One-pot preparation of ternary reduced graphene oxide nanosheets/Fe₂O₃/polypyrrole hydrogels as efficient Fenton catalysts

Ternary reduced graphene oxide nanosheets (rGSs)/Fe₂O₃/polypyrrole (PPy) hydrogels with Fe₂O₃ nanoparticles (NPs) embedded between rGSs and PPy layer were prepared in one-pot. The ternary hydrogels exhibited an interconnected and porous three-dimensional network with co-existence of macropores and mesopores. Fe₂O₃ NPs uniformly dispersed on rGS surface with the diameter of 8.8 nm. Control experiments were carried out to investigate the roles of components in formation of ternary hydrogels. During heterogeneous Fenton degradation of methylene blue (MB) dyes, the ternary hydrogels exhibited much better removal efficiency than the reference samples, not only because rGSs and PPy layer altered the adsorption, dispersity and diameter of Fe₂O₃ NPs; but also owing to the structural merits of ternary hydrogels. The effects of operating conditions, such as initial MB concentrations, dosages of catalysts and H₂O₂, were carefully investigated. With the help of Fe₂O₃ NPs, ternary rGSs/Fe₂O₃/PPy hydrogels could be easily separated via a magnet. In recycling experiments, they showed superior reusability.