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.

Utilization of an aqueous two-phase emulsification to prepare bimodal porous cellulose monolith for efficient adsorption of bovine serum albumin

Cellulose monolith has garnered significant interest in the field of biochromatography, which lies in its interconnected porous structure, large surface area and biocompatibility. In this context, we propose a novel approach for preparing cellulose monoliths using an aqueous two-phase system devoid of any organic solvents and surfactants. In this strategy, emulsifying cellulose solution into PEG 20,000 solution gives bicontinuous aqueous phases and further porous cellulose monolith after regeneration of dissolved cellulose. And the macroporous channels are derived from the removal of the PEG 20,000 aqueous phase while the micropores are from the phase separation of the cellulose phase. Physical characterizations reveal the obtained cellulose monolith exhibits exceptional column permeability of 1.36 × 10-11 m2 and a substantial surface area of 39.34 m2/g. Furthermore, cellulose monolith is functionalized with diethyl ethylamine hydrochloride (DEAE-HCl) to evaluate its potential as an anion adsorbent. Experimental results reveal that the DEAE-modified cellulose monolith possesses of adsorptive capacity of 316.58 mg/g of bovine serum albumin, along with fast adsorption kinetic. This study introduces an innovative strategy for fabricating porous cellulose monoliths tailored for biochromatography applications.

Shape-Memory Materials via Electrospinning: A Review

This review aims to point out the importance of the synergic effects of two relevant and appealing polymeric issues: electrospun fibers and shape-memory properties. The attention is focused specifically on the design and processing of electrospun polymeric fibers with shape-memory capabilities and their potential application fields. It is shown that this field needs to be explored more from both scientific and industrial points of view; however, very promising results have been obtained up to now in the biomedical field and also as sensors and actuators and in electronics.

Electrospun Nanofibers for Chemical Separation

The separation and purification of specific chemicals from a mixture have become necessities for many environments, including agriculture, food science, and pharmaceutical and biomedical industries. Electrospun nanofiber membranes are promising materials for the separation of various species such as particles, biomolecules, dyes, and metals from liquids because of the combined properties of a large specific surface, light weight, high porosity, good connectivity, and tunable wettability. This paper reviews the recent progress in the design and fabrication of electrospun nanofibers for chemical separation. Different capture mechanisms including electrostatic, affinity, covalent bonding, chelation, and magnetic adsorption are explained and their distinct characteristics are highlighted. Finally, the challenges and future aspects of nanofibers for membrane applications are discussed.

Ternary Composite of Co-Doped CdSe@electrospun Carbon Nanofibers: A Novel Reusable Visible Light-Driven Photocatalyst with Enhanced Performance

In this work, flexible ternary composites of cobalt-doped cadmium selenide/electrospun carbon nanofibers (Co-CdSe@ECNFs) for photocatalytic applications were fabricated successfully via electrospinning, followed by carbonization. For the fabrication of the proposed photocatalysts, Co-CdSe nanoparticles were grown in situ on the surface of ECNFs during the carbonization of precursor electrospun nanofibers obtained by dispersing Se powder in the electrospinning solution of polyacrylonitrile/N,N-Dimethylformamide (PAN/DMF) containing Cd2+ and Co2+. The photocatalytic performance of synthesized samples is investigated in the photodegradation of methylene blue (MB) and rhodamine B (RhB) dyes. Experimental results revealed the superior photocatalytic efficiency of Co-CdSe@ECNFs over undoped samples (CdSe@ECNFs) due to the doping effect of cobalt, which is able to capture the photogenerated electrons to prevent electron–hole recombination, thereby improving photocatalytic performance. Moreover, ECNFs could play an important role in enhancing electron transfer and optical absorption of the photocatalyst. This type of fabrication strategy may be a new avenue for the synthesis of other ECNF-based ternary composites.

Highly Flexible, Efficient, and Sandwich-Structured Infrared Radiation Heating Fabric

Controlling thermal energy is one of the biggest concerns along with the progress of human civilization for thousands of years. Current thermal comfort devices are mainly based on materials that are bulky, rigid, and heavy, largely limiting their widespread practical applications. It still remains a challenge to develop highly lightweight, flexible, and efficient electrical heaters for personal thermal management and local climate control. In this work, we present a high-performance composite infrared radiation heating fabric (IRHF), which mainly consists of two layers of poly(ethylene terephthalate) (PET) fabrics and one sandwiched layer of carbon nanofibers embedded with different inorganic nanoparticles. A copper electrode sheet was connected with the carbon nanofibers to form a conductive heating circuit. The permanent spontaneous polarization of both carbon nanofibers and infrared radiation nanoparticles can facilitate an enhanced current in the heater by creating an additional electrical field, which results in a fast electrothermal response and favorable heat preservation. The constructed IRHF could achieve an increase in the temperature to 43 °C from room temperature in 1 min under a voltage of 30 V, with an electrothermal conversion efficiency up to 78.99%. With a collection of compelling features such as good thermal stability, excellent flexibility and breathability, and high electrical conductivity and energy conversion efficiency, the fabricated sandwich-structured IRHF can open up new opportunities to develop smart heating textiles and wearable heating clothes in many fields.

Electrospun carbon nanofibers with multi-aperture/opening porous hierarchical structure for efficient CO2 adsorption

HYPOTHESIS

Carbonaceous materials are believed to be excellent source for developing essential vessels for carbon dioxide (CO₂) adsorption. However, most of the carbonaceous materials used for CO₂ capture have particle form, which is hard to recycle and also may cause choking of the gas pipes. Additionally, they also either require chemical activation or attachment of any functional groups for proficient CO₂ capture. Thus, facile fabrication of multi-aperture porous carbon nanofiber (CNF) based CO₂ sorbent via combination of three simple steps of electrospinning, washing, and carbonization, may be an effective approach for developing efficient sorbents for CO₂ capture.

EXPERIMENT

PAN/PVP composite solution was electrospun, PVP was used as pore forming template and PAN was opted as nitrogen rich precursor for carbon during electrospinning process. Selective removal of PVP from the electrospun PAN/PVP fiber matrix prior to carbonization generated highly rough and extremely porous PAN nanofibers, which were then carbonized to develop multi-aperture/opening porous carbon nanofibers (PCNF) with ultra-small pores with average pore diameter of ~0.71 nm.

FINDINGS

Synthesized PCNF exhibited high CO₂ gas selectivity (S = 20) and offered superior CO₂ adsorption performance of 3.11 mmol/g. Moreover, no apparent change in mass for up to 50 cycles of CO₂ adsorption/desorption unveil the long-term stability of synthesized PCNF, making them a potential candidate for CO₂ adsorption application.

Porous, flexible, and core-shell structured carbon nanofibers hybridized by tin oxide nanoparticles for efficient carbon dioxide capture

HYPOTHESIS

Carbon based nanofibrous materials are considered to be promising sorbents for the CO₂ capture and storage. However, the precise control of porous structure with flexibility still remains a challenging task. In this research, we report a simple strategy to develop tin oxide (SnO₂) embedded, flexible and highly porous core-shell structured carbon nanofibers (CNFs) derived from polyacrylonitrile (PAN)/polyvinylidene fluoride (PVDF) core-shell nanofibers.

EXPERIMENT

PAN/PVDF core-shell solutions were electrospun using co-axial electrospinning process. The as spun PAN core, and PVDF shell, with an appropriate amount of SnO₂, fibers were stabilized followed by carbonization to develop SnO₂ embedded highly porous and flexible core-shell structured CNFs.

FINDINGS

The optimized CNFs membrane shows a prominent CO₂ capture capacity of 2.6 mmol g^-1 at room temperature, excellent CO₂ selectivity than N₂, and a remarkable cyclic stability. After 20 adsorption-desorption cycles, the CO₂ capture capacity retains >95% of the preliminary value showing the long-term stability and practical worth of the final product. The loading of SnO₂ nanoparticles in the carbon matrix not only enhanced the thermal stability of the precursor nanofibers, their surface characteristics, and porous structure to capture CO₂ molecules, but also improves the flexibility of the CNFs by serving as a plasticizer for single-fiber-crack connection. Meaningfully, the flexible SnO₂ embedded core-shell CNFs with excellent structural stability can prevail the limitations of annihilation and collapse of structures for conventional adsorbents, which makes them strongly useful and applicable. This research introduces a new route to produce highly porous and flexible materials as solid adsorbents for CO₂ capture.

Flexible Fe3O4@Carbon Nanofibers Hierarchically Assembled with MnO2 Particles for High-Performance Supercapacitor Electrodes

Increasing use of wearable electronic devices have resulted in enhanced demand for highly flexible supercapacitor electrodes with superior electrochemical performance. In this study, flexible composite membranes with electrosprayed MnO₂ particles uniformly anchored on Fe₃O₄ doped electrospun carbon nanofibers (Fe₃O₄@CNF_Mn) have been prepared as flexible electrodes for high-performance supercapacitors. The interconnected porous beaded structure ensures free movement of electrolyte within the composite membranes, therefore, the developed supercapacitor electrodes not only offer high specific capacitance of ~306 F/g, but also exhibit good capacitance retention of ~85% after 2000 cycles, which certify that the synthesized electrodes offer high and stable electrochemical performance. Additionally, the supercapacitors fabricated from our developed electrodes well maintain their performance under flexural stress and exhibit a very minute change in specific capacitance even up to 180° bending angle. The developed electrode fabrication strategy integrating electrospinning and electrospray techniques paves new insights into the development of potential functional nanofibrous materials for light weight and flexible wearable supercapacitors.

Protein mediated textile dye filtration using graphene oxide–polysulfone composite membranes

Protein mediated textile dye filtration using graphene oxide (2%)–polysulfone composite membranes is studied for which the maximum rejection was recorded at pH = 2.