Phase and photoelectrochemical behavior of solution-processed Fe2O3 nanocrystals for oxidation of water under solar light

Monodispersed iron-oxide nanocrystals of controlled sizes (5–16nm) were prepared by the thermal decomposition of iron-oleate complex to fabricate photoanode films for photoelectrochemical oxidation of water under simulated solar light. The smallest 5nm particles were made mostly of γ-Fe2O3, but other sizes showed mixed phases with Fe3O4, whose fraction increased with size. Size-dependent photoanodic currents were also observed, showing maximum photocurrent density for 12nm particles. The high photocurrents were attributed to the lowered electron-hole recombination rates for the nanocrystals with the sizes comparable to the hole diffusion length.