Hierarchically porous N‐doped carbon nanofibers derived from ZIF ‐8/ PAN composites for benzene adsorption

Flexible Phase Change Materials with High Energy Storage Density Based on Porous Carbon Fibers

Phase change fibers (PCFs) can effectively store and release heat, improve energy efficiency, and provide a basis for a wide range of energy applications. Improving energy storage density and preserving flexibility are the primary issues in the efficient manufacture and application development of PCFs. Herein, we have successfully fabricated a suite of flexible PCFs with high energy storage density, which use hollow carbon fibers (HCFs) encapsulated phase change materials (PCMs) to provide efficient heat storage and release, thereby enhancing energy efficiency and underpinning a broad range of energy applications. The flexible HCF/LA PCFs with high energy density were made by impregnating a small molecule LA solution, whereas the precursor of the PAN/ZIF-67 composite fibers was created by electrospinning. These PCFs have a high loading capacity for lauric acid (LA), demonstrating a 92% load percentage and a 153 J g-1 phase change enthalpy value. The effects of doping quantity (ZIF-67), fiber orientation, pre-oxidation treatment, and particle size on the morphological and structural characteristics of HCFs, as well as the impact of HCFs' pore structure on PCM encapsulation, were investigated. It was found that the oriented fiber structure serves to reduce the likelihood of fracture and breakage of precursor fibers after carbonization, whilst the gradient pre-oxidation can maintain the original fiber morphology of the fibers after carbonization. These findings establish a solid theoretical foundation for the design and production of high-performance flexible porous carbon nanofiber wiping phase change composites.

Hierarchical porous carbon nanofibrous membranes with elaborated chemical surfaces for efficient adsorptive removal of volatile organic compounds from air

Volatile organic compounds (VOCs) in the air pose great health risks to humans and the environment. Adsorptive separation technology has proven effective in mitigating VOC pollution, with the adsorbent being the critical component. Therefore, the development of highly efficient adsorbent materials is crucial. Carbon nanofibers, known for their physical-chemical stability and rapid adsorption kinetics, are promising candidates for removing VOCs from the air. However, the relatively simple porous structures and inert surface chemical properties of traditional carbon nanofibers present challenges in further enhancing their application performance further. Herein, a hierarchical porous carbon nanofibrous membrane was prepared using electrospinning technology and a one-step carbonization & activation method. Phenolic resin and polyacrylonitrile were used as co-precursors, with silica nanoparticles serving as the dopant. The resulting membrane exhibited a specific surface area of up to 1560.83 m2/g and surfaces rich in functional O-/N- groups. With a synergistic effect of developed micro- and meso-pores and active chemical surfaces, the carbon nanofibrous membrane demonstrated excellent adsorption separation performance for various VOCs, with comparable adsorption capacities and fast kinetics. Moreover, the membrane displayed remarkable reusability and dynamic adsorption performance for different VOCs, indicating its potential for practical applications.

Efficient extraction based on a polydimethylsiloxane/bimetallic ZnCo-MOF carbonization sponge coupled with GC-MS for the rapid analysis of volatile compounds in cumin

A novel porous polydimethylsiloxane/bimetallic ZnCo-MOF carbonization (PDMS/ZnCo-MOF@C) sponge was successfully fabricated, followed by its utilization in GC-MS for the high efficiency extraction and determination of volatile compounds in cumin. The PDMS/ZnCo-MOF@C sponge exhibits outstanding properties with a considerable adsorption capacity, high surface area, and large pore volume and has shown potential as an ideal adsorbent for the separation and preconcentration of trace volatile compounds. The effect of different parameters on the extraction efficiency were investigated. Excellent analytical performances were achieved for the representative compounds (β-pinene, p-cymene, γ-terpinene, cuminaldehyde, and linalyl acetate), including wide linearity (2.31-440.1 ng) with high correlation coefficients (R2 ≥ 0.9979), low LODs (1.02-3.11 ng) and LOQs (2.45-7.08 ng), and satisfactory precision (intra-day RSDs ≤ 2.89% and inter-day RSDs ≤ 4.14%). The optimal method was applied for the analysis of cumin from different regions and 44 volatile compounds were identified. The correlation between the different regions of cumin and volatile compounds was explored using multivariate statistical analysis. These results demonstrated that PDMS/ZnCo-MOF@C is an efficient, simple and sensitive material for use in the pretreatment technique for the determination of the volatile compounds in aromatic plants.

Preparation of ZIF-8/PAN composite nanofiber membrane and its application in acetone gas monitoring

Znic-based metal-organic framework materials (ZIF-8) show great potential and excellent performance in the fields of sensing and catalysis. However, powdered metal-organic framework makes it easy to lose in the process of application. Herein, we use a simple blending electrostatic spinning method to combine ZIF-8 particles with polyacrylonitrile (PAN) nanofibers. ZIF-8/PAN composite nanofiber membrane. The ZIF-8/PAN nanofiber membrane is characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and N₂adsorption-desorption. The results show that the ZIF-8/PAN nanofiber membrane has the characteristic peaks of XRD and FTIR, which are consistent with those of simulated ZIF-8. The specific surface area of ZIF-8/PAN nanofiber membrane increases from 13.5371 to 711.4171 m²g^-1due to the introduction of ZIF-8 particles. The sensor using the nanofiber membrane as the gas sensing layer shows good response and linear correlation to different concentrations of acetone gas. The minimum detection limit of the sensor for acetone is 51.9 ppm. The blank control shows that the response of the sensor to acetone is mainly due to the introduction of ZIF-8 particles. In addition, the sensor also shows a good cyclic response to acetone.

Recent Progress of the Preparation and Application of Electrospun Porous Nanofibers

Electrospun porous nanofibers have gained a lot of interest recently in various fields because of their adjustable porous structure, high specific surface area, and large number of active sites, which can further enhance the performance of materials. This paper provides an overview of the common polymers, preparation, and applications of electrospun porous nanofibers. Firstly, the polymers commonly used to construct porous structures and the main pore-forming methods in porous nanofibers by electrospinning, namely the template method and phase separation method, are introduced. Secondly, recent applications of electrospun porous nanofibers in air purification, water treatment, energy storage, biomedicine, food packaging, sensor, sound and wave absorption, flame retardant, and heat insulation are reviewed. Finally, the challenges and possible research directions for the future study of electrospun porous nanofibers are discussed.