Graphene Oxide Nanofibers Research Articles

Nanotechnology in Lithium-Sulfur Batteries: Addressing the Challenges in Battery Cycle Life and Safety

Lithium-sulfur (Li-S) batteries, with their high energy density and affordable material prices, are a viable alternative to ordinary lithium-ion batteries, especially for electric cars. Their actual application is limited by challenges such as substantial volume expansion, low electrical conductivity, and the polysulfide shuttle effect, despite their advantages. This research investigates how incorporating nanomaterials into Li-S battery cathodes, anodes, and electrolytes might improve battery performance and analyzes the potential of nanotechnology to address these problems. The application of metal oxides, graphene oxide, and carbon nanofibers to improve the stability and conductivity of sulfur cathodes is covered. Additionally, it examines anode protection strategies using nanocoating and protective layers to inhibit dendrite growth and improve safety. The incorporation of nanoparticles in electrolytes to improve ionic conductivity and reduce side reactions is also analyzed. Despite the progress, challenges such as the polysulfide shuttle effect and volume changes remain. The paper concludes with recommendations for future research to develop commercially viable Li-S batteries with higher capacity, longer lifespan, and improved safety.

Fabrication of composite RGD-tagged poly(lactic acid)-graphene oxide nanofiber containing bone-forming peptide-3 loaded-dendritic silica nanoparticles for bone regeneration in rabbit

In the current study, polylactic acid (PLA)/graphene oxide (GO) based composite scaffolds were fabricated by electrospinning method and then covalently modified with bone-forming peptide-3 (BFP-3)-loaded thiol-functionalized dendritic mesoporous silica nanoparticles (BFP-3@HS-DMSNs) and RGD. In this regard, PLA electrospinning nanofibers and composite of PLA/GO electrospinning nanofibers containing 0.02, 0.01, 0.04, 0.1, 0.2 % of GO were prepared and characterized in terms of mechanical strength, nanofibers diameter, thermal stability, crystallinity, specific surface area, total pore volume and cell adhesion properties. Among the prepared composites, PLA nanofibers containing 0.02 % GO demonstrated superior mechanical and morphological characteristics along with better cell adhesion for mesenchymal stem cell. Then, the PLA/0.02 %GO nanofiber was treated with plasma and consequently modified with N-(2-aminoethyl)maleimide linker which was applied for Cys-RGD and BFP-3@HS-DMSNs conjugation. The obtained results showed desirable adhesion of PLA/0.02 %GO nanofiber after incorporation of RGD (5 % of maleimide groups of the linker) and DMSNs which significantly increase cell adhesion potency (1.53 folds). By incorporation of BFP-3@HS-DMSNs (equivalent to 0.1 µg of BFP-3) to the RGD-tagged PLA/0.02 %GO nanofiber, the scaffold demonstrated better cytocompatibility and MSC differentiation to osteoblast based on biomineralization assay via alizarin red (4.2 folds) and alkaline phosphatase activity (1.7 folds) tests. In preclinical stage, after skull defect creation in rabbits, 5 treatments groups comprising PLA/0.02 %GO nanofiber, PLA/0.02 %GO/DMSNs, PLA/0.02 %GO/DMSNs/Cys-RGD, PLA/0.02 %GO/BFP-3@DMSNs and PLA/0.02%GO/BFP-3@DMSNs/Cys-RGD were used for bone regeneration in skull defects. After 3 months, the implantation of PLA/0.02GO/BFP-3@DMSNs/Cys-RGD showed higher bone regeneration based on CBCT imaging (18.875 mm2 bone formed area) in comparison with other treatment groups. This hybrid multimodal platform is purposely organized interactive processes which lead to potential bone regeneration.

Formamidinium Lead Iodide‐Based Perovskite Solar Cell Fabrication With an Electrospun‐Reduced Graphene Oxide Back Electrode: A Novel Approach

AbstractIn this work, low‐cost and simple structure perovskite solar cells (PSCs) were fabricated using formamidinium lead iodide (FAPbI3) as the light absorber and reduced graphene oxide nanofibers (rGO NFs) as the counter electrode (CE). The FAPbI3 light absorber was prepared using a two‐step solution process, whereas the rGO NFs were synthesized through a simple electrospinning method. The as‐prepared FAPbI3 and rGO NFs were characterized by high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) pattern analysis. The surface morphology of the as‐prepared FAPbI3 and rGO NFs showed crystalline and bead‐free fiber structures, as confirmed by HRTEM and FESEM image analysis. The AFM topographical images of FAPbI3 and rGO NFs further reveal the crystalline and fiber structures. XRD pattern analysis confirmed the cubic crystalline phase of FAPbI3 and the graphitic nature of rGO NFs. From the electrochemical impedance spectroscopy studies, the PSC assembled with the FAPbI3 light absorber and rGO NFs‐based CE demonstrated an electrical conductivity of 3.64 × 10−4 S cm−1. The fabricated PSC device achieved an efficiency of 8.78% compared to the 7.49% efficiency of the device with a sputtered gold CE. This work uniquely integrates advanced materials, cost‐effective manufacturing, and enhanced efficiency in PSCs using FAPbI3 light absorbers and rGO NFs, addressing key challenges in cost and sustainability in solar technology.

Smart Carbon Fiber-Reinforced Polymer Composites for Damage Sensing and On-Line Structural Health Monitoring Applications.

High electrical conductivity, along with high piezoresistive sensitivity and stretchability, are crucial for designing and developing nanocomposite strain sensors for damage sensing and on-line structural health monitoring of smart carbon fiber-reinforced polymer (CFRP) composites. In this study, the influence of the geometric features and loadings of carbon-based nanomaterials, including reduced graphene oxide (rGO) or carbon nanofibers (CNFs), on the tunable strain-sensing capabilities of epoxy-based nanocomposites was investigated. This work revealed distinct strain-sensing behavior and sensitivities (gauge factor, GF) depending on both factors. The highest GF values were attained with 0.13 wt.% of rGO at various strains. The stability and reproducibility of the most promising self-sensing nanocomposites were also evaluated through ten stretching/relaxing cycles, and a distinct behavior was observed. While the deformation of the conductive network formed by rGO proved to be predominantly elastic and reversible, nanocomposite sensors containing 0.714 wt.% of CNFs showed that new conductive pathways were established between neighboring CNFs. Based on the best results, formulations were selected for the manufacturing of pre-impregnated materials and related smart CFRP composites. Digital image correlation was synchronized with electrical resistance variation to study the strain-sensing capabilities of modified CFRP composites (at 90° orientation). Promising results were achieved through the incorporation of CNFs since they are able to form new conductive pathways and penetrate between micrometer-sized fibers.

Innovative use of nanomaterials for improving performance of asphalt binder and asphaltic concrete: a state-of-the-art review

ABSTRACT Rising costs of constructing and maintaining asphaltic concrete pavements present a challenge requiring an alternative solution. Nanomaterials can be cost-effectively integrated with asphalt binder to provide beneficial effects for asphaltic concrete mixture. This paper investigated seven different types of nanomaterials, namely nanoclay, carbon nanotube, nanosilica, nano-titanium dioxide, nano-zinc oxide, graphene oxide, and carbon nanofiber by examining their production methods, benefits, applications, and limitations based on the data available in published literature. Challenges and limitations discussed include economic, production, and blending problems, some of which are due to the lack of research on the topic. This study provides a framework from which the pavement engineering community can conduct experimental research on nanomaterials for applications in asphaltic concrete pavements. The review of previous studies reveals that new asphalt binders and asphaltic concrete mixtures incorporating nanomaterials can be developed for improved performance of flexible pavements. It is expected that further research can be devoted to overcoming the current challenges faced by aging transportation infrastructure through use of nanomaterials in asphalt binder and asphaltic concrete. Above all, research gaps in the present state of knowledge have been identified and certain recommendations are given for future investigations.

Exploring various carbon nanomaterials-based electrodes modified with polymelamine for the reagentless electrochemical immunosensing of Claudin18.2

Claudin18.2 (CLDN18.2) is a tight junction protein often overexpressed in various solid tumors, including gastrointestinal and esophageal cancers, serving as a promising target and potential biomarker for tumor diagnosis, treatment assessment, and prognosis. Despite its significance, no biosensor has been reported to date for the detection of CLDN18.2. Here, we present the inaugural immunosensor for CLDN18.2. In this study, an amine-rich conducting polymer of polymelamine (PM) was electrografted onto different carbon nanomaterial-based screen-printed electrodes (SPEs), including carbon (C), graphene (Gr), graphene oxide (GO), carbon nanotube (CNT), and carbon nanofiber (CNF) via cyclic voltammetry. A comparative study was performed to explore the best material for the preparation of the PM-modified electrodes to be used as in-situ redox substrate for the immunosensor fabrication. The surface chemistry and structural features of pristine and PM-deposited electrodes were analyzed using Raman and scanning electron microscopy (SEM) techniques. Our results showed that the PM deposited on Gr and CNT/SPEs exhibited the most significant and stable redox behavior in PBS buffer. The terminal amine moieties on the PM-modified electrode surfaces were utilized for immobilizing anti-CLDN18.2 monoclonal antibodies via N-ethyl-N′-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide chemistry to construct the electrochemical immunosensor platform. Differential pulse voltammetry-based immunosensing of CLDN18.2 protein on BSA/anti-CLDN18.2/PM-Gr/SPE and BSA/anti-CLDN18.2/PM-CNT/SPE exhibited excellent selectivity against other proteins such as CD1, PDCD1, and ErBb2. The limits of detection of these two immunosensor platforms were calculated to be 7.9 pg/mL and 0.104 ng/mL for the CNT and Gr immunosensors, respectively. This study demonstrated that the PM-modified Gr and CNT electrodes offer promising platforms not only for the reagentless signaling but also for covalent immobilization of biomolecules. Moreover, these platforms offer excellent sensitivity and selectivity for the detection of CLDN18.2 due to its enhanced stable redox activity. The immunosensor demonstrated promising results for the sensitive detection of CLDN18.2 in biological samples, addressing the critical need for early gastric cancer diagnosis.

3D monolithic composites TiO2/HKUST-1/RGO@melamine foam with improved surface mass transfer for efficient photocatalytic degradation of toluene gas

Currently, photocatalytic technology mostly uses powdered TiO2 catalysts, which are not conducive to recycling, limit the contact between volatile organic compounds (VOCs) and the photocatalyst, and result in lower mass transfer efficiency in gas-solid reactions. Meanwhile, TiO2 catalysts including the electrospun TiO2 nanofibers with hydrophilic surfaces are not favorable for the infiltration and adsorption of non-polar VOCs. To solve these problems, in this work, the monolithic composites TiO2/HKUST-1/RGO@melamine foam (named MRTH) with improved surface mass transfer composed of metal-organic framework (HKUST-1), graphene oxide (GO) and electrospun TiO2 nanofibers was designed. The metal-organic framework HKUST-1 plays a role in promoting the adsorption of toluene, while the reduced graphene oxide (RGO) facilitates the infiltration of non-polar molecules on the surface of the composite and has better electron transport capability. A type II heterojunction between the electrospun TiO2 nanofibers and HKUST-1 formed in the monolithic composites suppresses the recombination of electron-hole pairs and extends their lifespan. Comparing with the bare electrospun TiO2 nanofibers, the MRTH foam composites exhibit a wider light absorption range, hydrophilic and oleophobic properties and a higher separation efficiency of photogenerated carriers. In 90 min of dark adsorption, the removal rate of toluene over MRTH-8 was 52.32 %, while under irradiation by xenon lamp for 150 min, the removal rate over MRTH-8 reached 90.15 %. The amount of monolithic foam composites can also be easily adjusted in the reactor to achieve the best possible removal of the contaminant. The prepared composite materials have been characterized in detail, and the possible mechanisms have also been discussed. The foam composites prepared in this work have high catalytic activity and gas-solid reaction mass transfer efficiency, so they have wide practical application prospects in the field of VOCs abatement.

Constructing graphene-based aerogel with bi-continuous interpenetrating networks as a multi-functional microwave absorber

The design of three-dimensional networks in graphene-based aerogels is an effective strategy for fabricating a lightweight microwave absorber with strong absorption and broad effective bandwidth. Herein, a multi-functional aerogel with bi-continuous interpenetrating networks comprised of reduced graphene oxide (RGO) and cellulose nanofiber (CNF) was developed via an “ice-dissolving” (freezing and solvent exchange) and subsequent annealing strategy. Different from the conventional step-by-step construction of two independent networks, the bi-continuous interpenetrating networks were simultaneously built in a one-step freezing process. Notably, the network structure of the aerogel can be tuned by adjusting the concentration of CNF (CCNF) during the freezing stage. When the CCNF increased from 2 to 8 wt%, the network structure transitioned from a single three-dimensional RGO skeleton to ordered bi-continuous interpenetrating networks, and then to a disordered CNF/RGO mixed network. The mutual contributions from the RGO skeleton and CNF network endowed the aerogel (14.96 mg cm−3) with improved conduct loss and optimized characteristic impedance, leading to an excellent microwave absorption capacity. Consequently, the aerogel achieved a maximum reflection loss of −68.3 dB and an effective bandwidth of 6.9 GHz, respectively. Moreover, the unique network structure also enabled the sample to have superior noise absorbing performance (normalized absorption coefficient of 0.894 in 250–6300 Hz) and good structural stability. This strategy provides a facile avenue for constructing multi-functional aerogels with bi-continuous interpenetrating networks for both microwave absorption and noise absorption applications.

Desferrioxamine-Laden Nanofibrous Scaffolds with Efficient Angiogenesis for Accelerating Diabetic Wound Healing.

Delayed diabetic wound healing is one of the clinical difficulties, the main reason is the limited angiogenesis ability. Deferriamine (DFO) is an iron chelating agent that can induce angiogenesis, but its application is limited due to its short half-life. Increasing the load and slow release performance of desferriamine is beneficial to accelerate diabetic wound healing. In this study, we developed collagen (Col)-graphene oxide (GO) and (1% w/w) DFO-loaded nanofiber electrospinning scaffolds (DCG) using the electrospinning technique. We tested the physicochemical properties, drug release performance, and vascularization biological function of the scaffolds, and finally evaluated the promotion of full-thickness wound healing in the diabetic rat models. The results showed that DCG scaffolds have good mechanical properties and water-holding capacity and can release DFO continuously for 14 days. In vitro, the novel DCG scaffold exhibited good biocompatibility, with the up-regulation at the gene level of VEGF and its regulator HIF-1α, promoters of angiogenesis. This was verified in vivo, as the scaffold enhanced granulation tissue formation and improved neovascularization, thereby accelerating wound healing when applied to full-thickness defects on the back of diabetic rats. The DCG nanofiber scaffold prepared in this study has good biocompatibility and vascularization ability, and improves the microenvironment in vivo, and has a good application prospect in diabetic wound repair.

Boosting solar vapor generation and desalination by low-cost reduced graphene oxide/cellulose aerogel and multiple energy utilization

Solar interfacial vapor generation provides one of promising pathways for seawater desalination and wastewater treatment with minimized carbon footprint. There are still great challenges in architecting low-cost solar evaporators for rapid water transfer channels and high-throughput evaporation rate. Herein, an aerogel with reduced graphene oxide and cellulose nanofibers (rGC) was fabricated by one step self-assembly method. The rGC possessed excellent light absorption, superhydrophilic ability, and reduced energy requirement of water evaporation. The evaporation rate of rGC-3 (height of 3 cm) achieved 3.19 kg m−2 h−1 with the evaporation efficiency of 114.3% under 1 sun irradiation. The suspended vapor was timely diffused by directional convection, so as to minimize the stagnation of vapor in openly channels and continuously harvest additional environmental energy. The water evaporation behavior was improved to 9.40 kg m−2 h−1 under a convective flow of 2.5 m s−1, well beyond 200.3% of non-convective condition. Additionally, the three-dimensional rGC-3 consistently evaporated in 3.5 wt% brine and the evaporation rate kept at 8.61 - 9.39 kg m−2 h−1. In the outdoor solar water desalination, rGC-3 had excellent desalination behavior and evaporative performance in weak sunlight and relative low temperature. The realization of enhanced evaporation rate, overall seawater purification capability, and high cost-effectiveness of the nanofiber aerogel provide a new inspiration for designing high-throughput solar interfacial evaporator.

Fabrication and In Vitro Characterization of Polycaprolactone/Graphene Oxide/Collagen Nanofibers for Myocardial Repair

AbstractThis study is focused on fabricating tissue‐engineered electrospun nanofibers that contain polycaprolactone (PCL), graphene oxide (GO), and collagen (COL) to get an alternative treatment for cardiac injuries. GO (1.5 wt%) is used to support the contraction‐elongation of cardiomyocytes by improving electrical stimulation. The COL (1, 3, and 5 wt%) is the main component of the myocardial extracellular matrix have led to their frequent use in cardiac tissue engineering (CTE). The scanning electron microscope (SEM) images show the homogeneous and bead‐free morphologies of the nanofibers. Adding a high amount (3% and 5%) of COL decreases the tensile strength value of 17% PCL/1.5% GO nanofiber. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐Diphenyltetrazolium Bromide (MTT) assay demonstrates that the COL addition increases cell viability compared to that in 17% PCL/1.5% GO nanofibers on the third day. The response of the nanofibers to alternating current (AC) signal is studied between the frequencies 40 and 105 Hz. The direct current (DC) conductivity values of the films are determined to be between 1.10−10 and 6.10−10 S m−1 at 25 °C. The AC conductivity values show frequency‐dependent behavior. Among the PCL/GO‐based electrospun nanofibers, 17% PCL/1.5% GO/5% COL nanofiber shows greater DC and AC conductivity than 17% PCL/1.5% GO nanofiber.

Cesium lead iodide-decorated two-dimensional titanium dioxide/reduced graphene oxide nanofiber composites as photoanodes for inorganic perovskite solar cells

In this study, we developed photoanode materials based on inorganic cesium lead iodide (CsPbI3)-decorated two-dimensional titanium dioxide-reduced graphene oxide nanofibers (TiO2/rGO NFs22TiO2/rGO NFs - titanium dioxide-reduced graphene oxide nanofibers.) for perovskite solar cells (PSCs). CsPbI3 was prepared by a two-step solution process and TiO2/rGO NFs were prepared using the electrospinning method. The influence of the as-fabricated TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite on their optical, surface, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet–visible–near-infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy analyses. XRD analysis of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite showed a crystalline nature with cubic and anatase crystal faces. The surface morphology of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite appeared as a beat-free fiber with a polycrystalline nature. The chemical oxidative states and electronic structures of the electrospun TiO2/rGO NFs were determined by X-ray photoelectron spectroscopy analysis. PSCs device were assembled with TiO2 NFs, TiO2/rGO NFs as photoanode, 2,2′,7,7′-Tetrakis(N,N-di-P-methoxyphenylamine)− 9,9′-spirobifluorene (Spiro–OMeTAD) as hole transport materials, sputtered gold chloride as back electrode (counter electrode). In addition, the CsPbI3 perovskite coated on the electrospun TiO2 and TiO2/rGO NF photoanodes exhibited electrical conductivities of 1.352 × 10−3 and 1.650 × 10−3 S cm−1. Finally, power conversion efficiency of TiO2/rGO NFs (6.38 %) was achieved, which was significantly higher than that of conventional TiO2 NFs (5.54 %)-based devices.

High-Performance Flexible Zinc–Air Batteries Enabled by a Sodium Polyacrylate-Based Gel Electrolyte Containing Graphene Oxide and Cellulose Nanofibers

High-Performance Flexible Zinc–Air Batteries Enabled by a Sodium Polyacrylate-Based Gel Electrolyte Containing Graphene Oxide and Cellulose Nanofibers

Evaluation of contact angle and mechanical properties of resin monomers filled with graphene oxide nanofibers.

This in vitro study synthesized hybrid nanofibers embedded in graphene oxide (GO) and incorporated them into experimental resin composite monomers to evaluate their physical-mechanical properties. Inorganic-organic hybrid nanofibers were produced with precursor solutions of 1% wt. GO-filled Poly (d,l-lactide, PLA) fibers and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) characterized the morphology and chemical composition of the spun fibers. Resin composite monomers were developed and a total of 5% nanofibers were incorporated into the experimental materials. Three groups were developed: G1 (control resin monomers), G2 (resin monomers/PLA nanofibers), and G3 (resin monomers/inorganic-organic hybrid nanofibers). Contact angle (n=3), flexural strength (n=22), elastic modulus (n=22), and Knoop hardness (n=6) were evaluated. The mean of the three indentations was obtained for each sample. The normality of data was assessed by QQ Plot with simulated envelopes and analyzed by Welch's method (p<0.05). Overall, SEM images showed the regular shape of nanofibers but were non-aligned. Compositional analysis from EDS (n=6) revealed the presence of carbon and oxygen (present in GO composition) and Si from the functionalization process. The results of contact angle (°) and hardness (Kg/mm2) for each group were as follow, respectively: G1 (59.65±2.90; 37.48±1.86a), G2 (67.99±3.93; 50.56±1.03b) and G3 (62.52±7.40; 67.83±1.01c). The group G3 showed the highest Knoop hardness values (67.83 kg/mm2), and the flexural strength of all groups was adversely affected. The experimental resin composite composed of hybrid nanofibers with GO presented increased hardness values and hydrophilic behavior.

Simple design of Sn/reduced graphene oxide/carbon nanofibers ternary hybrids for lithium-ion batteries

Novel Sn/reduced graphene oxide/carbon nanofibers ternary hybrids have been designed via a facile one-step synthesis process. In the hybrids, Sn nanoparticles, uniformly sandwiched in the layers of reduced graphene oxide, are in good contact with carbon nanofibers. The ternary hybrids have demonstrated superior lithium storage performance to the Sn/reduced graphene oxide and Sn/carbon nanofibers binary hybrids. The reversible capacity of the ternary hybrids is 643 mAh g−1 after 90 cycles. Importantly, electrochemical impedance spectroscopy measurements confirm that the integration of Sn, reduced graphene oxide and carbon nanofibers can reduce the charge transfer resistance effectively.

The impact of various carbon nanomaterials on the morphological, behavioural, and biochemical parameters of rainbow trout in the early life stages

With the increasing production and the number of potential applications of carbon nanomaterials, mainly from the graphene family, their release into the natural environment, especially to aquatic ecosystems, is inevitable. The aim of the study was to determine the effects of various carbon nanomaterials (graphene nanoflakes (GNF), graphene oxide (GO), reduced graphene oxide (RGO) and silicon carbide nanofibers (NFSiC) in the concentration of 4 mg L−1 on the early life stages of the rainbow trout Oncorhynchus mykiss. The survival rates of O. mykiss were not affected after 36 days of exposure to studied materials, except for RGO, which caused significant mortality of both embryos and larvae compared to the control conditions. Larvae exposed to GO and NFSiC were characterized by a smaller standard body length at hatch, whereas at the end of the experiment, the growth of fish exposed to all materials was accelerated, especially in GO and RGO treatment, in which higher body weight and length were accompanied by lower volume of the yolk sac. Neither the markers of the oxidative damage nor the antioxidant enzymes activities were significantly affected in embryos, newly hatched larvae and larvae after 26-day exposure to studied carbon nanomaterials. Also, no neurotoxic effect expressed by the activity of the whole-body acetylcholinesterase was observed. Nevertheless, the significant increase in the velocity and the overall activity of larvae exposed to GNF (not investigated after exposure to other materials) must be highlighted. The most pronounced effect of RGO might be connected with its large particle size, sharp edges, and the presence of TiO2 nanoparticles. The results indicate for the first time that various carbon nanomaterials potentially released into aquatic ecosystems may have serious developmental implications for the early life stages of salmonid fish.

Electrospinning of cellulose acetate/graphene/nanoclay nanocomposite for textile wastewater filtration

In this study, electrospinning technique was used to prepare cellulose acetate (CA) and graphene oxide (GO) nanofiber composites along with nanoclay (NC) for filtration applications. For this purpose, different contents of GO and NC were added to the CA solution, and the electrospinning process was optimized to produce the finest fiber. The morphology and crystalline structures of the resulting nanofiber composites were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. According to the obtained results, the CA (12%)/GO (1%)/NC (1%) nanofiber had the minimum mean fiber diameter and uniform diameter distribution among all electrospun fibers. TEM images showed good dispersion of the employed nanostructures (GO and NC) in the fibrous membranes. The results of the mechanical test revealed 24% improvement in the tensile strength of the nanocomposite fiber (CA/GO/NC) in comparison with CA fiber. Thermogravimetric analysis (TGA) indicated that the presence of GO and NC led to higher thermal stability than pristine polymeric fiber. XRD results confirmed the presence of both amorphous and crystalline CA in the optimized sample. The spectrophotometric analysis showed that the amount of dye absorption increased after adding GO and NC to CA. In conclusion, the produced fibrous nanocomposite can be used as a potential filter for color removal in the textile industry.

Wearable Dual-Signal NH3 Sensor with High Sensitivity for Non-invasive Diagnosis of Chronic Kidney Disease.

NH3 gas in human exhaled breath contains abundant physiological information related to human health, especially chronic kidney disease (CKD). Unfortunately, up to now, most wearable NH3 sensors show inevitable defects (low sensitivity, easy to be interfered by the environment, etc.), which may lead to misdiagnosis of CKD. To solve the above dilemma, a nanoporous, heterogeneous, and dual-signal (optical and electrical) wearable NH3 sensor mask is developed successfully. More specifically, a polyacrylonitrile/bromocresol green (PAN/BCG) nanofiber film as a visual NH3 sensor and a polyacrylonitrile/polyaniline/reduced graphene oxide (PAN/PANI/rGO) nanofiber film as a resistive NH3 sensor are constructed. Due to the high specific surface area and abundant NH3 binding sites of these two nanofiber films, they exhibit good NH3 sensing performance. However, although the visual NH3 sensor (PAN/BCG nanofiber film) is simple without the need of any detecting facilities and quite stable when temperature and humidity change, it shows poor sensitivity and resolution. In comparison, the resistive NH3 sensor (PAN/PANI/rGO nanofiber film) is of high sensitivity, fast response, and good resolution, but its electrical signal is easily interfered by the external environment (such as humidity, temperature, etc.). Considering that the sensing principles between a visual NH3 sensor and resistive NH3 sensor are significantly different, a wearable dual-signal NH3 sensor containing both a visual NH3 sensor and resistive NH3 sensor is further explored. Our data prove that the two sensing signals in this dual-signal NH3 sensor mask can not only work well without interference with each other but also complement each other to improve the sensing accuracy, indicating its potential application in non-invasive diagnosis of CKD.

High-performance cathode promoted by reduced graphene oxide nanofibers with well-defined interconnected meso-/micro pores for rechargeable Li-Se batteries

Highly conductive nanostructures comprising one-dimensional (1D) reduced graphene oxide (rGO) nanofibers (NFs) and bimodal pores i.e., meso-/micropores, as efficient cathode hosts (Bi-P-rGO) for Li–Se batteries were prepared. The highly conductive rGO matrix acts as a self-supporting skeleton to enhance the structural integrity of the nanostructure besides providing numerous conducting pathways for rapid charge transfer. Moreover, highly interconnected chain-like mesopores guarantee efficient electrolyte percolation, whereas the micropores offer highly active material impregnation. Correspondingly, Bi-P-rGO@Se as a high-performance cathode was visualized, which demonstrated an overall enhanced electrochemical performance such as excellent rate capability (up to 20.0C) and overwhelming long-term cycling stability (73% capacity retention at the end of 800cycles with an average capacity decay rate of just 0.03% per cycle at 0.5C rate). The exceptional electrochemical performance of the Bi-P-rGO@Se cathode can be attributed to its highly porous structure, which promises efficient electrolyte infiltration and diffusion of charged species, high active material utilization within micropores, availability of conductive pathways for fast charge transfer, and high structural integrity. Therefore, we anticipate that the structural and electrochemical results presented in this work will provide significant insights into the synthesis of high-performance porous and conductive nanostructures for a wide range of applications.

Antiviral properties of porous graphene, graphene oxide and graphene foam ultrafine fibers against Phi6 bacteriophage.

As the world has experienced in the Coronavirus Disease 2019 pandemic, viral infections have devastating effects on public health. Personal protective equipment with high antiviral features has become popular among healthcare staff, researchers, immunocompromised people and more to minimize this effect. Graphene and its derivatives have been included in many antimicrobial studies due to their exceptional physicochemical properties. However, scientific studies on antiviral graphene are much more limited than antibacterial and antifungal studies. The aim of this study was to produce nanocomposite fibers with high antiviral properties that can be used for personal protective equipment and biomedical devices. In this work, 10 wt% polycaprolactone-based fibers were prepared with different concentrations (0.1, 0.5, 1, 2, 4 w/w%) of porous graphene, graphene oxide and graphene foam in acetone by using electrospinning. SEM, FTIR and XRD characterizations were applied to understand the structure of fibers and the presence of materials. According to SEM results, the mean diameters of the porous graphene, graphene oxide and graphene foam nanofibers formed were around 390, 470, and 520 nm, respectively. FTIR and XRD characterization results for 2 w/w% concentration nanofibers demonstrated the presence of graphene oxide, porous graphene and graphene foam nanomaterials in the fiber. The antiviral properties of the formed fibers were tested against Pseudomonas phage Phi6. According to the results, concentration-dependent antiviral activity was observed, and the strongest viral inhibition graphene oxide-loaded nanofibers were 33.08 ± 1.21% at the end of 24 h.