Photocatalytic hydrogen production from water/methanol solutions over highly ordered Ag–SrTiO3 nanotube arrays

The highly ordered Ag–SrTiO3 nanotube arrays (NTAs) with uniform size were successfully synthesized by a combination of anodic oxidation, hydrothermal process and photocatalytic reduction method. X-ray photoelectron spectroscopy analysis reveals that Ag exists in the form of metallic silver, which is in good agreement with the X-ray diffraction characterization. Moreover, the UV–vis diffuse reflectance spectra indicate that Ag–SrTiO3 NTAs have a strong absorption in the visible region which is attributed to the plasmon resonance of silver nanoparticles. After Ag loading, a further improvement of the photocatalytic activity for hydrogen production was obtained. Based on the above results, a possible electron-hole transfer mechanism was also assumed.