Heterometal modified Fe3O4 hollow nanospheres as efficient catalysts for organic transformations

Iron oxides (e.g. Fe 3 O 4 ) 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 Fe 3 O 4 (M-Fe 3 O 4 ) hollow nanospheres via a two-step solvothermal/annealing method. Due to the uniformly dispersed active heterometal species in the spherical shell of Fe 3 O 4 hollow nanospheres, the as-prepared Pd-Fe 3 O 4 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 Fe 3 O 4 supported metal catalysts reported in literatures. Particularly, Cu-Fe 3 O 4 exhibited 5 times higher activity for benzyl alcohol oxidation compared to that of bare Fe 3 O 4 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.