Cerium oxide catalyzed disproportionation of hydrogen peroxide: a closer look at the reaction intermediate

TL;DR

This study investigates the fundamental mechanism of cerium oxide nanoparticles catalyzing hydrogen peroxide disproportionation, revealing stable cerium-peroxo intermediates and linking catalytic activity to Ce(III) content, with implications for biomedical antioxidant applications.

Contribution

It provides new insights into the reaction mechanism by identifying cerium-peroxo complexes and correlates catalytic activity with Ce(III) fraction, advancing understanding of CNPs as enzyme mimetics.

Findings

H2O2 adsorption forms cerium-peroxo complexes detectable by Raman and UV-Vis spectroscopy.

Catalytic reactivity increases with higher Ce(III) fraction in CNPs.

UV-Vis spectroscopy can characterize catalytic intermediates and predict reactivity.

Abstract

Cerium oxide nanoparticles (CNPs) have recently gained increasing interest as redox enzyme-mimetics to scavenge the intracellular excess of reactive oxygen species, including hydrogen peroxide (H2O2). Despite the extensive exploration of CNP scavenging activity, there remains a notable knowledge gap regarding the fundamental mechanism underlying the CNP catalyzed disproportionation of H2O2. In this Letter, we present evidence demonstrating that H2O2 adsorption at CNP surface triggers the formation of stable intermediates known as ceriumperoxo complexes (Ce-O2 2-). The cerium-peroxo complexes can be resolved by Raman scattering and UV-Visible spectroscopy. We further demonstrate that the catalytic reactivity of CNPs in the H2O2 disproportionation reaction increases with the Ce(III) fraction. The developed approach using UV-Visible spectroscopy for the characterization of Ce-O2 2-complexes can potentially serve as a foundation for determining the catalytic reactivity of CNPs in the disproportionation of H2O2.