Photoelectrochemical study of a spinel-type titanomagnetite

Abstract The electrical and photoelectrical properties of spinel-type titanomagnetite Fe 3− x Ti x O 4 with x = 0.964 have been investigated. The electrical conductivity involves a mechanism by which electrons in octahedral sites hop from the Fe 2+ : t 2 gβ level to the Fe 3+ : t 2 gβ level, despite the observed positive value of the Seebeck coefficient. The photoelectrode shows significant anodic photocurrent and negative flatband potential which are evidence of an n -type character. The flatband potential determined from impedance measurements is found to be close to that of n -type α-Fe 2 O 3 . In addition, the photocurrent is due to indirect electronic transitions occurring at 2.00 and 2.39 eV. A proposed energy level diagram suggests that the photoresponse results from either iron-iron or (and) iron-titanium charge transfers.