Electrocatalysis and redox behavior of Pt2+ ion in CeO2 and Ce0.85Ti0.15O2: XPS evidence of participation of lattice oxygen for high activity

Electronic states of CeO2, Ce1 -aEuro parts per thousand x Pt (x) O2 -aEuro parts per thousand delta , and Ce1 -aEuro parts per thousand x -aEuro parts per thousand y Ti (y) Pt (x) O2 -aEuro parts per thousand delta electrodes have been investigated by X-ray photoelectron spectroscopy as a function of applied potential for oxygen evolution and formic acid and methanol oxidation. Ionically dispersed platinum in Ce1 -aEuro parts per thousand x Pt (x) O2 -aEuro parts per thousand delta and Ce1 -aEuro parts per thousand x -aEuro parts per thousand y Ti (y) Pt (x) O2 -aEuro parts per thousand delta is active toward these reactions compared with CeO2 alone. Higher electrocatalytic activity of Pt2+ ions in CeO2 and Ce1 -aEuro parts per thousand x Ti (x) O-2 compared with the same amount of Pt-0 in Pt/C is attributed to Pt2+ ion interaction with CeO2 and Ce1 -aEuro parts per thousand x Ti (x) O-2 to activate the lattice oxygen of the support oxide. Utilization of this activated lattice oxygen has been demonstrated in terms of high oxygen evolution in acid medium with these catalysts. Further, ionic platinum in CeO2 and Ce1 -aEuro parts per thousand x Ti (x) O-2 does not suffer from CO poisoning effect unlike Pt-0 in Pt/C due to participation of activated lattice oxygen which oxidizes the intermediate CO to CO2. Hence, higher activity is observed toward formic acid and methanol oxidation compared with same amount of Pt metal in Pt/C.