Preparation of Network-Structured Carbon Nanofiber Mats Based on PAN Blends Using Electrospinning and Hot-Pressing Methods for Supercapacitor Applications

Rice straw -derived lignin-based carbon nanofibers as self-supporting electrodes for supercapacitors and lithium-ion batteries

Self-supporting carbon fibers are extensively employed as active components in energy storage systems due to their tunable microstructures, large specific surface area, affordability, and excellent electrical conductivity. Nevertheless, conventional methods for producing carbon fibers typically involve complicated synthesis processes, environmental pollution, and high energy consumption. In this study, lignin-based carbon nanofibers (LCNFs) were prepared through electrospinning and subsequent heat treatment. The morphologies, crystal structures, and specific surface area of the as-prepared LCNFs were characterized using scanning electron microscopy, X-ray diffraction and nitrogen sorption isotherms. The influence of lignin content on the on the structural, morphological, and electrochemical properties of the carbon nanofibers were examined, particularly in their applications as supercapacitor and lithium-ion battery anode materials. The as-prepared LCNF-2 possess the highest specific surface area of 468.3 m2 g-1. As a self-supporting electrode in supercapacitors (SCs), the LCNF-2 delivered 256.3 F g-1 at 0.2 A g-1, and capacitance retention of 62.0 % at the current density raised from 0.5 to 10 A g-1. The assembled LCNF-2//LCNF-2 symmetric supercapacitor demonstrated a specific capacitance of 168 F g-1 at 5 A g-1, maintaining 100 % capacitance retention after 10,000 cycles. Additionally, it achieved an energy density of 5.6 Wh kg-1 at a power density of 1250.0 W kg-1. As a lithium-ion batteries (LIBs) anode, the LCNF-2 showed a discharge specific capacity of 1108.3 mAh g-1 and a discharge specific capacity of 377.3 mAh g-1 in the first cycle, with a capacity retention rate of 84.6 % after 100 cycles at 1C. This work offers a novel approach for the high-value utilization of agricultural waste straw lignin in energy storage devices.

Promotion of adipose stem cell transplantation using GelMA hydrogel reinforced by PLCL/ADM short nanofibers

Adipose-derived mesenchymal stem cells (ADSCs) show poor survival after transplantation, limiting their clinical application. In this study, a series of poly(l-lactide-co-ϵ-caprolactone) (PLCL)/acellular dermal matrix (ADM) nanofiber scaffolds with different proportions were prepared by electrospinning. By studying their morphology, hydrophilicity, tensile mechanics, and biocompatibility, PLCL/ADM nanofiber scaffolds with the best composition ratio (PLCL:ADM = 7:3) were selected to prepare short nanofibers. And based on this, injectable gelatin methacryloyl (GelMA) hydrogel loaded with PLCL/ADM short nanofibers (GelMA-Fibers) was constructed as a transplantation vector of ADSCs. ADSCs and GelMA-Fibers were co-cultured, and the optimal loading concentration of PLCL/ADM nanofibers was investigated by cell proliferation assay, live/dead cell staining, and cytoskeleton stainingin vitro. In vivoinvestigations were also performed by H&E staining, Oil red O staining, and TUNEL staining, and the survival and apoptosis rates of ADSCs transplantedin vivowere analyzed. It was demonstrated that GelMA-Fibers could effectively promote the proliferation of ADSCsin vitro. Most importantly, GelMA-Fibers increased the survival rate of ADSCs transplantation and decreased their apoptosis rate within 14 d. In conclusion, the constructed GelMA-Fibers would provide new ideas and options for stem cell tissue engineering and stem cell-based clinical therapies.

A Facile Fabrication of Ordered Mesoporous Carbons Derived from Phenolic Resin and Mesophase Pitch via a Self-Assembly Method

Ordered and disordered mesoporous structures were synthesized by a self-assembly method using a mixture of phenolic resin and petroleum-based mesophase pitch as the starting materials, amphiphilic triblock copolymer F127 as a soft template, hydrochloric acid as a catalyst, and distilled water as a solvent. Then, mesoporous carbons were obtained via autoclave method at low temperature (60 °C) and then carbonization at a relatively low temperature (600 °C), respectively. X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) analyses revealed that the porous carbons with a mesophase pitch content of approximately 10 wt% showed a highly ordered hexagonal mesostructure with a highly uniform pore size of ca. 5.0 nm. In addition, the mesoporous carbons prepared by self-assembly and low-temperature autoclave methods exhibited the amorphous or crystalline carbon structures with higher specific surface area (SSA) of 756 m2/s and pore volume of 0.63 cm3/g, depending on the synthesis method. As a result, mesoporous carbons having a high SSA were successfully prepared by changing the mixing ratio of mesophase pitch and phenolic resin. The electrochemical properties of as-obtained mesoporous carbon materials were investigated. Further, the OMC-meso-10 electrode delivered the maximum SC of about 241 F/g at an applied current density of 1 A/g, which was higher than those of the MC-10 (~104 F/g) and OMC-20 (~115 F/g).