Preparation and characterization of Ag deposited and Fe doped TiO2 nanotube arrays for photocatalytic hydrogen production by water splitting

Abstract In this paper, highly ordered Fe 3+ -doped TiO 2 nanotube arrays (Fe/TiO 2 NTs) were successfully fabricated by the electrochemical anodic oxidation of pure titanium in an NH 4 F electrolyte solution containing iron ions. Then Ag nanoparticles (Ag NPs) were assembled in Fe/TiO 2 NTs by microwave-assisted chemical reduction (Ag–Fe/TiO 2 NTs). The morphology, structure and composition of the as-prepared nanotube arrays were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence spectrum (PL), UV–vis absorption spectrum (UV–vis), and Raman spectrum, respectively. Compared with pure TiO 2 , Ag deposited and Fe doped TiO 2 showed higher visible light absorption activity and lower electron–hole pair recombination rate. The results showed that Fe 3+ was successfully introduced into the nanotube arrays. It also indicated that Ag NPs were well dispersed on the surface of Fe/TiO 2 NTs with metallic state, which can enhance the visible absorption of TiO 2 NTs based on the local surface plasmon resonance effect (LSPR) of Ag NPs. The photocatalytic activity of Ag–Fe/TiO 2 NTs was evaluated through the experiment of water splitting. Average maximum H 2 production rate through water splitting was 1.35 μmol/(cm 2  h) with using 0.2 mM Ag–0.3 mM Fe/TiO 2 NTs as catalyst. At last, the mechanism of H 2 production by water splitting under visible light irradiation was also proposed.