Effect of TiCl4 treatment on the photoelectrochemical properties of LaTiO2N electrodes for water splitting under visible light

A lanthanum titanium oxynitride (LaTiO2N) electrode was studied as a visible-light driven photoelectrode for water splitting. The electrode was prepared by casting a LaTiO2N powder on a fluorine-doped tin oxide glass substrate, followed by calcination under dinitrogen. The as-prepared electrode exhibited an anodic photocurrent based on water oxidation under visible-light irradiation (λ > 420 nm) in an electrolyte (Na2SO4) solution. This current was increased by post-treatment with titanium(IV) chloride (TiCl4) solution. Scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the titanium species introduced by the post-treatment were titanium oxide, and that they were embedded within LaTiO2N particles. Resistance measurements of LaTiO2N electrodes suggested that the increase in the electrode photocurrent after TiCl4 treatment was due to the improvement of inter-particle electron transfer in the LaTiO2N thin film.