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

Abstract

Abstract In this work, novel materials comprising three-dimensional flower-like αFeOOH 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 αFeOOH. 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 αFeOOH 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 αFeOOH and the CQDs, which facilitated the rapid interfacial transfer of photogenerated electrons from αFeOOH to CQDs and enhanced the absorption of photons under visible light irradiation. Radical quenching experiments and electron spin resonance analysis demonstrated that OH and O2− 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.