Abstract in English:

Due to the variability of the cation occupancy of octahedral and tetrahedral sites, spinel ferrites and cobaltites are particularly interesting to investigate activity trends in oxidation catalysis. Yet, the preparation of the respective catalyst series remains challenging. We employed pulsed laser defect engineering of CoFe₂O₄ nanoparticles in water to gradually alter the cation occupancy of octahedral and tetrahedral sites by single laser pulses and study its effect on cinnamyl alcohol oxidation. Three CoFe₂O₄ catalysts from different synthesis methods resembling different initial site occupancy were chosen as starting materials. The laser-induced randomization of the cation occupancy was verified by Mössbauer spectroscopy and linearly correlated with the conversion of cinnamyl alcohol while the size and Co : Fe ratio was maintained during laser processing. The study solidifies the importance of octahedral Co³⁺-sites and the feasibility of pulsed laser processing for altering the cation occupancy and related crystallographic defect density in oxidation catalysis.