Integration of Carbon Quantum Dots and Lignin Into Transparent Nanocellulose Films for Efficiently Blocking UV and High‐Energy Blue‐Violet Light

ABSTRACT Overexposure to ultraviolet (UV) and high‐energy blue‐violet light (HEBV) can cause severe skin and eye damage. In this study, lignin‐containing cellulose nanofibrils (LCNF) films are prepared from cellulose pulps with varying lignin contents obtained through hydrogen peroxide‐acetic acid pretreatment of bagasse. The LCNF films possess excellent hydrophobicity and mechanical properties, as well as certain UV radiation resistance properties, by leveraging the inherent properties of lignin. To enhance the UV shielding performance of LCNF films, blue‐ and green‐emitting carbon dots (BL‐CQDs, GL‐CQDs) derived from lignin are prepared and incorporated as UV absorbers alongside LCNF to construct sustainable, biodegradable composite films with high‐efficiency UV shielding properties, in which lignin‐based carbon quantum dot (L‐CQDs) are uniformly embedded within the LCNF network via hydrogen bonding. Through the synergistic interaction between lignin and L‐CQDs, the UV blocking rate of L‐CQDs@LCNF films increased by 8.15%–36.40%, and the HEBV blocking rate increased by 2.95%–41.52% while maintaining excellent visible light transmittance and mechanical properties (with tensile strength reaching up to 82 MPa), compared to pure LCNF films. Simultaneously, by regulating the lignin content in LCNF and the properties of L‐CQDs, the films exhibit tunable UV blocking and blue‐violet light shielding capabilities. Additionally, the prepared BL‐CQDs achieve a fluorescence quantum yield of 31.10%, representing a leading level among lignin‐derived CQDs. This study will provide a strategy for preparing transparent and full‐lignocellulose films with tunable UV‐blocking and blue‐violet light shielding properties through a design integrating function and structure.