Preparation and photoelectrocatalytic activity of ZnO nanorods embedded in highly ordered TiO₂ nanotube arrays electrode for azo dye degradation

In this article, the ZnO nanorods embedded in highly ordered TiO₂ nanotube arrays (ZnO/TiO₂ NR/Ts) electrodes were fabricated through two steps: (1) electrosynthesis of TiO₂ nanotube arrays (TiO₂ NTs) in HF solution by anodization method; (2) followed by cathodic electrodeposition of ZnO embedded in the TiO₂ nanotube arrays. The morphological characteristics and structures of ZnO/TiO₂ NR/Ts electrodes were examined by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) analysis, and UV-vis spectra. The linear-sweep photovoltammetry response on the ZnO/TiO₂ NR/Ts electrode was presented and the photocurrent was dramatically enhanced on the ZnO/TiO₂ NR/Ts electrode, comparing with that on bare TiO₂ NTs electrode. The photocatalytic and photoelectrocatalytic activity of ZnO/TiO₂ NR/Ts electrode was evaluated in degradation of methyl orange (MO) in aqueous solution.