Fabrication of cadmium indium sulfide/cadmium sulfide/polyoxo-titanium cluster composite nanofibers with enhanced photocatalytic activity for nitrite degradation

Abstract

Photocatalytic removal of nitrite is a convenient and green method. Photocatalytic technology has been limited, however, by its light absorption range and unsuitable conduction and valence bands, which affect the photocatalytic efficiency and nitrogen selectivity. In this work, we synthesized a cadmium indium sulfide/cadmium sulfide/polyoxo-titanium cluster composite nanometer photocatalyst with a visible light response, and further fixed the photocatalyst to fibers to form electrospun film. The samples were characterized using direct reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, Fourier-transform infrared spectroscopy, N2 adsorption–desorption isotherms, and the transient photocurrent response. The photocatalytic activity of the prepared photocatalyst was evaluated based on the transformation of nitrite under simulated sunlight. The photocatalytic results showed that the nitrite conversion rate was as high as 98% within 2 h and had about a 63% selectivity of nitrogen. The combination of CdS and Cdln2S4 better captured visible light and could be adjusted to an appropriate oxidation–reduction potential energy after loading with polyoxo-titanium clusters. Subsequently, the results of cycling experiments indicated that the Cdln2S4/CdS/polyoxo-titanium clusters composite nanofibers maintained a fairly consistent photocatalytic performance. The effects of electron and hole scavengers were investigated and the possible photocatalytic mechanism was elucidated by studying the products during the photocatalytic degradation.