Research progress of LDHs as Fenton reaction catalysts

Fenton reaction utilizes the catalytic reaction of H2O2 and Fe2+ to generate highly active hydroxyl radicals (·OH) quickly to degrade organic compounds without the secondary pollution of by-products, which is widely used in the fields of environmental protection and sewage treatment. However, the difficulty of the regeneration of low-valence metals in the ordinary homogeneous Fenton reaction limits the efficiency of the overall reaction. In addition, the acidic requirements of the reaction system and the introduction of iron ions are not ideal from an environmental perspective. In recent years, layered double hydroxides (LDHs), as a unique layered material, have shown excellent catalytic performance in Fenton reaction and have attracted widespread attention. The active sites of LDHs are usually the metal ions fixed on the solid surface, which can avoid the leaching of metal ions and reduce the pH requirements of the reaction system. Besides, by adjusting the structure of the LDHs layers, a redox cycle of multiple metals can be formed, which promotes the regeneration of the low-valence metals effectively and thus improves the efficiency of the Fenton reaction. This review mainly summarizes the recent progress of LDHs materials as Fenton reaction catalysts. The challenge and prospective trends of LDHs materials as Fenton reaction catalysts are also discussed.