Flower-like FeOOH hybridized with carbon quantum dots for efficient photo-Fenton degradation of organic pollutants

In this work, novel materials comprising three-dimensional flower-like alpha FeOOH with abundant active edges hybridized with carbon quantum dots (CQD@FeOOH) were fabricated via a facile and environmentally friendly two-step process including an electrochemical etching method followed by a urea/ethanol solution cooperating mediated method. CQD@FeOOH exhibited remarkable degradation performance toward refractory phenol in a synergic photocatalytic/Fenton system, with a rate constant (k) 2.8 times higher than that of pristine alpha FeOOH. Moreover, the k value of CQD@FeOOH as a heterogeneous photo-Fenton catalyst was 12.6 and 3.1 times than those of CQD@FeOOH as photocatalysis and Fenton catalysis, respectively. The hybrid materials were characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques to prove that carbon quantum dots (CQDs) were successfully modified on alpha FeOOH to form Fe-O-C bonds. The electrochemical impedance spectra, transient photocurrent performance, photoluminescence spectra, and other photoelectric performance analyses confirmed the strong interaction between alpha FeOOH and the CQDs, which facilitated the rapid interfacial transfer of photogenerated electrons from alpha FeOOH to CQDs and enhanced the absorption of photons under visible light irradiation. Radical quenching experiments and electron spin resonance analysis demonstrated that (OH)-O-center dot and O-center dot(2)- are the main active species for the synergic photo-Fenton degradation. Furthermore, CQD@FeOOH maintained high catalytic activity, high crystallinity, and extremely low iron leaching during repeated experiments. By optimizing degradation conditions, it was found that a low concentration of H2O2 and a wide pH range could maintain high catalytic performance. This work presents a feasible strategy to design and fabricate heterogeneous photo-Fenton catalysts for the removal of organic pollutants.

Automated summary

In this study, CQD@FeOOH material was prepared using a simple and environmentally friendly two-step process, exhibiting remarkable degradation performance in a synergic photocatalytic/Fenton system; characterization techniques confirmed the material structure and photoelectric performance features; high catalytic activity was maintained through optimization of conditions.