Abstract
Atomic nitrogen doping on CeO(2) nanoparticles (NPs) by an efficient and environmentally benign urea thermolysis approach is first studied, and its effects on the intrinsic scavenging activity of the CeO(2) NPs for reactive oxygen radicals are investigated. The N-doped CeO(2) (N-CeO(2)) NPs, characterized by X-ray photoelectron and Raman spectroscopy analyses, showed considerably high levels of N atomic doping (2.3-11.6%), accompanying with an order of magnitude increase of the lattice oxygen vacancies on the CeO(2) crystal surface. The radical scavenging properties of the N-CeO(2) NPs are characterized by applying Fenton's reaction with collective and quantitative kinetic analysis. The results revealed that the significant increase of surface oxygen vacancies is the leading cause for the enhancements of radical scavenging properties by the N doping of CeO(2) NPs. Enriched with abundant surface oxygen vacancies, the N-CeO(2) NPs prepared by urea thermolysis provided about 1.4-2.5 times greater radical scavenging properties than the pristine CeO(2). The collective kinetic analysis revealed that the surface-area-normalized intrinsic radical scavenging activity of the N-CeO(2) NPs is about 6- to 8-fold greater than that of the pristine CeO(2) NPs. The results suggest the high effectiveness of the N doping of CeO(2) by the environmentally benign urea thermolysis approach to enhance the radical scavenging activity of CeO(2) NPs for extensive applications such as that in polymer electrolyte membrane fuel cells.