Influence of the Arrangement of the Octahedrally Coordinated Trivalent Cobalt Cations on the Electrical Charge Transport and Surface Reactivity

The spinel (Co 3 O 4 ) and the perovskite (LaCoO 3 ) oxides are two distinct structures that have in common the trivalent cobalt cations in the octahedral sublattice but in contrasting interconnection geometries. Several properties are directly related to these octahedra, which are edge-connected in the spinel and vertex-connected in the perovskite structure. The electrical charge transport was investigated in both materials to explain the superior conductivity of the perovskite despite the confirmed high mobility barrier. The surface probing indicates the higher reducibility of the spinel, and higher abundance and strength of the basic sites in the perovskite structure. The consequence of the contrasting physicochemical properties of these two materials, edge- and vertex-connected octahedra, on the surface reactivity was discussed in terms of the catalytic efficiency toward the oxidation of CO, aromatics, and alcohols.