Tailoring Mesoporous γ-Al2O3 Properties by Transition Metal Doping: A Combined Experimental and Computational Study

Well crystallized gamma alumina (γ-Al2O3) with high thermal stability is as an important catalyst support. A series of first row transition metal (TM) doped aluminas with ordered mesoporous structures and homogeneous distribution of TM in the bulk structure has been synthesized by a one-pot method. The structures are studied by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM), while the electronic properties are explored by X-ray photoelectron spectroscopy (XPS), valence band XPS, and UV–vis spectra. To explore the influence of TM dopants on atomistic properties (bond length, charge state, band edge, and redox properties) of γ-Al2O3, the cation distribution of TM dopants is studied in detail by combining experiments and density functional theory (DFT) calculations. The cooperative effect of TM dopants and intrinsic defects in γ-Al2O3 induces a doping mechanism distinct from that in other spinel oxides; the concentration of Al vacancies (VAl) decreases with increasing atomic number of the TM dopant as a result of charge compensation effects. Such variation could be used to tailor the properties and alter the reactivity of γ-Al2O3.