.In the cycled area the Li is present,bonded in thin film as Li2CO3.