Boosting oxygen activation in ceria-oxide via gallium addition

Abstract

CeO2 is a well-suited support due to its higher oxygen storage capacity and reversible redox ability, which is associated with the oxygen activation. Herein we report the effective oxygen activation in CeO2 by gallium incorporation, varying the Ga/Ce molar ratios from 0.25 to 0.75. Structural results and operando spectroscopies under reaction conditions revealed that gallium incorporation improves the oxygen activation in CeO2, being more effective at low gallium content (Ga/Ce of 0.25). Atomic-scale computations demonstrated that the 0.25 Ga/Ce molar ratio generates Ga atomic-size channels that allow an easy way for oxygen diffusion from bulk to the surface. Ga incorporates into the subsurface Ce layer causing a collective effect: weakening the surface Ce-O bonds, boosting the surface oxygen activation, then enhancing the CO oxidation ability. Once this happens, it leaves behind O-vacancies, which may occupy either bulk oxygen from the CeO2 or further renovation of oxygen atoms from the environment.