Green synthesis of reduced graphene oxide/Fe3O4/Ag ternary nanohybrid and its application as magnetically recoverable catalyst in the reduction of 4-nitrophenol

Materials having both magnetic and catalytic properties have shown great potential for practical applications. Here, a reduced graphene oxide/iron oxide/silver nanohybrid (rGO/Fe3O4/Ag NH) ternary material was prepared by green synthesis of Ag on pre-synthesized rGO/Fe3O4. The as-prepared rGO/Fe3O4/Ag NH was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, transmission electron microscopy and energy-dispersive X-ray spectroscopy. rGO sheets were covered with Fe3O4 (8–16 nm) and Ag (18–40 nm) nanoparticles at high densities. The mass percentages were 13.47% (rGO), 62.52% (Fe3O4) and 24.01% (Ag). rGO/Fe3O4/Ag NH exhibited superparamagnetic behavior with high saturated magnetization (29 emu g−1 at 12 kOe), and efficiently catalyzed the reduction of 4-nitrophenol (4-NP) with a rate constant of 0.37 min−1, comparable to those of Ag-based nanocatalysts. The half-life of 4-NP in the presence of rGO/Fe3O4/Ag NH was ca 1.86 min. rGO/Fe3O4/Ag NH could be magnetically collected and reused, and retained a high conversion efficiency of 94.4% after the fourth cycle. rGO/Fe3O4/Ag NH could potentially be used as a magnetically recoverable catalyst in the reduction of 4-NP and environmental remediation.