The impact of nanometric Fe2O3 on the magnetic, electronic, and photocatalytic behavior of TiO2@Fe2O3 heterostructures

Abstract

The synthesis method we used enables the homogeneous deposition of both relatively large and small Fe2O3 nanoparticles on the surface of TiO2. SAED analysis shows that TiO2 NCs crystallize in anatase form and Fe2O3 as hematite in all cases. The formation of a TiO2@Fe2O3 heterostructure leads to an increase in photocatalytic activity (in the presence of H2O2) compared to pure titanium and iron oxides. Mössbauer spectra confirm the existence of the hematite structure of Fe2O3 and, together with XPS, the presence of Fe3+ only. Fe2O3 nanoparticles on the surface of TiO2 nanocrystals are in the paramagnetic/superparamagnetic state. Magnetization curves under ZFC and FC conditions also indicate the effect of the size of Fe2O3 particles on the magnetic properties of TiO2@Fe2O3 nanostructures. The magnetic properties of the TiO2@Fe2O3 heterostructure exhibit sensitivity to the size of nanometric Fe2O3 grains. The energies of optical transitions in nanometric Fe2O3 reveal the occurrence of a quantum-size effect. The heterostructures forms a complex structure; on the one hand, at the TiO2 acceptor level associated with the incorporation of Fe3+ into the structure of TiO2 anatase there is present on the other hand, the microstructure differentiation responsible for the occurrence of three optical transitions in Fe2O3.