Electrochemistry of Titanate(IV) layered oxides

The electrochemical properties of the Cs(x)Ti((2-x/4))square O-x/4(4) (C-T) layered oxide, whose electrode was prepared using an electrophoretic deposition (EPD) technique, were measured in aqueous solutions. The EPD technique was used for fixation of the C-T oxide powder onto a Pt substrate using its methanol, ethanol, acetone, and amine/H2O suspensions. Highly (0n0)-oriented films of the layered oxide were obtained in the alcohol and amine/H2O solutions due to exfoliation and migration. A large anodic photocurrent was observed at the deposited C-T oxide in the solutions with pH lower than about 10-11 (PZC), but not in alkaline solution. H3O+ and/or H2O intercalation occurred in solutions with pH lower than the PZC. The anodic photocurrent is due to the photooxidation of H2O Molecules existing in the interlayer. Some organic molecules such as amines intercalated in the interlayer were also easily photoelectrochemically oxidized. The photoresponse decreased by the intercalation of some transition metal cations, although alkaline metal cations gave no effect. Consequently it was found that the titanate layered oxide acts as an n-type semiconductor, and that various molecules exiting in the interlayer are photoelectrochemically active.