Preparation and characterization of highly conductive lignin aerogel based on tunicate nanocellulose framework

In situ growth of MnO2 on graphitized cellulose nanocrystal: A novel coaxial heterostructures with unblocked conductive networks as advanced electrode materials for supercapacitor

Manganese dioxide (MnO2) with high theoretical capacitance and natural abundance has attracted great attention but is still challenging for use in supercapacitors, due to the limited conductivity and lower electron and ion migration. Here, a facile in situ growth strategy is developed to prepare heterostructural graphitized cellulose nanocrystal (GCNC)/MnO2 with unblocked conductive networks through a hydrothermal reaction. The GCNC with highly ordered graphitic carbon layers as conductive support framework solves the agglomeration problem of MnO2 and increases effective specific surface areas in contact with electrolyte ions. Meanwhile, the stable connection of MnOC covalent bonds enhances the interface bonding, which effectively reduces the contact resistance at the interface of heterostructural GCNC/MnO2 and enhances the interface firmness. The resulting GCNC/MnO2 electrode shows a remarkable specific capacitance of 528.2 F g-1 at 0.5 A g-1. Furthermore, the symmetric supercapacitor based on GCNC/MnO2-15 mM exhibits high rate capability and excellent cycle stability of 100 % capacitance retention after 3000 cycles. This work provides a new path to designing high performance electrode material for sustainable energy technologies.

High-performance electrode materials of heteroatom-doped lignin-based carbon materials for supercapacitor applications

Supercapacitors are the preferred option for supporting renewable energy sources owing to many benefits, including fast charging, long life, high energy and power density, and saving energy. While electrode materials with environmentally friendly preparation, high performance, and low cost are important research directions of supercapacitors. At present, the growing global population and the increasingly pressing issue of environmental pollution have drawn the focus of numerous researchers worldwide to the development and utilization of renewable biomass resources. Lignin, a renewable aromatic polymer, has reserves second only to cellulose in nature. Ten million tonnes of industrial lignin are produced in pulp and paper mills annually, most of which are disposed of as waste or burned for fuel, seriously depleting natural resources and polluting the environment. One practical strategy to accomplish sustainable development is to employ lignin resources to create high-value materials. Based on the high carbon content and rich functional groups of lignin, the lignin-based carbon materials generated after carbonization treatment display specific electrochemical properties as electrode materials. Nevertheless, low electrochemical activity of untreated lignin precludes it from achieving its full potential for application in energy storage. Heteroatom doping is a common modification method that aims to improve the electrochemical performance of the electrode materials by optimizing the structure of the lignin, improving its pore structure and increasing the number of active sites on its surface. This paper aims to establish theoretical foundations for design, preparation, and optimizing the performance of heteroatom-doped lignin-based carbon materials, as well as for developing high-value-added lignin materials. The most reported the mechanism of supercapacitors, the doping process involving various types of heteroatoms, and the analysis of how heteroatoms affect the performance of lignin-based carbon materials are also detailed in this review.

Preparation and characterization of a novel high barrier mulching film with tunicate cellulose nanocrystals/sodium alginate/alkali lignin

In this study, the base film (CSL) was prepared by blending tunicate cellulose nanocrystals (TCNCs) extracted from tunicate shells, with sodium alginate (SA) and alkali lignin (AL). Then, the mulching film (CSL-WK) was prepared using water-borne polyurethane (WPU) as binder to install low-energy Kaolin on the surface of CSL film. The influences of composition with different concentrations on mechanical properties were studied. The tensile strength and elongation at break of CSL-WK film could reach 86.58 MPa and 50.49 %, respectively. The mulching films were characterized by degradability test, SEM, FTIR, and TGA. TCNCs had good compatibility with SA and AL, and a rough structure was formed on the surface of the film to improve the hydrophobicity. The barrier properties, including ultraviolet resistance, water contact angle, water vapor permeability, water retention, and flame retardancy, were tested. The results showed that CSL-WK films could block 97 % of ultraviolet light, reduce about 25 % of soil water loss, and self-extinguish within 7 s of open flame ignition. Note that the secondary spraying method significantly improved the barrier property of films. This study lays a foundation for the preparation of ecologically friendly, biodegradable, and high barrier mulching film, and expands the application of marine resources.