Photoexcited-Charge Transfer and Energy-Storage Reaction of Photorechargeable TiO_2/Carbon Fibers Composite Electrodes

摘要

A TiO_2/carbon fibers (CFs) composite electrode is a solar device that converts photon energy to electrochemical energy and stores it in situ. The photoexcited-charge transfer and energy-storage reaction were studied. The results of photo-electrochemical measurements showed that the photoexcited electrons generated in TiO_2 moved to CFs via ohmic contact. From a frequency response analysis of the electrochemical impedance, it was found that the electrical energy storage was realized by the formation of lithiated carbons at the CFs side. Since a large time constant was observed in the time variation of photo-emf, it was concluded that the low formation rate of lithiated carbons was one of the causes of small photocharged quantities.