Yolk-shell magnetic hydrogel Fe3O4@P(DVB-co-MAA)@Ag composite microspheres for enhanced catalytic reduction of nitroaromatics

In this study, yolk-shell magnetic hydrogel microspheres loaded with silver nanoparticles (Fe 3 O 4 @P(DVB-co-MAA)@Ag) were innovatively constructed for efficient catalytic reduction of nitroaromatic compounds. First, hollow P(DVB-co-MAA) microspheres were prepared as shell. Fe 3 O 4 magnetic nanoparticles were successfully deposited into the microspheres as yolk through the decomposition of metal-organic precursor salts in high-temperature organic solvents. The EM images shows that Fe 3 O 4 @P(DVB-co-MAA) microspheres consist of a magnetic core, an intermediate void layer, and a hydrophilic hydrogel shell, demonstrating a unique multilayered structural feature. Then, highly active silver nanoparticles were uniformly loaded onto the hydrogel shell surface using the thermal co-reduction method. Catalytic results demonstrated that the yolk-shell material showed significantly enhanced activity toward the reduction of 4-nitrophenol (4-NP) and 2-nitroaniline (2-NA), compared to the core-shell structured composite microspheres. The catalytic parameters were 65.44 s⁻¹ g⁻¹ and 46.44 s⁻¹ g⁻¹ , respectively. Remarkably, the composite retained over 85 % catalytic efficiency after five cycles of use and achieved rapid magnetic separation within 20 s under an external magnetic field.