FIGURE
1 Schematic diagram of the synthesis of
Fe3O4@C and adjustment of the surface
structure by controlling relative distance to the magnet. The inserted
image shows light reflection inside the spine arrays.
2. Results and Discussion
2.1. Characterization of carbon-coated nanoparticles
The carbon-coated nanoparticles were synthesized by a typical
hydrothermal method. After coating with a carbon layer, the
carbon-coated nanoparticles remain granular and have a certain
dispersion (Figure S2a-b). In the experiment, the thickness of carbon
layer was changed by adjusting the amount of glucose as carbon source.
As TEM images shown in Figure 2a-c,
Fe3O4@C had a carbon layer at the
thickness of ~15 nm. While, as 2 g of glucose was used
in preparation, the thickness of carbon layer of
Fe3O4@tC was up to ~28
nm. Following the particle size distribution in Figure 2d, the major
particle sizes of Fe3O4,
Fe3O4@C and
Fe3O4@tC were about 666 nm, 691 nm and
715 nm, respectively. In comparison to the pristine magnetic
nanoparticle, Fe3O4@C and
Fe3O4@tC revealed increases in diameter
of 25 nm and 49 nm, which were generally consistent with the results in
TEM images.