Lithium Incorporation into Titanium Dioxide Films from a Propylene Carbonate Solution: A Photoelectrochemical Study

Photoelectrochemical behavior of thin-film TiO2 electrodes produced by chemical and electrochemical oxidation of a titanium substrate is studied at potentials corresponding to the domain of active incorporation/extraction of lithium in an LiClO4 solution in propylene carbonate (1.0 V <; E <; 2.5 V vs. Li/Li+) and the inert domain (2.6 V <; E <; 3.6 V). Spectral and current–voltage characteristics are obtained for the photocurrent of TiO2- and Li x TiO2-electrodes, which show n-semiconductor properties, in particular, generate an anodic (hole) photocurrent under illumination. The disappearance of the anodic photocurrent and the onset of a small cathodic photocurrent correlate with the beginning of active incorporation of lithium into the source oxide. The photosensitivity of intercalate Li x TiO2 in the studied domain of spectrum is low and decreases with increasing lithium concentration. A photoeffect is discovered in the long-wave domain of spectrum beyond the limits of intrinsic absorption of a solid. The photocurrent is described by a characteristic exponential spectral curve.