Electrochemical Method for Synthesis of a ZnFe₂O₄/TiO₂ Composite Nanotube Array Modified Electrode with Enhanced Photoelectrochemical Activity

Abstract

Abstract An electrode with intimate and well‐aligned ZnFe 2 O 4 /TiO 2 composite nanotube arrays is prepared via electrochemical anodization of pure titanium foil in fluorine‐containing ethylene glycol, followed by a novel cathodic electrodeposition method. The deposition of ZnFe 2 O 4 is promoted in the self‐aligned, vertically oriented TiO 2 nanotube arrays but minimized at the tube entrances. Thus, pore clogging is prevented. Environmental scanning electron microscopy, energy‐dispersive X‐ray spectra, high‐resolution transmission electron microscopy, X‐ray diffraction patterns, and X‐ray photoelectron spectroscopy indicate that the as‐prepared samples are highly ordered and vertically aligned TiO 2 nanotube arrays with ZnFe 2 O 4 nanoparticles loading. The TiO 2 nanotubes are anatase with the preferential orientation of <101> plane. Enhanced absorption in both UV and visible light regions is observed for the composite nanotube arrays. The current–voltage curve of ZnFe 2 O 4 ‐loaded TiO 2 nanotube arrays reveals a rectifying behavior. The enhanced separation of photoinduced electrons and holes is demonstrated by surface photovoltage and photocurrent measurements. Meanwhile, the photoelectrochemical investigations verify that the ZnFe 2 O 4 /TiO 2 composite nanotube array modified electrode has a more effective photoconversion capability than the aligned TiO 2 nanotube arrays alone. In addition, the photoelectrocatalytic ability of the novel electrode is found enhanced in the degradation of 4‐chlorophenol.