Modification of the Oxidative Power of ZnO(1010) Surface by Substituting Some Surface Zn Atoms with Other Metals

Abstract

We use oxygen vacancy formation energy (OVFE) as a measure of how easily lattice oxygen may participate in the Mars and Van Krevelen mechanism for oxidation reactions. We calculate with density functional theory how OVFE is affected when some of Zn atoms in ZnO(101̄0) surface layer are substituted by other metal dopants. We find that Li, Na, K, Rb, Cs, Os, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, and Cd decrease OVFE and prefer to be located at the surface of ZnO rather than in the bulk. Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf, Ce, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Al, Ga, Sn, and Pb increase OVFE. Most of the dopants that increase OVFE prefer to substitute Zn atoms in the bulk, except for Ca, Sr, Ba, La, Ce, Re, Fe, Ru, Co, Sn, and Pb, which prefer to substitute a Zn atom at the surface. These calculations lead us to conclude that doping an oxide is an efficient method of modifying its oxidative power.