Bamboo-derived carbon nanospheres/polyvinyl alcohol composite coatings for sustainable dual-functional protection of paper-based cultural relics against UV radiation and acidification-induced degradation.

Paper-based cultural relics face degradation from ultraviolet radiation and oxidative free radicals, causing cellulose chain breakage, yellowing, acidification, and mechanical property decline. This study develops a green protection strategy using bamboo-derived carbon nanospheres (B-CNSs), prepared via one-step carbonization in deep eutectic solvent, combined with polyvinyl alcohol (PVA) as a composite coating. Transmission electron microscopy reveals spherical B-CNSs with ∼150 nm diameter. X-ray diffraction confirms transformation from crystalline cellulose to amorphous carbon. XPS shows surface O (31.90%) and N (4.41%) with C-O (33.76%) and O=C-OH (18.98%) functional groups. DPPH assay gives IC50of 2.9μg ml-1. The coating effectively inhibits glycosidic bond cleavage and carbonyl formation, preserves fiber hydrogen bonding, and suppresses UV-induced pH decline. Treated papers show significantly enhanced tensile strength, reduced yellowing, and superior UV shielding after accelerated aging. This work offers a sustainable pathway for bamboo valorization and dual-functional conservation of paper-based cultural relics.