A novel method for the preparation of Co Schiff-base functionalized MgAl layered double hydroxides

Abstract

In order to immobilize neutral or positive metal complexes on layered double hydroxides (LDHs) and increase the amount of immobilized metal complexes, a novel strategy for the preparation of metal complex functionalized LDHs is proposed. This strategy involves exfoliating glycine-intercalated MgAl LDH in formamide under an ultrasound treatment, and then grafting silylated metal complexes on MgAl LDH nanosheets, as exemplified by immobilization of Co Schiff-base on MgAl LDHs. The prepared hybrids were characterized by XRD, AFM, FT-IR, TG, N2 adsorption–desorption and ICP techniques and their catalytic performances were investigated in H2O2 decomposition and styrene epoxidation with O2. The results showed that the hybrid prepared by this strategy had higher Co Schiff-base loading than the sample prepared by directly grafting silylated Co Schiff-base on glycine-intercalated MgAl LDHs due to the more accessible grafting sites on the exfoliated MgAl LDH nanosheets. Additionally, it was found that the grafted complexes could effectively impede the restack of LDH nanosheets after removal of the solvent. Thus, the prepared hybrid exhibited higher surface area and more accessible active centers, which made the prepared hybrid exhibit high catalytic activity in H2O2 decomposition and styrene epoxidation with O2. This work gives us a new way to prepare LDH hybrids functionalized with various metal complexes.