HIGH PHOTOCURRENT QUANTUM YIELDS IN SHORT WAVELENGTHS FOR NANOCRYSTALLINE ANATASE-TYPE TIO2 FILM ELECTRODES COMPARED WITH THOSE FOR RUTILE-TYPE

Photoelectrochemical activity of nanocrystalline TiO2 film electrodes prepared by use of various TiO2 particles has been studied comparative ly. It is confirmed that the photocurrent (or photoactivity) for anata se-type TiO2 is in general higher than that for the rutile-type. The p hotocurrent quantum yield (eta(pc)) for anatase-type TiO2 is nearly eq ual to that for rutile-type in long wavelengths but increases more and more with decreasing wavelength in contrast to the eta(pc) for rutile -type, and thus the eta(pc) for anatase-type becomes much higher than the eta(pc) for rutile-type in short wavelengths around 300 nm, indica ting that the high photoactivity for anatase-type TiO2 is due to this high eta(pc) in short wavelengths. There are some discussions on the r easons for the high eta(pc) for anatase-type TiO2 in short wavelengths , including the possibility of contribution of hot electrons or holes in the TiO2 film.