Cerium oxide nanoparticles (‘nanoceria’) have gained attention as a promising photocatalyst for wastewater treatment and photochemical water splitting. In cerium oxide, Ce4+ in the lattice can be readily reduced to Ce3+, and the change in charge can be compensated by oxygen vacancy formation. Oxygen vacancies are often discussed as benefitting photocatalysis, but controlling oxygen vacancies in nanoceria may be difficult, especially at room temperature. For example, photoirradiation of fully oxidized nanoceria is thought to create Ce3+ centers, which are stabilized near the nanoparticle surface, without oxygen vacancy generation. Control over oxygen vacancies in nanoceria is needed to understand how they affect photochemical events in room-temperature dispersions. Here, we use aliovalent doping of nanoceria with La3+ to control oxygen vacancy levels. La3+-doped nanoceria and pure nanoceria samples were characterized by X-ray diffraction and X-ray fluorescence spectroscopy. Raman spectroscopy confirmed that oxygen vacancies are present in La3+-doped nanoceria. UV irradiation of the La3+-doped cerium oxide nanoparticles causes a persistent decrease in their UV absorption, demonstrating the accumulation of stable Ce3+ centers through photoreduction. These results pave the way for detailed photochemical studies of how tunable concentrations of Ce3+ centers and oxygen vacancies affect the photocatalytic efficiency of nanoceria.

Controlling oxygen vacancy levels in nanoceria for photochemical studies through aliovalent doping

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.