Nanostructured iron oxide thin films deposited by RF sputtering as catalysts for the heterogeneous solar photo-Fenton reaction

Nanostructured iron oxide coatings have been deposited by plasma sputtering by different approaches, with and without thermal annealing, with the aim of preparing supported catalysts for solar photo-Fenton. Depending on the experimental conditions explored (O2 content in the feed, annealing or bilayer approach) the phase composition of iron oxide changes and the surface nanostructure as well. The evaluation of methylene blue degradation in photo-Fenton reaction indicates a good performance of the investigated materials. Degradation percentage between 84 and 97% have been obtained in 180 min with a constant reaction rate as high as 18.0 x 10-3 min-1, with the best result for a bilayer sample obtained without thermal annealing. This preliminary investigation highlights that the photoactivity of the coatings is related not only to the content of alpha-Fe2O3, but also to the presence of developed nanostructures on the coating surface, making the material more active. The proposed method for producing supported catalyst based on photo-Fenton reaction is straightforward, and the possibility to reuse the catalyst up to ten reaction cycles is demonstrated.