Y₂O₃ electrodeposited TiO₂ nanotube arrays as photoanode for enhanced photoelectrochemical water splitting

Y₂O₃ deposited TiO₂ nanotubes (Y-TNTs) are investigated as photoanodes for efficient photoelectrochemical water splitting. Y₂O₃ is electrodeposited on TiO₂ nanotubes for 5–15 min. The physicochemical and optical properties of Y-TNTs reveal that Y₂O₃ anchored on the TNTs enhances the visible light absorption. The Y-TNTs show good photocurrent response compared to pristine TNTs. Y₂O₃ deposition for 10 min on TNTs produces highest photocurrent of 609 μA cm⁻² at 1.23 V_RHE. Presence of Y₂O₃ increases the lifetime of the charge carriers as revealed by the Nyquist plot analysis and Mott-Schottky analysis. Y-TNTs-10 min sample shows 2.75 times higher photoconversion efficiency compared to pristine TNTs. Computational analysis shows that Y–TiO₂ has negative free energy of adsorption for OER intermediates as compared to bare TiO₂ which has positive values. The rare earth metal electrodeposition on TiO₂ nanotubes is another approach to improve the photoelectrochemical water splitting activity without distorting the nanotube structure.