It is demonstrated that vertically-aligned titania nanotube planar arrays fabricated by electrochemical anodization using standard potassium-containing electrolytes invariably contain a significant amount of surface-adsorbed potassium ions that enhance the titania water splitting (photoelectrochemical) performance. Synhcrotron-based Near Edge X-ray Absorption Fine Structure (NEXAFS)spectroscopy reveals the strong ionic nature of surface potassium-titania nanotubes through reduction of the external electrical bias needed to produce hydrogen at maximum efficiency. This result implies that the external electrical energy input required per liter of solar hydrogen produced with potassium-adsorbed titania nanotubes is also reduced. Specifically, it is demonstrated that potassium-modified titania nanotubes require about one-thired (0.4) of the electrical energy input in comparison with potassium-free nanotubes to produce the same amount of hydrogen. Tailoring the potassium content may thus be an efficient means to fine-tune the photoelectrochemical response of TiO2 nanotube-based PEC electrodes.
Citation: Journal of Materials Chemistry
Pub Type: Journals
nanotubes, NEXAFS, photoelectrochemical, titania