TiO2 nanotube arrays modified with nanoparticles of platinum group metals (Pt, Pd, Ru): enhancement on photoelectrochemical performance

Highly ordered TiO 2 nanotube arrays (TiO 2 NTs) were synthesized by anodization method using a titanium foil and further modified with nanoparticles ( Ø  = 2~10 nm) of three platinum group metals (that is, platinum, palladium, and ruthenium) through potentiostatic pulsed electrodeposition method to obtain the composite material. Compared with pure TiO 2 NTs, all the three composite samples (M-TiO 2 NTs, M = Pt, Pd, Ru) showed different enhancement effects on the light responses, as well as different photoelectrochemical performances. In this study, the performance of M-TiO 2 NTs, which worked as photoanode and cathode, was investigated. Ru-TiO 2 exhibited the best degradation yield (~ 85.8%) when applied as photoanode under visible light illumination, which indicated the platinum group metal could also be induced under visible irradiation, not just served as the co-catalyst. M-TiO 2 NTs as cathode were evaluated under the hydrogen evolution reaction (HER). The three M-TiO 2 NT electrodes showed an improved efficiency over pure TiO 2 NTs, while Pt-TiO 2 NTs performed even better (without any sacrificial agent) with higher Faradic efficiency than platinum electrode in the photoelectrocatalytic hydrogen production, which could be explained by the uniform and fine metal nanoparticles on the surface of TiO 2 NTs to offer abundant active sites for the reaction. In this paper, TiO2 nanotube arrays loaded with nanoparticles of platinum group metals have been explored on their enhancement of photoelectrocatalytic activity. Platinum group metals served as co-catalyst in the surface of TiO2 nanotubes and show great variations in different reactions.