Enhanced Photodegradation of Organic Pollutants by Carbon Quantum Dot (CQD) Deposited Fe3O4@mTiO2 Nano-Pom-Pom Balls

Highly water dispersible, superparamagnetic carbon quantum dot (CQD) deposited Fe3O4@mTiO(2) pom-pom balls have been prepared by a simple hydrothermal method. The effective deposition of carbon dots expands the light absorption of mTiO(2) from the UV to visible region. The results of photocurrent measurement reveal that an optimum deposition of C-dot at 20 wt % significantly increases the photocurrent density. High surface area and extended conjugation of carbon dots enhance the adsorption of organic pollutants. The active species generated in the photocatalytic system were also detected through trapping of radicals and holes in the presence of various scavengers. In a comparison with a conventional photocatalyst such as Degussa P25, the developed heterojunction shows much higher degradation efficiency for ciprofloxacin, methylene blue, quinalphos, and 4-nitrophenol under visible light. The light upconversion properties of uniformly deposited carbon quantum dots could be a reason for higher visible light catalytic activity of the synthesized magnetically recoverable hybrid photocatalyst.