Iron as modifier of Pd and Pt-based catalysts for sustainable and green processes

This review provides an overview of the synthetic methods used for the preparation of monometallic Pd and Pt metal nanoparticles (NPs) supported on iron oxide and bimetallic Pd-Fe and Pt-Fe systems. The use of iron as a support or as a modifier leads to a change in electronic density on the noble metal, which in turn affects the catalyst activity. In particular, when iron oxide is used as a support the noble metal tends to donate electrons to the support. On the contrary, bimetallic noble metal-Fe NPs show a charge transfer from iron to the noble metal. This behavior occurs both when iron is in contact or strictly closed to the noble metal NPs. The synthetic approach used for the synthesis influences the physico-chemical properties of the final material, thus a focus on the synthetic procedures and the catalyst characterization are provided to elucidate the key factors that influence the exceptional catalytic performances of these materials. Pd-Fe, Pt-Fe bimetallic NPs were selected as representative systems due to their broad use in heterogeneous oxidation and hydrogenation catalytic reactions.