Synthesis of a well-dispersed CaFe2O4/g-C3N4/CNT composite towards the degradation of toxic water pollutants under visible light

Herein, we fabricated a ternary photocatalyst composed of CaFe2O4, multiwalled carbon nanotubes (CNTs) and graphitic carbon nitride (g-C3N4) via a simple hydrothermal route. CaFe2O4 acted as a photosensitizer medium and the CNT acted as a co-catalyst, which remarkably enhanced the photocatalytic performances of g-C3N4 towards the degradation of hexavalent chromium (Cr(vi)) and the antibiotic tetracycline (TC) under visible light irradiation. To investigate the morphological and topological features of the photocatalyst, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) analyses were performed. The surface properties and oxidation state of the CaFe2O4/g-C3N4/CNT composite were determined by X-ray photoelectron spectroscopy (XPS). The recombination rate of the charge carriers and the band gap values of the as-synthesized catalysts were analyzed by photoluminescence spectroscopy (PL) and diffused reflectance spectroscopy (UV/Vis DRS) studies, respectively. Besides the degradation reactions, the high hydrogen production rate of 1050 mu mol h(-1) under visible light using the CaFe2O4/g-C3N4/CNT composite loaded with 5 wt% CNT was observed. The superior photocatalytic performances of the CaFe2O4/g-C3N4/CNT composite can be ascribed to the effective heterojunction formed between g-C3N4 and the CaFe2O4 matrix, in which the CNT act as a conducting bridge in the system, promoting the production of photoinduced charge carriers in the semiconductor system. Finally, the plausible photocatalytic mechanism towards the degradation of pollutants and hydrogen production was discussed carefully.