Enhanced Dielectric Properties of All-Cellulose Composite Film via Modulating Hydroxymethyl Conformation and Hydrogen Bonding Network.

Cellulose-based dielectrics with attractive dielectric performance are promising candidates to develop eco-friendly electrostatic energy storage devices. Herein, all-cellulose composite films with superior dielectric constant were fabricated by manipulating the dissolution temperature of native cellulose, where we revealed the relationship among the hierarchical microstructure of the crystalline structure, the hydrogen bonding network, the relaxation behavior at a molecular level, and the dielectric performance of the cellulose film. The coexistence of cellulose I and cellulose II led to a weakened hydrogen bonding network and unstable C6 conformations. The increased mobility of cellulose chains in the cellulose I-amorphous interphase enhanced the dielectric relaxation strength of side groups and localized main chains. As a result, the as-prepared all-cellulose composite films exhibited a fascinating dielectric constant of as high as 13.9 at 1000 Hz. This work proposed here provides a significant step toward fundamentally understanding the dielectric relaxation of cellulose, thus developing high-performance and eco-friendly cellulose-based film capacitors.

In-situ structuring a robust cellulose hydrogel with ZnO/SiO2 heterojunctions for efficient photocatalytic degradation.

Hydrogel supported photocatalyst, an efficient strategy for water remediation suffers from compromised catalytic activity and insufficient stability. Herein, a robust cellulose-based composite hydrogel with zinc oxide (ZnO)/silica (SiO2) heterojunctions were fabricated by in-situ synthesis, where SiO2 not only acted as a cross-linking agent to enhance the mechanical strength and stability of hydrogel, but also promoted the photocatalytic properties of ZnO via transferring the electron-hole pairs due to its surface state. As a result, a significant improvement in the mechanical properties of cellulose-based composite hydrogel was achieved, exhibiting a high compressive strength of 703.4 kPa. Moreover, the degradation efficiency of methylene blue (MB) under light irradiation by cellulose-based composite hydrogel was 95 % in 120 min and the removal ratio maintained as high as 90 % after eight degradation cycles. This study provides a low-cost and facile method to construct new hydrogel supports with high stability and efficient photocatalytic properties.