Fabrication of three-dimensional microtubular kapok fiber carbon aerogel/RuO2 composites for supercapacitors

An ultra-thin and highly efficient electromagnetic interference shielding composite paper with hydrophobic and antibacterial properties

Facing the increasing electromagnetic interference (EMI) pollution in the living environment, it is a new trend to explore an efficient EMI shielding material with facile fabrication and a wide range of application scenarios. A hydrophobic composite paper composed of silver nanowires (AgNWs) and kapok microfibers cellulose (MFC) was modified by methyl trimethoxy silane (MTMS) through a simple method. As a result, the composite paper has a good EMI shielding effectiveness (EMI SE) of 61.7 dB with electrical conductivity of 695.41 S/cm. The modification of MTMS improved the thermal stability performance of composite paper, which also increased its water contact angle to 113°. The free silver ions (Ag+) released from AgNWs can kill surrounding microbial bacteria, endowing the composite paper with good antibacterial property. Water resistance and antibacterial property enable MTMS/AgNWs/MFC composite paper to cope with complex application environments.

Natural Hollow Fiber-Derived Carbon Microtube with Broadband Microwave Attenuation Capacity

Constructing hierarchical structures is indispensable to tuning the electromagnetic properties of carbon-based materials. Here, carbon microtubes with nanometer wall thickness and micrometer diameter were fabricated by a feasible approach with economical and sustainable kapok fiber. The carbonized kapok fiber (CKF) exhibits microscale pores from the inherent porous templates as well as pyrolysis-induced nanopores inside the wall, affording the hierarchical carbon microtube with excellent microwave absorbing performance over broad frequency. Particularly, CKF-650 exhibits an optimized reflection loss (RL) of −62.46 dB (10.32 GHz, 2.2 mm), while CKF-600 demonstrates an effective absorption bandwidth (RL < −10 dB) of 6.80 GHz (11.20−18.00 GHz, 2.8 mm). Moreover, more than 90% of the incident electromagnetic wave ranging from 2.88 GHz to 18.00 GHz can be dissipated by simply controlling the carbonization temperature of KF and/or the thickness of the carbon-microtube-based absorber. These encouraging findings provide a facile alternative route to fabricate microwave absorbers with broadband attenuation capacity by utilizing sustainable biomass.

Highly dispersed RuO2-biomass carbon composite made by immobilization of ruthenium and dissolution of coconut meat with octyl ammonium salicylate ionic liquid for high performance flexible supercapacitor

Poor dispersion of metal oxide-biomass carbon composite limits its further improvement in electrochemical properties. The study reports synthesis of highly dispersed RuO₂-biomass carbon nanocomposite (HD-RuO₂-BC). Octyl ammonium salicylate ionic liquid was combined with Ru³⁺ ion to form Ru-based ionic liquid. Followed by addition of coconut meat, microwave treatment to form homogeneous solution, thermal reduction in N₂ and oxidation in air in sequence. The resulting HD-RuO₂-BC shows three-dimensional architecture and high Ru loading of 9.2%. RuO₂ nanoparticles of 6.2 nm were uniformly dispersed in biomass carbon sheets. Excellent dispersion and small size of RuO₂ nanoparticles achieve to a significant synergy between RuO₂ and biomass carbon. HD-RuO₂-BC electrode gives high capacitance of 907.7 F g^-1 at 1 A g^-1. The value is more than that of BC (150.6 F g^-1) and RuO₂ electrodes (584.7 F g^-1), verifying that introduction of RuO₂ achieves to an obviously enhanced capacitance. The symmetrical flexible supercapacitor exhibits excellent supercapacitor performances, including high capacitance (403.8 F g^-1 at 1.0 A g^-1), rate-capacity (223.1 F g^-1 at 50 A g^-1), cycling stability (98.2% capacity retention after 10,000 cycles at 50 A g^-1) and energy density (378.7 Wh Kg^-1at power density of 5199.2 W kg^-1).

Wood-Derived Carbon Materials and Light-Emitting Materials

Wood is a sustainable and renewable material that naturally has a hierarchical structure. Cellulose, hemicellulose, and lignin are the three main components of wood. The unique physical and chemical properties of wood and its derivatives endow them with great potential as resources to fabricate advanced materials for use in bioengineering, flexible electronics, and clean energy. Nevertheless, comprehensive information on wood-derived carbon and light-emitting materials is scarce, although much excellent progress has been made in this area. Here, the unique characteristics of wood-derived carbon and light-emitting materials are summarized, with regard to the fabrication principles, properties, applications, challenges, and future prospects of wood-derived carbon and light-emitting materials, with the aim of deepening the understanding and inspiring new ideas in the area of advanced wood-based materials.

Compressible, anisotropic lamellar cellulose-based carbon aerogels enhanced by carbon dots for superior energy storage and water deionization

Heteroatom-doped carbon materials have received great attention for applications in electrode materials. However, conventional heteroatom-doping methods sacrifice conductivity, stability, and specific surface area (SSA). Here, the carbon quantum dots (CDs) are used as carriers of N, P, O to form electron-rich regions promoting electron transport without decreasing stability and SSA. The CDs promote the formation of graphitic nitrogen in the composite, which effectively reduces their internal resistance by increasing the dielectric constant. Moreover, the orderly growth of ice crystals generates a unique bridged layer structure under bidirectional freeze-casting in a mixture of GO/CDs/microfibrillated cellulose, which gives the composite super-compressibility. Notably, the optimal sample has a 117% increase in specific capacitance. The CDs also improve wettability and thus reduce the charge transfer resistance giving a large desalination capacity of 32.59 mg g^-1 (504 mg L^-1 NaCl). This work illustrates the unique role of CDs in improving the electrochemical performance of composites.