Carbon Fiber Substrate Research Articles

Converting CO2 to multi-carbon products at >1 A/cm2 using gas diffusion electrode based on commercial materials via transfer process engineering

Cu-based gas diffusion electrodes for the electrocatalytic conversion of CO2 to high-value-added multi-carbon products is a promising technology. However, it is in urgent demand to develop high-efficiency electrode and electrolyzer to promote its poor reaction kinetics and product selectivity, which have seriously hindered its industrial application. Herein, the hydrophobicity property and the pore size distribution of microporous layer (MPL) and the hydrophobicity property of carbon fiber substrate (CFS) were studied to adjust electron transfer, CO2 transfer, and water transfer, which creates a microenvironment more suitable for the production of multi-carbon products. It is shown, by this strategy, ampere-level current density (1.36 A/cm2) is obtained using a gas diffusion electrode based entirely on commercially available materials, with partial current density of 0.697 A/cm2 and 0.885 A/cm2 for ethylene and C2+ products at −1.44V vs. RHE. Further characterizations show that the CO2 transfer via CFS and MPL to catalyst layer (CL) and water transfer determine CL local CO2 concentration and wettability to further influence the gas-liquid ratio and the coverage of *CO2, *H, and *CO on the catalyst surface to promote CC coupling and thus yield an optimal selectivity of C2+ products.

Fabrication of Porous Reduced Graphene Oxide Encapsulated Cu(OH)2 Core-shell Structured Carbon Fiber-Based Electrodes for High-Performance Flexible Supercapacitors.

To explore next-generation flexible supercapacitors, lightweight, superior conductivity, low cost, and excellent capacitance are the preconditions for practical use. However, subjected to unsatisfactory conductivity, limited surface areas, and poor porosity leading to long ion transport channels, carbon fiber (CF)-based flexible supercapacitors need to further boost the electrochemical properties. Hence, a porous reduced graphene oxide encapsulated Cu(OH)2 core-shell structured CF-based electrode was fabricated through a scalable approach. The inexpensive Cu(OH)2 nanoarrays were controllably grown in situ on a CF substrate, with residual Cu promoting conductivity. Porous graphene oxide (PrGO), which served as the shell, was realized by Ni nanoparticle etching, which not only provided more active sites for capacitance as well as shortened accessible pathways for the ion transport but also effectively alleviated the exfoliation of the internal active materials. Moreover, thanks to this distinctive core-shell architecture, the extra space between the outer PrGO layer and the internal ordered Cu(OH)2 nanoarrays provided increased space for capacitance storage. The assembled PrGO/Cu(OH)2/Cu@CF electrode exhibited an excellent areal capacitance, reaching up to 722 mF cm-2 at a current density of 0.5 mA cm-2, attributed to its superior structure and materials advantages. The resulting PrGO/Cu(OH)2/Cu@CF//AC//CF asymmetric flexible all-solid-state supercapacitor achieved a high energy density of 0.052 mWh cm-2 and exhibited long-term durability. This work proposes a low-cost and effective way to fabricate hierarchically structured electrodes for wearable CF-based supercapacitors.

Alkaline Water Splitting by Ni-Fe Nanoparticles Deposited on Carbon Fibre and Nickel-Coated Carbon Fibre Substrates

Alkaline Water Splitting by Ni-Fe Nanoparticles Deposited on Carbon Fibre and Nickel-Coated Carbon Fibre Substrates

Construction of a stable S-scheme NiSnO3/g-C3N4 heterojunction on activated carbon fibre for the degradation of glyphosate in water under flow condition

Creating light-harvesting heterojunctions as a photocatalyst is critical for efficiently treating organics-laden wastewater. Yet the materials stabilization and limited reusability hinder their practical applications. In this study, an S-scheme heterojunction in the Sn-based perovskite and g-C3N4 (gCN) composite, supported on an activated carbon fiber (ACF) substrate, is developed for glyphosate (GLP) degradation under water under flow conditions. The reusable NiSnO3-gCN/ACF photocatalyst was synthesized using a simple wet impregnation and calcination method. The supported photocatalyst achieved 99% GLP-removal at 4 mL/min water flowrate and 1.25 g/m2 of photocatalyst loading in ACF. The photocatalyst showed a stable structure and repeat photocatalytic performance across 5 cycles despite prolonged visible light exposure under flow conditions. The materials stability is attributed to the effective dispersion of NiSnO3-gC3N4 in ACF, preventing the photocatalyst from elution in water flow. Radical trapping experiment revealed the superoxide and hydroxyl radicals as the primary reactive species in the GLP-degradation pathway. A plausible S-scheme mechanism was proposed for heterojunction formation, based on the high resolution deconvoluted spectra of X-ray photoelectron spectroscopy and the radical trapping experimental results. The inexpensive Sn-based perovskite synthesized in this study is indicated as an alternative to Ti-based perovskites for wastewater remediation application.

Tensile Strain-Mediated Spinel Ferrites Enable Superior Oxygen Evolution Activity.

Exploring efficient strategies to overcome the performance constraints of oxygen evolution reaction (OER) electrocatalysts is vital for electrocatalytic applications such as H2O splitting, CO2 reduction, N2 reduction, etc. Herein, tunable, wide-range strain engineering of spinel oxides, such as NiFe2O4, is proposed to enhance the OER activity. The lattice strain is regulated by interfacial thermal mismatch during the bonding process between thermally expanding NiFe2O4 nanoparticles and the nonexpanding carbon fiber substrate. The tensile lattice strain causes energy bands to flatten near the Fermi level, lowering eg orbital occupancy, effectively increasing the number of electronic states near the Fermi level, and reducing the pseudoenergy gap. Consequently, the energy barrier of the rate-determining step for strained NiFe2O4 is reduced, achieving a low overpotential of 180 mV at 10 mA/cm2. A total water decomposition voltage range of 1.52-1.56 V at 10 mA/cm2 (without iR correction) was achieved in an asymmetric alkaline electrolytic cell with strained NiFe2O4 nanoparticles, and its robust stability was verified with a voltage retention of approximately 99.4% after 100 h. Furthermore, the current work demonstrates the universality of tuning OER performance with other spinel ferrite systems, including cobalt, manganese, and zinc ferrites.

Wire-type flexible micro-supercapacitor based on MOF-assisted sulfide nano-arrays on dendritic CuCoP and V2O5-polypyrrole/nanocellulose hydrogel

Wire/fiber-type micro-supercapacitors (micro-SCs) have great potentials in next-generation wearable and portable energy supply devices, due to their low weight, high flexibility, small size and excellent reliability. Herein, we designed 2D-3D S-doped CoZnNi-OH/CuCoP positive microelectrode with hierarchical structure on 1D metal fiber substrate for high-capacitance fibrous micro-SCs. Such unique architecture, which 2D S-doped CoZnNi-OH nanosheet arrays vertically aligned on 1D Cu wire garnished with 3D dendritic CuCoP through CoZn-MOF template, exposed ample electroactive sites, created robust electrical and mechanical joint between nanostructured material and metal fiber, and promote the transport/diffusion rate of ions. The achieved 2D-3D S-doped CoZnNi-OH/CuCoP/CW microelectrode exhibited the areal/volumetric/length capacitances of 2.9 F cm−2, 290.07 F cm−3, and 348 mF cm−1 at 4 mA cm−2, respectively, which is 18 times of the sulfide directly co-electrodeposited on 3D CuCoP foam without MOF template. Besides, negative microelectrode was prepared through electrochemical deposition of V2O5-PPy on 1D carbon fiber substrate decorated with rGO-nanocellulose (NC) hydrogel. The electrical double layer capacitance behavior combined with pseudocapacitive properties enhances charge storage performance of fibrous microelectrode in terms of specific capacitance, cycle stability and rate capability. The fabricated solid-state 2D-3D S-doped CoZnNi-OH/CuCoP/CW//V2O5-PPy/rGO-NC/CF micro-SC presents high areal energy density of 127.62 µWh cm−2 at a power density of 1.83 mW cm−2 and durability (93.7 % retention after 5000 cycles) with excellent mechanical flexibility. Giving the versatility of 1D carbon/metal fiber substrates, template-assisted 3D architecture, MOF-derived sulfide nanoarrays, and NC chemical reactivity, the proposed strategy can be used for construction of other next-generation miniaturized portable electronics.

Polymerized complex and electrodeposition synthesis of Ni-doped CuCo2O4 on flexible carbon fibers as a flexible electrocatalyst for oxygen evolution reaction

In this work, Ni-doped CuCo2O4 (Cu1–xNixCo2O4, x=0, 0.20, 0.40, 0.60 and 0.80) catalysts wer synthesized by polymerized complex and electrodeposition methods on flexible carbon fiber substrates for the oxygen evolution reaction (OER) in alkaline solution. The crystallinity and surface morphology of the catalysts were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM).The XRD results showed that the crystallinity corresponded to CuCo2O4 phases. The OER revealed that Cu0.40Ni0.60Co2O4 had higher activity for OER with a low overpotential of 256 mV at a current density of 10 mA cm–2, which was better than CuCo2O4 (451 mV). The results suggest that the presence of Ni2+ ions in spinel CuCo2O4 exhibited superior electrocatalytic activity towards OER with lower overpotential, and higher current density than CuCo2O4.

Janus resorcinol-formaldehyde-based membrane with opposite wettability for efficient separation of oil and water emulsion

A resorcinol-formaldehyde (RF)-based Janus membrane was fabricated by casting graphene oxide (GO)-dispersed RF solution on Janus-B side and Cu salt-RF solution on the opposite Janus-A side of an activated carbon fibre (ACF) substrate, and then subjecting the composite material to chemical vapor deposition to form a web of carbon nanofiber (CNF) on the Janus-A side. CNF imparted the super-hydrophobic (water contact angle WCA ∼151°) and super-oleophilic (oil contact angle OCA ∼0°) characteristics, while GO-RF imparted the hydrophilic (WCA 30°) and olephobic (OCA ∼121°) characteristics to the membrane. The microfiltration tests were carried out under different conditions of oil and water feed concentrations (0–15% v/v) and operating pressure (1–3 bar). The super-hydrophobic side showed 99.75% water rejection efficiency and the initial permeate flux of 1020 Lm−2h−1 for a 5% (v/v) water-in-oil (W/O) emulsion, while the hydrophilic side showed 99.96% oil rejection efficiency and the initial permeate flux of 380 Lm−2h−1 for 5% (v/v) oil-in-water (O/W) emulsion. The material showed good chemical stability in acidic, basic and corrosive media as well as an excellent repeatability under the repeated alternate cycles of pure diesel/water and emulsion post- simple ethanol wash. Considering that the method of fabrication is simple, fast, and scalable, the comparative performance data clearly pitch CNF-RF/ACF/GO-RF ahead of the other membranes discussed in the literature for oil-water emulsion.

Research on the Application of Domestic High-Modulus Carbon Fiber/Epoxy Composites to Solar Panels for Solar Arrays

Based on the new high-modulus carbon fiber CCM40J-6k, which is the critical raw material of a solar panel, the molding process of a mesh face sheet combined with epoxy resin, the overall mechanical performance of a mesh face sheet combined with aluminum honeycomb, the compatibility with polyimide insulation film + solar cell circuit, and the space environment adaptability must pass a test verification and assessment as the premise for large-scale orbit applications. Therefore, based on the traditional carbon fiber M40JB-6k as a reference, a systematic verification project was conducted to apply the CCM40J-6k carbon fiber composite at the process, component, and assembly levels. Six aspects of testing and verifying items were conducted, including mechanical properties under room temperature and thermal shock conditions, bonding force of mesh nodes, comparison of the adaptability of domestic and imported carbon fiber substrates to high–low temperature alternation, the ability of domestic carbon fiber substrates to adapt to the thermal environment after laying solar cell circuits, and in-orbit lifespan of solar panels. Based on the verification results, the mechanical properties of the substrate are the same as those of the imported M40JB-6k, and the actual molding process for M40JB-6k can be utilized. Sample pieces of the substrates can withstand the thermal shock and thermal cycling tests. The bending stiffness of the sample pieces before and after the tests is 3.5%~9.6% higher, and the bending strength is 4.2%~7.2% lower. The tensile strength of mesh nodes made of domestic carbon fiber is 18.9% higher than that of mesh nodes made of imported carbon fiber. The CCM40J-6k substrate is similar to triple-junction GaAs solar cells. The change rates of the open-circuit voltage and the short-circuit current of solar panels based on domestic carbon fiber after fatigue thermal cycling with 2070 cycles are 0.55% and 0.24%, respectively. The above results indicate that the comprehensive performance of the domestic carbon fiber CCM40J-6k meets the requirements and can be applied to solar panels for solar arrays.

Direct Integration of Perovskite Solar Cells with Carbon Fiber Substrates.

Integrating photovoltaic devices onto the surface of carbon-fiber-reinforced polymer substrates should create materials with high mechanical strength that are also able to generate electrical power. Such devices are anticipated to find ready applications as structural, energy-harvesting systems in both the automotive and aeronautical sectors. Here, the fabrication of triple-cation perovskite n-i-p solar cells onto the surface of planarized carbon-fiber-reinforced polymer substrates is demonstrated, with devices utilizing a transparent top ITO contact. These devices also contain a "wrinkled" SiO2 interlayer placed between the device and substrate that alleviates thermally induced cracking of the bottom ITO layer. Devices are found to have a maximum stabilized power conversion efficiency of 14.5% and a specific power (power per weight) of 21.4Wg-1 (without encapsulation), making them highly suitable for mobile power applications.

Flexible Carbon Fiber/TiO2 Nanopillars Electrode in the Detection of Glucose Under Photoexcitation

The development and utilization of biosensors have received a great attention from the scientific community due to their wide applications in the areas of food safety, medical diagnosis, environmental monitoring and other fields. In this paper, we report the development of a novel photoelectrochemical (PEC) sensor for glucose detection using a flexible carbon fiber/TiO2 nanopillars electrode. The carbon fiber/TiO2 nanopillars was prepared by two step process in which the first step is to grow TiO2 seeds over carbon fiber by magnetron sputtering while the second step leads the growth of TiO2 nanopillars over flexible carbon fibers substrate. Under photoexcitation, the PEC sensor showed a significant enhancement in the sensitivity for glucose detection. The detection mechanism was based on the photoelectrochemical oxidation of glucose to gluconic acid, which generated an electrical signal that was proportional to the glucose concentration. The electrochemical examinations were performed at low glucose concentrations in the range of 1–5 mM (mmol L−1) to investigate the corresponding photocurrent. The results showed that the photocurrent increases with increasing the glucose concentration. This is of great significance for the detection of hypoglycemia, and has good application prospects in the fields of nano-detection, biological diagnosis and wearable devices. The flexible carbon fiber/TiO2 PEC sensor developed in this study is a promising approach for the development of wearable devices for continuous glucose monitoring.

Electrostatic spray catalytic particle coating on carbon electrode for enhancing electrochemical reaction

The uniform coating of catalytic materials on the electrode surface is essential for improving the performance of electrochemical reactions. In this study, the electrostatic spray coating technique is used to deposit Molybdenum disulfide (MoS2) particles on carbon electrodes and examine the electrochemical hydrogen evolution reaction (HER) performance in a 0.1 M H2SO4 electrolyte. The experimental results reveal that the electrostatic spray coating method achieves a more uniform coating MoS2 catalyst particles on the carbon fiber substrate. It provides good adhesion for electrocatalyst binding on the carbon paper electrodes. During HER analysis, a 25% higher current density is obtained from the electrostatic spray-coated electrodes compared to the manual spray-coated electrode at a potential of 0.95 V. Electrochemical impedance spectroscopy, and electrochemical surface area measurements indicate the superior electrochemical characteristics of the electrostatic spray-coated electrode. The faradaic efficiency of the electrostatic spray-coated electrode is close to 100% at a high applied potential of −1.6 V with a 0.0059 L volume of hydrogen generation. Moreover, chronoamperometric measurements demonstrate the excellent durability of the electrostatic spray-coated carbon electrodes. This study suggests that the facile electrostatic spray method is efficient for coating electrodes with high uniformity and good adhesion for various electrochemical applications.

Freestanding wide layer spacing MoS2@WS2@CC ternary structure with fast diffusion path for a highly activity zinc-ion batteries

Water system zinc ion batteries (ZIBs) displays the attractive advantages and it has been considered as the main energy storage device to replace lithium ion batteries (LIBs). Unfortunately, the existing cathode materials are far from achieving the excellent performance required by increasing energy consumption. In recent years, the popular MoS2 materials still suffer from the inherent defects of poor electrical conductivity, unstable structure, and large volume expansion and lamellar stacking during charging and discharging, resulting in weak periodic stability and severely hindering its commercial applications. In view of the special requirements of cathode materials for ZIBs, this work innovatively proposes the construction of new-type ternary composite nanomaterials, comprehensively improve the practicability of MoS2 materials. The experimental results confirm that the prepared MoS2@WS2@CC composite material has high specific capacity and excellent rate performance, due to the synergistic effect of conductive carbon fiber substrate and large layer spacing WS2 which can improve the volume expansion and diffusion rate fundamentally. Therefore, we can predict that the MoS2@WS2@CC composite is expected to accelerate the commercial application of ZIBs, and provide ideas for the design of other energy storage materials.

Design study of outboard wing incorporating MFC for a morphing vehicle

A novel biomimetic morphing micro aerial vehicle was designed using macro fiber composites (MFCs) as control actuators. The vehicle features variable-sweep, multi-curved wings, and a tail, both of which were embedded with MFC bimorphs. The wing design has a span of 1.1 m unswept (wings fully extended) and 0.65 m swept, resembling falcons (Falco Peregrinus). A design study was conducted on the outboard wing’s MFC and carbon fiber substrate orientation to enhance the roll authority of the wings when fully extended. Finite element modeling, wind tunnel testing, and flight testing were conducted to model and optimize the design to obtain linear aerodynamic control with given MFC deflections. In addition, this research explores several configurations to increase roll authority of MFCs using segmented and overlapped sections resembling avian feathers. An overlapped wing configuration was discovered to have the potential to increase roll authority at the expense of adverse yaw. Flight testing proved that MFC-actuated, continuous outboard wings provide sufficient roll authority and handling quality without added compensation for the non-linear behavior of MFCs. This research showed that MFCs can be incorporated into a morphing wing design for manual flight and autonomous flight through feedback from inertial sensors onboard the vehicle.

Synthesis of spherical mullite/Yb2SiO5 composite EBC powder by using mechanical alloying and spray dry processes

Abstract Environmental barrier coatings (EBCs) have been widely used as protective layers to protect the surface of ceramic components from water vapor degradation and hot corrosion at operating temperature. In this study, ytterbium monosilicate (Yb2SiO5) and mullite (3Al2O3·2SiO2) powders were synthesized by mechanical alloying to be considered as a new environmental barrier coating. The composite powder was granulated by the spray dryer process and deposited on SiC reinforced by carbon fibers (SiC/Cf) substrate using the atmospheric plasma spray method. Phases in the synthesized composite powders and the deposited EBC were identified using X-ray diffraction. A field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy was utilized to study the powder morphology and coating microstructure. After the spray dry processing, the powders exhibited a spherical morphology and good-flowability with a mean particle size of 20–40 µm. The coating thickness was measured to be between 100 and 150 μm. In addition, the results of nanoindentation testing exhibited a hardness of about 8 GPa and an elastic modulus of about 111 GPa for the deposited coatings.

Hydrogen bond enforced polyaniline grown on activated carbon fibers substrate for wearable bracelet supercapacitor

The polyaniline grown on activated carbon fibers (PANI-ACF) was synthesized through an electrochemical deposition process to act as the energy storage electrode material for wearable bracelet supercapacitor application. The ACF was synthesized by activating carbon fibers through hydrothermal process in HNO3 solution and then thermal process in argon atmosphere, which kept the microporous surface structure and oxygen-containing functional groups. The ACF substrate could contributes to improving electrical conductivity and activation of PANI-ACF. The density functional theory calculation result shows that PANI-ACF has larger Fermi energy than PANI. The XPS spectrum measurements and Mulliken charge distribution analysis indicate the formation of interfacial hydrogen bond interaction between hydroxyl group of ACF and amino group of PANI in PANI-ACF. The HOMO-LUMO energy gap decreases from 2.62 eV of PANI to 0.23 eV of PANI-ACF, indicating the bonding interaction is beneficial to improve conductivity of PANI. The PANI-ACF achieves superior capacitance of 296.3 F g−1 at 1.0 A g−1 and maintains reasonable capacitance retention of 63.8 % when the current density increases from 1.0 to 10 A g−1. Electroactive PANI-ACF electrode was applied for wearable bracelet-supercapacitor, which exhibits the energy density of 30.42 Wh kg−1 at power density of 900 W kg−1. So, hydrogen bond enforced PANI-ACF electrode with high capacitance and flexibility properties presents the promising wearable energy storage application.

Experimental investigation on a combination of soil electrokinetic consolidation and remediation of drained water using composite nanofiber-based electrodes

A novel electrokinetic geosynthetic (EKG) can be efficient in achieving multiple objectives. In this study, a new EKG as an electrode and a drainage channel in the electro-osmotic consolidation was fabricated by electrospun nanofibers containing graphene nanoparticles (GNs) attached to a carbon fiber substrate. To investigate the effectiveness of the fabricated electrodes in electro-osmotic consolidation and remediation of water drained from the system, an experimental apparatus was constructed while considering loading capability in expanded ranges and applying the electric field, and was filled with copper (Cu)-contaminated kaolinite. Experiments were divided into control (CT) and EKG groups, and three categories, C-EK, ES1-EK, and ES2-EK (using carbon fiber, electrospun nanofibers containing 1 wt% GNs, and electrospun nanofibers consisting of 2 wt% GNs, respectively). All the experiments were conducted with the same conditions, loading, drainage condition, and duration. However, EKG experiments were performed by employing the electric field under the vertical pressure in the range of 7–113 kPa, while the CT was conducted without the electric field. According to experimental results, 18 wt% polymethyl methacrylate in the dimethylformamide solvent containing 1 and 2 wt% GNs was selected for making a nanofibrous layer on the carbon fiber. The average diameters of the fibers were 404 ± 36 and 690 ± 62 nm and yielded at 1 and 2 wt% GNs, respectively. The results revealed that using the EKG accelerated kaolinite consolidation. The average degree of consolidation was 68 and 85% in the CT and EKG experiments, respectively. Furthermore, the fabricated electrodes were highly effective as a drainage channel for remediating water drained from the system. Moreover, the highest Cu removal efficiency was obtained in ES2-EK (97%) and ES1-EK (92%), respectively. Conversely, the lowest Cu removal efficiency was observed in the C-EK group (85%).

Nanoscale geometry determines mechanical biocompatibility of vertically aligned nanofibers

Vertically aligned carbon nanofibers (VACNFs) are promising material candidates for neural biosensors due to their ability to detect neurotransmitters in physiological concentrations. However, the expected high rigidity of CNFs could induce mechanical mismatch with the brain tissue, eliciting formation of a glial scar around the electrode and thus loss of functionality. We have evaluated mechanical biocompatibility of VACNFs by growing nickel-catalyzed carbon nanofibers of different lengths and inter-fiber distances. Long nanofibers with large inter-fiber distance prevented maturation of focal adhesions, thus constraining cells from obtaining a highly spread morphology that is observed when astrocytes are being contacted with stiff materials commonly used in neural implants. A silicon nanopillar array with 500 nm inter-pillar distance was used to reveal that this inhibition of focal adhesion maturation occurs due to the surface nanoscale geometry, more precisely the inter-fiber distance. Live cell atomic force microscopy was used to confirm astrocytes being significantly softer on the long Ni-CNFs compared to other surfaces, including a soft gelatin hydrogel. We also observed hippocampal neurons to mature and form synaptic contacts when being cultured on both long and short carbon nanofibers, without having to use any adhesive proteins or a glial monoculture, indicating high cytocompatibility of the material also with neuronal population. In contrast, neurons cultured on a planar tetrahedral amorphous carbon sample showed immature neurites and indications of early-stage apoptosis. Our results demonstrate that mechanical biocompatibility of biomaterials is greatly affected by their nanoscale surface geometry, which provides means for controlling how the materials and their mechanical properties are perceived by the cells. Statement of significanceOur research article shows, how nanoscale surface geometry determines mechanical biocompatibility of apparently stiff materials. Specifically, astrocytes were prevented from obtaining highly spread morphology when their adhesion site maturation was inhibited, showing similar morphology on nominally stiff vertically aligned carbon fiber (VACNF) substrates as when being cultured on ultrasoft surfaces. Furthermore, hippocampal neurons matured well and formed synapses on these carbon nanofibers, indicating high biocompatibility of the materials. Interestingly, the same VACNF materials that were used in this study have earlier also been proven to be capable for electrophysiological recordings and sensing neurotransmitters at physiological concentrations with ultra-high sensitivity and selectivity, thus providing a platform for future neural probes or smart culturing surfaces with superior sensing performance and biocompatibility.

Preparation of carbon fiber substrates with structural colors based on photonic crystals

It is well-known that carbon fiber (CF) cannot be colored by traditional dyeing methods due to the strong inertness of fiber surface. With the increasing demand of consumers for fashion, colorful and diverse CF have attracted extensive attention. In this paper, inspired by the structural colors in nature, structural coloration of CF substrates by rapidly constructing photonic crystals (PCs) with structural colors was realized. The poly (styrene-methacrylic acid) (P(St-MAA)) colloidal microspheres prepared by a soap-free emulsion polymerization were used as building units to construct PCs. The influence of mass fraction of colloidal microspheres and the density of substrates on the structural colors of CF fabrics was investigated. The spraying method was also used to achieve structural color patterns on CF boards. Moreover, in order to improve the durability of structural colors, the resultant CF boards with structural colors were encapsulated with polydimethylsiloxane (PDMS). The results showed that according to Bragg diffraction law, P(St-MAA) colloidal microspheres with particle sizes of 213 nm, 235 nm, 255 nm and 307 nm can present PCs structural colors. When the mass fraction of the colloidal microspheres was 10%, brighter structural colors can be obtained on the CF fabrics with the higher density. The structural colors of patterns on the CF boards were bright and vivid. Furthermore, the colored CF boards encapsulated with PDMS could still maintain bright structural colors after rubbing and rinsing tests. The research will provide new approaches to ecological coloration of CF substrates.

A Pore‐Forming Strategy Toward Porous Carbon‐Based Substrates for High Performance Flexible Lithium Metal Full Batteries

Self‐standing carbon‐based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium (Li) metal batteries (FLMBs). Current strategies for modifying carbon materials are normally carried out on powder carbon, and very few of them are suitable for self‐standing carbon substrates. Herein, a pore‐forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode. Starting with cotton cloth, the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode (LMA). Simulations indicate that the porous structure leads to homogeneous ion flux, Li‐ion concentration, and electric field during Li deposition. Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV. Via a similar route, porous carbon cloth substrate is obtained for subsequently seeding V2O5 nanowires to prepare the cathode. The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of ~100% even under dramatic deformation. The demonstrated strategy has far‐reaching potential in preparing free‐standing porous carbon‐based materials for flexible energy storage devices.