The conventional Fenton reaction has played a vital role in the degradation of pollutants. However, this reaction is prone to forming iron mud, which causes secondary pollution. Additionally, most of the Fenton systems are in homogeneous forms and suffer from intrinsically short lifetimes, hydroxyl radicals that have short diffusion distances (center dot OH) and non-recyclability. Herein, using magnetic composites (Fe3O4@SiO2) as the carrier and vanadium oxide quantum dots (VO(x)QDs) as the catalyst, we developed a renewable, heterogeneous, magnetic Fenton-like system for dye degradation in polluted wastewater. The VO(x)QDs of less than 10 nm showed large specific surface areas, enhanced surface-exposed active atoms, and low toxicity, which are favourable for developing an efficient Fenton-like system. In addition, owing to the electrostatic adsorption between the as-prepared catalyst and the dye molecules, the distance for center dot OH sterilization and decolorization can be significantly reduced, overcoming the shortcomings of the short oxidation distance of center dot OH. Accordingly, the degradation of dyes can be achieved in five seconds. Furthermore, the catalysts can be effectively separated and recycled based on their magnetic features, while the secondary pollution from both the catalysts and the incompletely degraded dye molecules into the environment can be avoided. In addition, the Fe3O4@SiO2 is able to maintain a superior morphology, and the composite material (VO(x)QDs/Fe3O4@SiO2) maintains more than 90% of the degradation effects even after eight repeated tests. (C) 2020 Elsevier Inc. All rights reserved.