Morphology and structure of FeCo/GC@MSS and PMA@FeCo/GC@MSS. TEM images of (a) FeCo/GC@MSS and (b) PMA@FeCo/GC@MSS (Insets are higher magnification images.). (c) TEM image of FeCo/GC nanocrystals (Upper inset is the electron diffraction pattern. Lower inset is the EDX spectrum. Copper is from the TEM grids.) (d) X-ray diffraction patterns.