Effect of Heterojunction on the Behavior of Photogenerated Charges in Fe3O4@Fe2O3 Nanoparticle Photocatalysts

The behavior of photogenerated charges in the Fe3O4@Fe2O3 core/shell nanoparticles with high photocatalytic activity have been investigated by surface photovoltage (SPV) spectroscopy and transient photovoltage (TPV) measurements. The single-phase Fe3O4 and Fe2O3 particles as references have been investigated simultaneously. The results demonstrate that the junction formation in the Fe3O4@Fe2O3 nanoparticles significantly affects the separation, transport, and recombination of photogenerated charges and even changes the transport direction and recombination velocity. And the mechanisms here have been discussed in detail. These results are helpful in understanding the photoelectric process of nanoscaled materials with the heterojunction structures and further utilizing the photoelectric materials and devices.