Engineering controllable oxygen vacancy defects in iron hydroxide oxide immobilized on reduced graphene oxide for boosting visible light-driven photo-Fenton-like oxidation

Visible light-driven photo-Fenton-like technology is a promising advanced oxidation process for water remediation, while the construction of effective synergetic system remains a great challenge. Herein, iron hydroxide oxide (a-FeOOH) with controllable oxygen vacancy defects were engineered on reduced gra-phene oxide (rGO) nanosheets (named as OVs-FeOOH/rGO) through an in-situ redox method for boosting visible light-driven photo-Fenton-like oxidation. By adjusting the pH environment to modulate the redox reaction kinetics between graphene oxide (GO) and ferrous salt precursors, the oxygen vacancy concen-tration in a-FeOOH could be precisely controlled. With optimized oxygen vacancy defects obtained at pH 5, the OVs-FeOOH/rGO displayed superior photo-Fenton-like performance for Rhodamine B degradation (99% within 40 mins, rate constant of 0.2278 mg-1 L min-1) with low H2O2 dosage (5 mM), standing out among the reported photo-Fenton-like catalysts. The catalyst also showed excellent reusability, general applicability, and tolerance ability of realistic environmental conditions, which demonstrates great potential for practical applications. The results reveal that moderate oxygen vacancy defects can not only strengthen absorption of visible light and organic pollutants, but also promote the charge transfer to simultaneously accelerate the photogenerated electron-hole separation and Fe(III)/Fe(II) Fenton cycle, leading to the remarkable photo-Fenton-like oxidation performance. This work sheds light on the controllable synthesis and mechanism of oxygen vacancy defects to develop efficient photo-Fenton-like catalysts for wastewater treatment. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study presents a visible light-driven photo-Fenton-like oxidation process using iron hydroxide oxide with controllable oxygen vacancy defects on reduced graphene oxide nanosheets. The optimized catalyst exhibited superior performance for Rhodamine B degradation with low H2O2 dosage, and showed excellent reusability and applicability. The results highlight the importance of moderate oxygen vacancy defects in enhancing light absorption, organic pollutant removal, and charge transfer, providing insights for the development of efficient photo-Fenton-like catalysts for wastewater treatment.