Metal-free inactivation of E. coli O157:H7 by fullerene/C3N4 hybrid under visible light irradiation

Interest has grown in developing safe and high-performance photocatalysts based on metal-free materials for disinfection of bacterial pathogens under visible light irradiation. In this paper, the C-60/C3N4 and C-70/C3N4 hybrids were synthesized by a hydrothermal method, and characterized by X-ray diffraction (XRD), UV-vis diffuse reflection spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and high revolution transmission electron microscope (HRTEM). The performance of photocatalytic disinfection was investigated by the inactivation of Escherichia coli O157:H7. Both C-60/C3N4 and C-70/C3N4 hybrids showed similar crystalline structure and morphology with C3N4; however, the two composites exhibited stronger bacterial inactivation than C3N4. In particular, C-70/C3N4 showed the highest bactericidal efficiency and was detrimental to all E. coli O157:H7 in 4 h irradiation. Compared to C3N4, the enhancement of photocatalytic activity of composites could be attributed to the effective transfer of the photoinduced electrons under visible light irradiation. Owing to the excellent performance of fullerenes (C-60,C-70)/C3N4 composites, a visible light response and environmental friendly photocatalysts for disinfection were achieved.