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In this study, porous carbon nanofibers were produced via one-step carbonization and activation of cellulose acetate/polyacrylonitrile (CA/PAN) hybrid nanofibers using electrospinning. Zinc acetate effectively enhanced the thermal stability of CA without deacetylation and served as a template for pore creation. The effect of the mass ratio of CA to PAN on the microstructure and capacitive properties of the resulting carbon nanofiber membrane electrodes was investigated. All the membrane electrodes displayed self-supporting structures. The specific surface area, pore volume and specific capacitance of the membrane electrodes gradually increased with an increase in the CA : PAN mass ratio from 2 : 1 to 6 : 1, and then slightly decreased when the mass ratio reached 8 : 1. The CNF-C6P1 membrane electrode exhibited excellent flexibility, with a maximum specific surface area of ∼563.8 m2 g−1, largest specific capacitance of 132.2 F g−1 at 0.5 A g−1, and excellent rate capability of 53.3% at 20 A g−1. After 4000 cycles of the charge/discharge process in a two-electrode system, this membrane electrode could still retain 85.1% of the original specific capacitance and the coulombic efficiency was close to 100%, showing high electrochemical stability and reversibility. This work provides a simple and effective strategy for the design and synthesis of flexible electrode materials for supercapacitors from cellulose acetate. [ABSTRACT FROM AUTHOR]

A reusable magnetic WC-Co composite (Co/C-1000) filter with efficient water treatment was prepared by in-situ growth of ZIF-67 on the inside and outside surface of wood following by carbonization. [Display omitted] • Magnetic WC-Co composite is designed for wastewater treatment. • WC-Co composite has ultra-high dyes adsorption capacity. • The Co/C-1000 filter has good removal efficiency for high dye concentration solution at a higher flux. • The Co/C-1000 filter with excellent thermal stability can be recycled by simple burning method. Organic dye in water is a crucial global environmental problem. Notably, dyes, especially anionic dye Congo red (CR) and cationic dye Methylene blue (MB), have carcinogenic and mutagenic effects on human health. However, the commercial activated carbon with bad reusability is difficult to collect, which results in poor actual adsorption. In this paper, ZIF-67@wood obtained by in situ growth of ZIF-67 on wood is carbonized to prepare magnetic WC-Co composites. The hierarchical porous structure of wood can facilitate the rapid passage of dye solution, and promote full contact between magnetic core–shell Co/C nanoparticles and dyes. The adsorption capacities of CR and MB by Co/C-1000 are 1117.03 and 805.08 mg g−1, respectively. The pH pzc (7.9) of Co/C-1000 is then determined. When the dye concentration reaches 1200 mg L−1, the removal efficiency of Co/C-1000 reaches 99.98% under gravity. With the flux of 1.0 × 104 L m−2h−1 for CR solution (100 mg L−1), the removal efficiency of Co/C-1000 filter connected with peristaltic pump is almost 99.28%. In addition, the Co/C-1000 filter with high reusability and the adsorbed dyes can be removed by simple burning. This economical, recyclable and self-supporting filter with ultra-high adsorption capacity feature has the potential to replace commercial activated carbon and it will be widely used in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

The capacitive performances of carbon materials greatly rely on the porous structure and conductive network. However, the compromise of carbon materials with suitable porosity and 3D conductive framework still exists difficulty. Herein, a hierarchical porous free-standing carbon nanofiber (CNF) membrane was obtained from electrospun cellulose acetate (CA) nanofiber membrane via one-step carbonization and activation process. The influence of carbonization temperature on microstructure and electrochemical performance of carbons are investigated. The 800 °C carbonized sample CA-CNFs-800 exhibits large specific surface area of 720.8 m2 g−1 and suitable pore size distribution. The micropore dominated structure and three-dimensional conductive carbon networks enable fast electron/ion transport. The specific capacitance reaches 229.4 F g−1 at 0.2 A g−1 with good rate performance of 72.8% capacitance retention at 20 A g−1 for CA-CNFs-800. Moreover, CA-CNFs-800 possess high capacitance retention of 97.3% after 40,000 cycles at 20 A g−1. The CA-CNFs outperform other bio-based carbon materials, highlighting the great promise of CA-based CNFs for improving the capacitive performance of supercapacitors in electronic energy storage devices. [Display omitted] • The free-standing carbon nanofiber membranes are fabricated via electrospinning, and following one step carbonization/activation process. • The cellulose acetate derived carbon nanofiber membranes display hierarchical porous structure with high specific surface area. • The as-prepared electrode materials with 3D conductive network exhibit high specific capacitance and good cycling stability. • The a single supercapacitor assembled in series is able to easily light red light-emitting diodes and hold for 50 s. [ABSTRACT FROM AUTHOR]