Yolk@shell nanoreactor for the heterogeneous Fenton reaction: a review of recent progress

Abstract

The heterogeneous Fenton reaction is a promising technology to non-selectively degrade organic pollutants, providing a feasible solution to environmental problems. However, the essential issue in the Fenton reaction is the design of highly efficient catalysts, and yolk@shell structures are usually employed as a nanoreactor to boost the activation efficiencies of H₂O₂ (or peroxymonosulfate (PMS)). Typically, a yolk@shell nanoreactor is constructed from a hollow shell and a movable core, which can transfer the Fenton reaction from the bulk solution to the internal cavity. Benefiting from the confinement effect, the chance of collision among various reactants is increased, the degradation rate is accelerated, H₂O₂ (or PMS) utilization efficiency is boosted, the environmental tolerance of catalysts is improved, and metal leaching is lowered. Thus, the yolk@shell nanoreactor provides an ideal platform for the heterogeneous Fenton reaction. In addition, many methods could be adopted to tailor the yolk@shell nanoreactor for better catalytic performance, and this inspired researchers to design nanoreactors with optimized compositions and novel structures. At present, many reviews on either the preparation and application of yolk@shell nanoreactors or the recent development of heterogeneous Fenton reactions are reported; however, strategies to improve the Fenton reaction based on yolk@shell nanoreactors have not been discussed in detail. This review illustrated the recent progress on yolk@shell nanoreactors for heterogeneous Fenton reactions and provided comprehensive information on catalyst design, catalytic performance, catalytic mechanisms, catalyst advantages, and catalyst improvement methods, aiming at developing catalysts with better performance.