A multifunctional hydrogel of cellulose nanofiber/microfibrillated cellulose hierarchical network for photothermal antibacterial and all-solid supercapacitor assembly

In recent years, flexible-hydrogel wearable devices have undergone rapid development while photothermal therapy, energy storage/conversion, and other fields have been widely developed and used. However, the poor mechanical properties of hydrogels can affect their stability and reliability in practical applications, and it is often difficult to achieve both excellent mechanical properties and multifunctional characteristics. This study prepared a hierarchical cellulose network/PVA multifunctional composite hydrogel (MCPH) using cellulose nanofiber as fine fibers and microfibrillated cellulose as coarse fibers. The hierarchical cellulose network provides tensile strength as a skeleton while the PVA serves as the soft matrix to assist energy dissipation, which provides the composite hydrogel with good mechanical properties (toughness of 1.21 MJ m −3 and tensile modulus of 2.20 MPa). In addition, owing to hierarchical cellulose network preventing excessive stacking of MXene while achieving stable series connection of nano fillers, MCPH exhibits excellent photothermal conversion rate, photothermal antibacterial ability (viability of Escherichia coli and Staphylococcus aureus  < 0.88 %), and energy storage capacity (6886 mF/cm 2 ). Thus, this study not only prepared a composite hydrogel with good mechanical properties and excellent multifunctional properties but also expanded the application potential of cellulose, an important green renewable plant resource, in high-value-added wearable products.