Preparation of C@CuNi/TiO2 with a local surface plasmon resonance for photocatalytic degradation of organic dyes and antibiotics under visible light irradiation

A composite photocatalyst with carbon-coated CuNi nanoparticles-loaded TiO2 nanotubes (C@CuNi/TiO2) was synthesized via a microwave hydrothermal alkali stripping method combined with subsequent in-situ carbothermal reduction. The structure, morphology, and surface chemical composition were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The findings demonstrate that the microwave hydrothermal alkali peeling enables the formation of a three-dimensional C@CuNi/TiO2 composite structure. The results of transient photocurrent response (i-t) and electrochemical impedance spectroscopy under visible light demonstrate that C@CuNi/TiO2 exhibits a reduced rate of electron-hole recombination and lower surface resistance compared to C@TiO2, C@Cu/TiO2, and C@Ni/TiO2. After a two-hour exposure to visible light, the composite photocatalyst C@CuNi/TiO2, featuring a molar ratio of 2 % CuNi nanoparticles to TiO2 nanotubes, exhibited remarkable degradation activity towards organic dyes (Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO)), as well as antibiotics (tetracycline (TC) and levofloxacin (LVFX)). After 5 cycles of photocatalytic reaction, the photodegradation activity of RhB remained above 79 %. It is indicated that CuNi nanoparticles effectively trap and enrich photoelectrons through the photoexcitation of TiO2 nanotubes. Additionally, the local surface plasmonic resonance (LSPR) effect of CuNi nanoparticles reduces the recombination rate of photogenerated electron/hole and the electron transport resistance in the composite photocatalyst, thereby enhancing its overall photocatalytic activity.