Low temperature nanocasting of hematite nanoparticles using mesoporous silica molds

Iron oxide (α-Fe2O3) nanoparticles with very small size, high crystallinity, and narrow size distribution were synthesized by infiltration of Fe(NO3)3·9H2O as an oxide precursor into mesoporous silica (SBA-15 and SBA-16) molds using a wet-impregnation technique. High resolution transmission electron microscopy shows that during the hydrothermal treatment of the precursor at 140 °C for 2 days, stable α-Fe2O3 nanoparticles inside the silica pores are formed. Subsequent dissolution of the mesoporous silica molds by NaOH resulted in well dispersed nanoparticles with an average diameter of ~ 4 nm.