Efficient charge separation of photo-Fenton catalyst: Core-shell CdS/Fe3O4@N-doped C for enhanced photodegradation performance

Effective charge separation and excellent mass transfer are critical for dye photodegradation. Herein, a core-shell cadmium sulfide/ferroferric oxide@nitrogen doped porous carbon (CdS/Fe3O4@NPC) photo-Fenton catalyst was prepared by a facile calcination-hydrothermal method. Fe3O4 core not only is favorable to the catalyst recycle because of its super-paramagnetism, but also serves as the redox mediator for collection and consumption of the electrons from CdS, which will improve the separation rate of the photo-generated charge carriers. What's more, Fe3O4 can work as a Fenton catalyst to activate hydrogen peroxide which is generated in situ by CdS. The porous structure of NPC shell with high conductivity can enhance charge separation and facilitate reactant/product mass transfer, thus promoting holes consumption and impeding the photocorrosion of CdS. Benefiting from its structure and functions, the obtained CdS/Fe3O4@NPC shows wonderful rhodamine B degradation performance (92.0% within 75 min) and still maintains high photo-Fenton catalytic activity after 5 cycles under the visible light irritation. Additionally, the free radical removal experiments show that center dot O-2(-) and center dot OH are the main active substances of catalysis, which confirms the synergistic effect of photocatalysis and Fenton catalysis.