Liquefaction of Cellulose for Production of Advanced Porous Carbon Materials

Cellulose is a renewable resource for the production of advanced carbonaceous materials for various applications. In addition to direct carbonization, attention has recently been paid to the preparation of porous carbons from liquid cellulose-based precursors. Possible pathways of cellulose conversion to a liquid state suitable for the preparation of porous carbons are summarized in this review. Hydrothermal liquefaction leading to liquid mixtures of low-molecular-weight organics is described in detail together with less common decomposition techniques (microwave or ultrasound assisted liquefaction, decomposition in a strong gravitation field). We also focus on dissolution of cellulose without decomposition, with special attention paid to dissolution of nonderivatized cellulose. For this purpose, cold alkalines, hot acids, ionic liquids, or alcohols are commonly used.

Jackfruit Seed-Derived Nanoporous Carbons as the Electrode Material for Supercapacitors

Hierarchically porous activated carbon materials from agro-waste, Jackfruit seeds are prepared by a chemical activation method involving the treatment with zinc chloride (ZnCl2) at different temperatures (600–1000 °C). The electrochemical supercapacitance performances of the prepared materials were studied in an aqueous electrolyte (1 M sulfuric acid, H2SO4) in a three-electrode system. Jackfruit seed carbons display nanoporous structures consisting of both micro- and mesopore architectures and they are amorphous in nature and also contain oxygenated surface functional groups, as confirmed by powder X-ray diffraction (pXRD), Raman scattering, and Fourier-transformed infrared (FTIR) spectroscopy, respectively. The surface areas and pore volumes were found to be 1216.0 to 1340.4 m2·g−1 and 0.804 to 1.144 cm3·g−1, respectively, demonstrating the better surface textural properties compared to the commercial activated carbons. Due to the high surface area, large pore volume, and well developed hierarchical micro- and mesoporosity, the optimal sample achieved a high specific capacitance of 292.2 F·g−1 at 5 mV·s−1 and 261.3 F·g−1 at 1 A·g−1 followed by outstanding high rate capability. The electrode sustained 71.6% capacity retention at a high current density of 20 A·g−1. Furthermore, the electrode displayed exceptional cycling stability with small capacitance loss (0.6%) even after 10,000 charging–discharging cycles, suggesting that Jackfruit seed would have potential in low-cost and scalable production of nanoporous carbon materials for supercapacitors applications.

MoS2 /MoOx -Nanostructure-Decorated Activated Carbon Cloth for Enhanced Supercapacitor Performance

MoS₂ /MoO_x nanostructures were grown on activated carbon cloth through a facile one-step microwave-assisted hydrothermal method. The growth of MoS₂ /MoO_x on activated carbon cloth creates a unique structure that favors ion intercalation. The conductive activated carbon cloth, MoO_3-x , and monoclinic MoO₂ provide fast electron transport, whereas the MoS₂ nanosheets/MoO_3-x nanoparticles structure improves the capacitance. As a result, MoS₂ /MoO_x -nanostructure-decorated activated carbon cloth shows a high specific capacitance of 230 F g^-1 at a scan rate of 5 mV s^-1 with a low contact resistance of approximately 1.91 Ω. Moreover, the activated carbon cloth acts as a template for the growth of a perpendicular MoS₂ layer, which gives an excellent utilization rate of the active MoS₂ /MoO_x material. We also demonstrate that the MoS₂ /MoO_x /activated carbon cloth nanocomposite shows excellent electrochemical stability with retention up to 128 % after 1500 cycles. Finally, we show the use of a microwave-assisted hydrothermal method for the synthesis of the MoS₂ /MoO_x /activated carbon cloth nanocomposite as an alternative and clean route to improve the kinetics of the intercalation redox reaction.