Hemicellulose phase synergistically boosting the tribopositivity of cellulose nanopaper: Effectiveness and mechanism

The integration of lignocellulosic nanomaterials into energy management applications possesses enormous technical appeals catering to high-tech and low-carbon era. Nature has designed hierarchical and heterogeneous lignocellulose microstructure, which can be harnessed for desirable dielectric behaviors towards specific applications. Here, we make the first attempt to boost the tribopositivity of 2D self-assembly (i.e., nanopaper) of cellulose nanofibrils by leveraging the inherent functionality of their hemicellulose phase. In comparison to conventional nanopapers assembled from TEMPO-oxidized/enzymatic cellulose nanofibrils with significantly lower hemicellulose content (4.6/12.2 vs. 20.3 wt%), the as-prepared hemicellulose-rich nanopaper exhibits ~2-fold higher electron-donating capability, which in turn generates ~1.5-fold higher triboelectric nanogenerator (TENG) output when paired with given tribonegative materials. We provide multiscale insights into the boosted tribopositivity of nanopaper by hemicellulose phase arising from its unique molecular structure and micro-distribution pattern. Furthermore, amorphous hemicellulose phase can be readily molecularly designed, e.g., aminosilanization, which further enhances the tribopositivity of nanopaper towards self-powered applications requiring high energy density. Besides, the hemicellulose-rich nanopaper is highly writable, mechanically strong, and optically transparent, serving as a desired structural material with favorable programmability for various TENG-based sensing, encryption and wearable devices.