Synthesis of magnetic carbon nanodots for recyclable photocatalytic degradation of organic compounds in visible light

Abstract

In this study, magnetic carbon nanodots (C-dots) were synthesized by connecting C-dots and magnetic Fe3O4 nanoparticles (so called magnetic C-dots) in seeking to understand the photocatalytic activity under visible light and the recyclable ability in wastewater treatment. All of the samples were synthesized by bottom-up procedure at reaction temperatures (Tr) of 140 °C and 180 °C with different reaction times (tr = 0–18 h). The results indicated that the C-dots gradually attached to Fe3O4 nanoparticles with the increase of tr at Tr = 140 °C, but suddenly approached saturation adsorption on Fe3O4 particles at Tr = 180 °C. Microstructural images confirmed that magnetic Fe3O4 nanoparticles were surrounded by C-dots 5–10 nm in size. Optical properties illuminated that magnetic C-dots presented a red-shifted emission at λ = 300–450 nm attesting to their photocatalytic ability in visible light. In this study, a higher extent of degradation of the dye was noted in a larger amount of C-dots on a Fe3O4 nanoparticle surface. Methylene blue (MB) concentration can be decreased by 83% within 30-min visible light irradiation. A recyclability test evidenced that the magnetic C-dots can further photodegrade large MO concentrations by at least 10-fold or more. Therefore, magnetic C-dots exhibit good degradation ability for MB under visible light, and could be easily recycled by applying a magnetic field after photodegradation, as shown in this study.