Effect of Fe on the photocatalytic removal of NOx over visible light responsive Fe/TiO2 catalysts

• Fe/TiO2 catalysts were prepared with co-precipitation, homogeneous precipitation and wet impregnation.
• Fe/TiO2 catalysts prepared with co-precipitation were best for the NO removal.
• Local structure of Fe ions was found to be different in the three series.
• Fe ions substituted the Ti ions of TiO2 was beneficial for the photocatalytic performance.

We synthesized different Fe/TiO2 catalysts and studied the influence of Fe on the structure and performance of Fe/TiO2 as a photocatalyst to remove gaseous NO in air under visible light. The electron paramagnetic resonance results revealed that Fe ions substituted the Ti ions of TiO2 prepared by co-precipitation and homogeneous precipitation method. More Fe ions were incorporated into the crystal lattice of TiO2 prepared by co-precipitation method than that prepared by homogeneous precipitation method. No Fe ions were incorporated into the crystal lattice of TiO2 prepared by conventional wet impregnation method. Furthermore, Fe doping influenced the UV–vis absorption and photoluminescence of TiO2. The higher photocatalytic activity of Fe/TiO2 prepared by co-precipitation method was attributed to the synergistic effects of more visible light absorption and minimum electron hole recombination caused by the Fe ions incorporated into the crystal lattice of TiO2. Density functional theory calculations further confirmed the role of Fe on the electronic structure of TiO2.

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