New homogeneously doped Fe(III)–TiO2 photocatalyst for gaseous pollutant degradation

We report on photocatalytic activity of new homogeneously Fe(III)-doped TiO2 nanocoatings. The material is prepared in a two-stage process including (1) oxo-TiO2 nanoparticles nucleation, doping by iron(acetylacetonate)3 and reactive deposition on glass substrates in a sol–gel micromixing reactor and (2) thermal treatment. The photocatalytic test of the nanocoatings is conducted on ethylene degradation in a continuous-flow fixed bead reactor. The catalyst shows the best performance at Fe/Ti molar ratio of 0.005 at.%, which is explained by a competition between VB-hole localisation on Fe3+ and its annihilation on Fe2+. The proposed model permits an estimation of the localisation distance of the CB-electron in anatase TiO2 after a photoexcitation and defines the optimal size for the nanoparticulate TiO2 photocatalyst to be ∼8 nm.

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► Fe–TiO2 photocatalyst made in micromixing reactor has higher activity than pure TiO2.
► Fe–TiO2 photocatalyst has best activity at 0.005 at.% doping.
► By-products formation causes slow transient regime of ethylene conversion.
► First order kinetics are obtained with a continuous flow reactor.
► CB electron localisation model allows defining an optimal particle size of ≈8 nm.