Manipulation of CO adsorption over Me/CeO by heterocation doping: Key roles of single-atom adsorption energy.

The performance of metal atoms chemically bonded to oxide supports cannot be explained solely by the intrinsic properties of the metals such as the d-band center. Herein, we present an in-depth study of the correlation between metal-oxide interactions and the properties of the supported metal using CO adsorption on Me (Fe, Co, and Ni) loaded over CeO (111) doped with divalent (Ca, Sr, and Ba), trivalent (Al, Ga, Sc, Y, and La), and quadrivalent (Hf and Zr) heterocations. CO adsorption over Me is strongly dependent on the binding energies of Me. Two factors led to this trend. First, the extent of the Me-surface oxygen (Me-O) bond relaxation during CO adsorption played a key role. Second, the d-band center shifted drastically because of charge transfer to the oxides. The shift is related to the oxophilicity of metals. Adsorption energies of Me over oxides include the contributions of the factors described above. Therefore, we can predict the activities of Me using the strength of anchoring by oxide supports. Results show that smaller ionic radii of the doped heterocations were associated with more tightly bound Me. This finding sheds light on the possibility of heterocation-doping manipulating the reactivity of the Me catalyst based on theoretical predictions.