“…In order to solve these problems, we have proposed a composite electrode in which the two functions of optoelectric conversion and energy storage are individually assigned to two different materials: photocatalytic and storage materials, respectively. [4][5][6][7][8][9] The photocharging process in the composite electrodes is expected to consist of the following three elementary steps: (1) generation and separation of photoexcited electron-hole pairs within a photocatalyst, (2) transfer of photoexcited electrons (or holes) from the photocatalyst to a storage material, and (3) electrochemical energy-storage reaction caused by transfered electrons (or holes) in the storage material. Several materials have been tested for the composite electrode: TiO 2 or WO 3 was used as a photocatalyst, and a graphite-like carbon, 4) carbon fibers (CFs), 5,6) a conducting polymer 7,8) or Li x MnO 2 9) was used as a storage material.…”