Preparation and photocatalytic activity for water splitting of Pt-Na ₂Ta₂O₆ nanotube arrays

Na₂Ta₂O₆ nanotube arrays were prepared by hydrothermal method from Ta₂O₅ nanotube arrays, obtained by anodization of Ta foils, in Na₂CO₃ solution at 150 °C. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis diffuse reflectance spectra (UV-DRS) and X-ray photoelectron spectroscopy (XPS). Analysis results show that pyrochlore structure Na₂Ta₂O₆ nanotube arrays have been successfully fabricated. The diameters and lengths of Na ₂Ta₂O₆ nanotube arrays are 50 nm and 4 μm, respectively. The photocatalytic hydrogen production activities of the as-synthesized Na₂Ta₂O₆ nanotube arrays are highly dependent on the hydrothermal reaction time and Na₂CO ₃ concentration, optimized reaction parameters are obtained. To further improve the photocatalytic activity for hydrogen evolution, Pt loaded Na₂Ta₂O₆ nanotube arrays are prepared by photochemical reduction method. The Pt loaded samples exhibit much higher activity for hydrogen evolution than pure Na₂Ta₂O ₆ nanotube arrays. Moreover, the photocatalytic hydrogen properties are rather stable.