Fluorine-doped titanium dioxide nanorod arrays for efficient photoelectrochemical water splitting

TiO2 is a well-known photocatalyst due to its excellent photocatalytic activity, low cost, and stability. However, its practical applications are limited by its poor charge transport and wide bandgap. In this study, F-doped TiO2 nanorod arrays were synthesized using a simple chemical bath annealing method, which resulted in significantly improved properties. Among the samples, 0.05F-T(F-doped TiO2 nanorods) exhibited the best performance, with a photocurrent of 7.34 mA/cm2 at 1.8 V vs. reversible hydrogen electrode (RHE), which is 4.61 times higher than that of pure TiO2 nanorods (1.59 mA/cm2). Incident photon-to-current efficiency measurements showed prominent photocurrent responses in the 325-375 nm range and a slight redshift toward the visible region around 425 nm, indicating improved light absorption. The electron-hole separation efficiency was enhanced, and bandgap and flat-band potential measurements confirmed the optimization of the energy band structure. The photoelectrochemical performance for water splitting was also evaluated, with 0.05F-T achieving the highest hydrogen production of 842.28 µmol/cm2 in 5 h at 1.8 V vs. RHE, which is 6.58 times higher than that of pure TiO2 (128.05 µmol/cm2). These results demonstrate that F-doped TiO2 nanorods are promising for enhancing photocatalytic hydrogen production. Highlights 1. A simple wet chemical soaking method introduces the Fluoride (F) element into the TiO2 lattice. 2. F element doping changes the lattice spacing of TiO2 and optimizes the band structure. 3. The doping of the F element causes a red shift in the wavelength of TiO2 light absorption. 4. Efficient photoelectrochemical water splitting achieved by F-doped TiO2 nanorods.