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

Abstract

Highly ordered TiO2 nanotube arrays (TiO2 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 TiO2 NTs, all the three composite samples (M-TiO2 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-TiO2 NTs, which worked as photoanode and cathode, was investigated. Ru-TiO2 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-TiO2 NTs as cathode were evaluated under the hydrogen evolution reaction (HER). The three M-TiO2 NT electrodes showed an improved efficiency over pure TiO2 NTs, while Pt-TiO2 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 TiO2 NTs to offer abundant active sites for the reaction.