Figure 6.

a) Structure illustration of one three‐electrode photocatalytic charging system. The photo‐capacitor consists of a dye‐sensitized TiO₂ photoelectrode, a Pt‐plate counter electrode and a Pt‐coated glass charge storage electrode covered with activated carbon, spacer, separator, and electrolytes. Reproduced with permission.39 Copyright 2005, The Royal Society of Chemistry. b) Principle illustration of a three‐electrode photocatalytic charging system based on double‐sided TiO₂ nanotube arrays. The top side of the Ti foil is used as photoelectrode in the DSSC part and the bottom part acts as anode part in a typical lithium ion battery for energy storage. Reproduced with permission.44 Copyright 2012, American Chemical Society.