Nanocomposites Based on Anodic Titanium Oxide and Nickel Hydroxide: the Effect of Morphology on Capacitance

A method for synthesis of nanocomposite materials with nickel hydroxide and gold has been developed via electrochemical deposition of metals onto the surface of a porous film of anodic titanium oxide crystallized in anatase, followed by nickel oxidation. Porous TiO2 films exhibit low electrical capacitance after crystallization. The capacitance increases by a factor of ~9000 after partial electroreduction of TiO2. Subsequent metal deposition and nickel electrooxidation further increase the nanocomposite capacitance by more than four times (up to ~20 mF/cm2 in the potential range from 0 to 0.5 V versus the Ag/AgCl reference electrode), using Faradaic processes for recharging. It is demonstrated how the geometric characteristics of TiO2 films (thickness, distance between pore centers) influence the capacitance characteristics of both the porous TiO2 films and the TiO2-based nanocomposite materials.