Solid-State Dispersions of Platinum in the SnO(2) and Fe(2)O(3) Nanomaterials

The dispersion of platinum (Pt) on metal oxide supports is important for catalytic and gas sensing applications. In this work, we used mechanochemical dispersion and compatible Fe(II) acetate, Sn(II) acetate and Pt(II) acetylacetonate powders to better disperse Pt in Fe(2)O(3) and SnO(2). The dispersion of platinum in SnO(2) is significantly different from the dispersion of Pt over Fe(2)O(3). Electron microscopy has shown that the elements Sn, O and Pt are homogeneously dispersed in α-SnO(2) (cassiterite), indicating the formation of a (Pt,Sn)O(2) solid solution. In contrast, platinum is dispersed in α-Fe(2)O(3) (hematite) mainly in the form of isolated Pt nanoparticles despite the oxidative conditions during annealing. The size of the dispersed Pt nanoparticles over α-Fe(2)O(3) can be controlled by changing the experimental conditions and is set to 2.2, 1.2 and 0.8 nm. The rather different Pt dispersion in α-SnO(2) and α-Fe(2)O(3) is due to the fact that Pt(4+) can be stabilized in the α-SnO(2) structure by replacing Sn(4+) with Pt(4+) in the crystal lattice, while the substitution of Fe(3+) with Pt(4+) is unfavorable and Pt(4+) is mainly expelled from the lattice at the surface of α-Fe(2)O(3) to form isolated platinum nanoparticles.