In this work, sol-gel (SG) oxide films were formed by dip-coating Pt substrates from Ni, Co, and mixed Ni-Co sols. After withdrawing the substrate at a constant rate, the films were dried between 100 and 400ЊC for various periods of time (15 min to 1 h). Based primarily on the cyclic voltammetric behavior of the SG-formed Ni-Co films after drying at high temperatures, it is suggested that both the Ni and Co sites undergo redox reactions in 1 M NaOH solutions. This also explains the high charge

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... fficiency and charge density of SG-derived, Co-containing Ni oxide films. Careful optimization of the experimental variables in the SG film preparation route indicated that the use of 50:50 Ni-Co sols, a withdrawal rate of 6 cm/min, and drying at 250ЊC for 1 h yields films which display the highest charge density, the most rapid redox kinetics, and good stability to prolonged potential cycling. In addition, the charge capacity of the optimized 50:50 Ni-Co SG oxide films can be increased further by the deposition of multilayers. The redox kinetics of the optimized coatings in 1 M NaOH solution were superior to those for Ni-Co oxide films of comparable charges, but formed in other ways. Diminished reaction rates resulted when higher film drying temperatures were used (denser films) and when thicker, multilayered films were formed.