Wavelength‐Selective Photoreduction of Colloidal CeO2–x Nanocrystals

• Published in: physica status solidi (b) 2019-12, Vol.256 (12), p.n/a
• Main Authors: Seminko, Vladyslav, Maksimchuk, Pavel, Avrunin, Oleg, Semenets, Valerii, Malyukin, Yuri
• Format: Article
• Language: English
• Subjects: antioxidants; ceria; hydrogen peroxide; luminescence; photoreduction
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201900325

The Ce3+ ↔ Ce4+ redox dynamics of colloidal nanoceria at hydrogen peroxide (HP) addition is studied using the luminescence of Ce3+ cations. The fast oxidation (Ce3+ → Ce4+) and slow reduction (Ce4+ → Ce3+) phases of nanoceria–oxidant interaction are discussed. Both the phases are mediated by oxygen diffusion within ceria nanoparticles. Laser‐light irradiation with specific wavelengths causes a significant acceleration of Ce4+ → Ce3+ reduction phase. This effect is observed only under excitation to the charge‐transfer (Ce4+–O2−) absorption band of nanoceria. The partial transfer of charge from oxygen to cerium ions leads to decrease in the binding energy and the effective radius of O2− anions accelerating the oxygen diffusion in the nanoceria lattice. Nanoceria is widely studied as unique self‐regenerative scavenger of reactive oxygen species. However, the recovery of antioxidant properties of nanoceria after nanoceria–oxidant interaction is hampered by low oxygen mobility in ceria nanoparticle at room temperature. The oxygen release can be promoted using continuous laser irradiation with wavelengths corresponding to Ce4+–O2− absorption.