Engineering Ultra-small CeO2 NPs with Antioxidant and UV-shielding Properties as Functional Nanomaterials in Composite Coatings for Complex Surface Protection

The development of advanced catalytic shields against UV-induced and oxidative degradation is critical to address multifaceted deterioration processes. The maximization of the surface-to-volume ratio in ultra-small cerium oxide nanoparticles (CeO2 NPs) favors the Ce(III)/Ce(IV) exchange on the surface and the formation of oxygen vacancies, creating the ideal platform to target entangled degradation. Here, we designed a microwave-assisted process to obtain highly stable CeO2 NPs (2 nm), and we demonstrated their redox cycling by means of Environmental XPS. Thereafter, we developed a polymer nanocomposite formulation in which the biopolymer and the nanomaterial work synergistically to provide a protective action without hindering the active sites at the surface of the NPs. We tested the protective action in the challenging context of frescoes conservation. Their surfaces are often subjected to pigment degradation, triggered by light, salts, and high relative humidity. We verified how the CeO2 NPs-based coating effectively mitigates complex deterioration mechanisms.