“… 21,22 Unfortunately, other characteristic diffraction peaks of anatase-type TiO 2 were not observed, which is possibly due to the limited thickness of the prepared film. 23 In addition, there was no characteristic peak of Y oxide, indicating that TiO 2 was the main component of the film layer on the electrode surface. This phenomenon may be caused by the fact that trace Y ions entered the TiO 2 lattice interstitially or via displacement, instead of forming an ordered lattice structure.…”