Transparent cellulose-lignin films containing Fe with high UV absorption for thermal management.

In this paper, cellulose-lignin films containing Fe were prepared by the codissolution-precipitation method, and the films have high transparency as well as high UV absorption. In this process, kraft lignin chelates with Fe and then bonds with cellulose through hydrogen bonding, evenly distributing within the film. The morphological results showed that the kraft lignin chelated with Fe bound tightly linked to cellulose within the Fe@cellulose-lignin composite films. The addition of Fe made the composite film (C-Fe-L) maintain a high transmittance of 66.9 % at 600 nm with excellent UV absorption. Excellent UV absorption performance, completely shielded from both Ultraviolet A (UVA), Ultraviolet B (UVB), and Ultraviolet C (UVC), and improved the thermal stability of the film. Under 100 mW cm solar irradiation, the temperature of C-Fe-L rose rapidly to 60.7 °C. Based on this property, solar energy is transformed into kinetic energy, which realizes the photothermal conversion of solar energy. This work realizes the use of transparent films for energy utilization.