Toward efficient broad-spectrum UV absorption of carbon dots: Facile preparation, performance characterization and its application as UV absorbers

UV absorbers are sustainable substances that inhibit the ultraviolet (UV) radiative degradation of polymers. In previous reports, the as-prepared carbon dots (CDs) possess only an absorption band at UVA (320–400 nm). To achieve broad-spectrum UV absorption (200–400 nm), increasing the concentration of the CDs solution becomes common. However, a high concentration solution seriously affects the light transmittance due to its heavy yellow color. Furthermore, the promising organic UV absorbers cannot achieve broad-spectrum UV absorption. In this work, we initially synthesized three-component water-soluble carbon dots (OP–CDs), which delivers an excellent UV absorption (98 % UVA and 100 % UVB at the concentration of 1.7 × 10−2 mg/mL; 99 % transmittance in visible light). Moreover, OP–CDs exhibit outstanding stability at high temperatures and different pH. With the corporation of OP–CDs and polyvinyl alcohol (PVA), a high-performance UV-shielding film was formed, leading to enhanced broad-spectrum UV shielding performance and improved mechanical properties, resistance of photocatalytic activity and anti-UV aging ability compared with pure PVA film. Notably, the PVA film remains high transparency with the addition of OP–CDs. The study suggests that the corporation of OP–CDs and polymers is effective in anti-UV degradation.