Heterometal modified Fe3O4 hollow nanospheres as efficient catalysts for organic transformations

Iron oxides (e.g. Fe3O4) are ideal support materials for catalytic organic transformations owing to their sufficient natural abundance, excellent thermal stability and magnetic recycling property. Herein, we report the synthesis of active heterometal (M = Pd, Cu) modified Fe3O4 (M-Fe3O4) hollow nanospheres via a two-step solvothermal/annealing method. Due to the uniformly dispersed active heterometal species in the spherical shell of Fe3O4 hollow nanospheres, the as-prepared Pd-Fe3O4 catalyst exhibits remarkable catalytic activity toward 4-nitrophenol reduction with a turnover frequency of 145 min−1, and shows excellent stability and magnetic recyclability. The catalytic efficiency surpasses most of the similar Fe3O4 supported metal catalysts reported in literatures. Particularly, Cu-Fe3O4 exhibited 5 times higher activity for benzyl alcohol oxidation compared to that of bare Fe3O4 synthesized by the same procedure. An impressive conversion of 49.66% and an outstanding selectivity of 100% can be achieved. Moreover, the positive effects of Pd or Cu elements on the 4-NP molecule adsorption were further confirmed via both experimental results and theoretical studies. Our work demonstrate that the activity boost of iron oxides by heterometal modification is a promising strategy for performance improvement.