Maghemite, γ-Fe2O3, nanoparticles preparation via carbon-templated solution combustion synthesis

High surface area maghemite, γ-Fe2O3, nanoparticles were prepared via carbon-templated solution combustion synthesis, which is a two-step approach. Step one involves the combustion synthesis of maghemite nanoparticles embedded in an amorphous carbon matrix, by using a fuel rich reaction mixture of triethylenetetramine and iron nitrate. Step two consists of residual carbon removal by treating the previously-obtained composite precursor with hydrogen peroxide, which releases the maghemite nanopowder. This approach avoids carbon removal by thermal treatment, thus preserving the nanometric size of maghemite nanoparticles (8-12 nm), yielding a high specific surface area of 191.9 m2/g. At the same time, the final maghemite nanoparticles presented a superparamagnetic behavior and a saturation magnetization of 26.2 emu/g, in relation to the small particle size.