Preparation of nanoporous micrometer-scale hematite particles by a forced hydrolysis reaction in the presence of polyethylene glycol

The effect of poly(ethylene glycol) (PEG) on the formation of spherical hematite particles from a forced hydrolysis reaction in acidic FeCl3 solution was examined. Spherical hematite particles were precipitated under all of the conditions studied, and the diameters of the particles increased from 400 to 1500 nm (1.5 mum) with increasing PEG concentration. The rate of phase transformation from beta-FeOOH to hematite was decreased considerably at higher PEG concentrations as a result of the adsorption of PEG onto both beta-FeOOH and primary polynuclear particles. The hematite particles formed with PEG were hydrohematite with a crystal lattice distortion, and they exhibited a polycrystalline nature. The nanoporous hematite particles were produced in the presence of PEG acting as a prominent templating agent. This study indicates that the forced hydolysis reaction in the presence of PEG is a successful and simple route for producing micrometer-scale nanoporous hematite particles.