Simple synthesis of magnetic mesoporous FeNi/carbon composites with a large capacity for the immobilization of biomolecules

An easy co-impregnation method has been developed to synthesize magnetic mesoporous FeNi alloy/carbon composites with an ordered hexagonal structure. Furfuryl alcohol and metal nitrates were used as the carbon and magnetic particle precursors and were impregnated into the silica template in one step using a simple ethanol solution of furfuryl alcohol and metal nitrates. Compared to the co-casting route with two-step impregnation, the co-impregnation makes the synthesis simpler and eliminates the difficult second impregnation step. The mesoporous FeNi/carbon composites obtained have large surface areas, large pore volumes and a bimodal pore size distribution. The FeNi alloy nanoparticles were well dispersed in the mesoporous carbon walls. The composites exhibit excellent superparamagnetic behavior and the saturation magnetization strength can be adjusted from 3.4 to 5.7 emu/g by increasing the content of alloy. Such bimodal mesoporous composites show a large immobilization capacity for the biomolecules of cytochrome c (up to 732 mg/g) and lysozyme (up to 790 mg/g).