Controlled charge-dynamics in cobalt-doped TiO 2 nanowire photoanodes for enhanced photoelectrochemical water splitting

In this study, we report for the first time the controlled Co-doping in TiO nanowire (NW) arrays grown on the FTO substrate for highly efficient photoelectrochemical (PEC) water splitting. The Co/TiO and pristine TiO are single crystalline with a tetragonal rutile structure, while the primary peaks were transformed to (0 0 2) with the adding of Co. Compared to pristine TiO NW photoanode, the photocurrent of as-prepared Co/TiO NW arrays electrodes show a higher PEC activity with up to ∼150% of photocurrent density increase under simulated solar radiation. The Co-doping enabled to control the charge dynamics in TiO photoanode and thus can achieve an enhanced photocurrent density. The electrochemical impedance measurement indicates that the density of photogenerated carriers can be significantly increased by the Co doping. The Co/TiO NW photoanodes exhibit high stability in photoelectrochemical conversion and show great potential for a variety of solar energy driven applications.