Facile Construction of g-C₃N₄ Nanosheets/TiO₂ Nanotube Arrays as Z-Scheme Photocatalyst with Enhanced Visible-Light Performance

Semiconductor photocatalysis may be a promising strategy to face energy and environmental issues because it utilizes the solar energy as energy source. The artificially Z-scheme photocatalytic system has attracted special interests owing to its high efficiency and strong redox ability. Graphitic carbon nitride nanosheets (g-C₃N₄ NSs) display prominent performances, which are intensively investigated. Herein, we constructed an all-solid-state Z-scheme photocatalytic system and firstly immobilized g-C₃N₄ nanosheets on TiO₂ nanotube arrays (TNTAs) by a simple method. The microstructures of prepared g-C₃N₄ NSs/TNTAs photocatalyst were characterized by XRD, X-ray photoelectron spectroscopy, SEM and TEM. The features of light absorption, charge separation, and charge transfer were analyzed by UV/Vis diffuse reflectance techniques, photoluminescence spectroscopy, electrochemical atomic force microscopy, and photocurrent measurement. The synthesized g-C₃N₄ NSs/TNTAs samples shows enhanced photocatalytic efficiency for rhodamine B degradation under visible light, which is four times more than that of pure TNTAs. Tetracycline hydrochloride could also be effectively degraded under visible light, which contributes to reducing antibiotic residues in wastewater. Additionally, g-C₃N₄ NSs/TNTAs also possess other advantages such as well long-term stability and easily recyclable properties. A reaction mechanism is also proposed.