Construction of MXene functionalized wood-based hydrogels using ZnCl2 aqueous solution for flexible electronics

Abstract

Hydrogels fabricated from top-down wood nanotechnology have attracted a lot of attention. Herein, two-dimensional and conductive MXenes are utilized as fillers and functional agents to impart a wood hydrogel with multifunctionality. Specifically, a wood substrate was directly converted into a wood hydrogel using an inorganic ZnCl₂ solution system. ZnCl₂ has a dual role in promoting the exfoliation and dispersion of MXenes, and simultaneously inducing the rearrangement of cellulose fibers. An extensive hydrogen bonding network between cellulose and MXenes can be constructed, and the ionic coordination between Zn²⁺ ions and hydroxyl groups serves as a secondary cross-linked network for the composite hydrogel. Enabled by the MXenes and Zn²⁺ ions, the as-prepared wood hydrogel presents well-preserved anisotropy, superior mechanical performance, high conductivity and extreme temperature tolerance. Moreover, the wood hydrogels demonstrate huge potential in the healthcare monitoring applications of human motion detection, temperature sensing and photothermal conversion. This study provides a simple strategy for developing wood hydrogel sensor systems with high conductivity and a wide temperature range response.