Effects of transition metal doping on surface properties and resistance to Cl− adsorption of α-Al2O3

Abstract Under the aqueous environment simulated by VASPsol, structures and work functions of surfaces, adsorption behavior of Cl− on the pure α-Al2O3 (0001) and fourth period transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped α-Al2O3 (0001) slabs have been calculated by Vienna Ab-initio Simulation Package (VASP) based on density functional theory (DFT), which ultimately affect the pitting resistance of the target surface. The results evidence that the interlayer spacing of the first and the second atomic layers and characteristic Al-O bond lengths of doped surfaces showed a trend of increasing first and then decreasing with the incremental nuclear charges of doped atoms, which is contrary to the change of work functions and the adsorption energy of Cl− on the corresponding surfaces. These changes are correlative and essentially depend on the variations of the surface charge distribution and surface reactivity. The doping of Sc, Ti, V, Cr, Mn, Fe, Co and Ni is proved to reduce the stability of the Al2O3 surface and makes it easier for Cl− to adsorb on the surface. The doping of Cu and Zn increases the minimum adsorption energy of Cl− on the surface by 0.07 and 0.09 eV, while the surface reactivity was not reduced. The loosening of the upper structure and the decrease of work function are the precursors of surface deterioration.