Enhanced visible light photocatalytic activity of Fe₂O₃ modified TiO₂ prepared by atomic layer deposition

In this work, commercial anatase TiO₂ powders were modified using ultrathin Fe₂O₃ layer by atomic layer deposition (ALD). The ultrathin Fe₂O₃ coating having small bandgap of 2.20 eV can increase the visible light absorption of TiO₂ supports, at the meantime, Fe₂O₃/TiO₂ heterojunction can effectively improve the lifetime of photogenerated electron-hole pairs. Results of ALD Fe₂O₃ modified TiO₂ catalyst, therefore, showed great visible light driven catalytic degradation of methyl orange compared to pristine TiO₂. A 400 cycles of ALD Fe₂O₃ (~ 2.6 nm) coated TiO₂ powders exhibit the highest degradation efficiency of 97.4% in 90 min, much higher than pristine TiO₂ powders of only 12.5%. Moreover, an ultrathin ALD Al₂O₃ (~ 2 nm) was able to improve the stability of Fe₂O₃-TiO₂ catalyst. These results demonstrate that ALD surface modification with ultrathin coating is an extremely powerful route for the applications in constructing efficient and stable photocatalysts.