Fig. 1: Schematic of electron withdrawing effect from Ce4+.
From: Adsorption and activation of molecular oxygen over atomic copper(I/II) site on ceria
From bulk CuO to atomic Cu(I/II) site, continuous band structure becomes discrete molecular orbitals. Evac, Ec, Ev, ELUMO and EHOMO represent for the energy level of vacuum, conductive band, valence band, LUMO and HOMO, respectively. The HOMO and LUMO gap increased in comparison between bulk and atomic Cu(I/II) site. This is indicated by the study of occupied 3d orbitals and unoccupied 4p orbitals energy levels, respectively. The schematic structures illustrate the atomic Cu(I/II) site concept and do not represent the real surface species.
