Carbon Nanowires Research Articles

Active sites-enriched carbon matrix enables efficient triiodide reduction in dye-sensitized solar cells: An understanding of the active centers

Understanding the activity origins of electrocatalysts for the triiodide (I3-) reduction is highly desirable in dye-sensitized solar cells (DSSCs). Herein, we report a robust strategy to craft nitrogen-doped carbon nanowires (NCWs) through combining oxidation polymerization from p-phenylenediamine with carbonization process. Owing to the abundant edges of the graphite microcrystals embedded in the NCWs and the incorporated N species, the NCWs synthesized at 700 °C exhibit a superior response to the I3- reduction in DSSCs with a high power conversion efficiency of 8.90%, outperforming the Pt reference (8.09%), and a high stability is also manifested. Theoretical calculations reveal that, of various doped N species within NCWs, the quaternary N species can significantly decrease the ionization energy and modulate the spin density distribution of carbon frameworks, thus promoting the electron transfer from the external circuit to the electrolyte. Natural population analysis further reveals that the active centers within the NCWs for the I3- reduction are those positively charged carbon atoms adjacent to the quaternary N. As such, this work will pave an avenue for rational design and engineering of inexpensive yet high-efficiency carbon electrocatalysts for the advanced energy applications.

Reduced Graphene Oxide Nanostructures by Light: Going Beyond the Diffraction Limit

Graphene oxide (GO) offers excellent possibilities that are recently demonstrated in many applications ranging from biological sensors to optoelectronic devices. The process of thermal annealing aids in removing the oxygen-containing groups in GO, making GO more graphene-like, or the so-called reduced graphene oxide (rGO). Thermal reduction can also be achieved by intense light. Here, we demonstrate a scalable, inexpensive, and environmentally friendly method to pattern graphene oxide films beyond the diffraction limit of light using a conventional laser. We show that contrary to previous reports, non-linear effects that occur under high intensity conditions of laser irradiation allow the fabrication of highly conductive carbon nanowires with dimensions much smaller than the laser spot size. The potential of this method is illustrated by the fabrication of several devices on flexible and transparent substrates, including hybrid plasmonic/rGO sensors.

Cobalt nanoparticle-encapsulated carbon nanowire arrays: Enabling the fast redox reaction kinetics of lithium-sulfur batteries

The commercial application of lithium-sulfur batteries is still impeded by the unsatisfying cyclability due to the sluggish reaction kinetics and shuttling effect of polysulfide intermediates. We develop a cobalt nanoparticle-encapsulated carbon nanowire arrays on carbon cloth (CC@Co-CNAs) to enable the fast redox reaction kinetics of the lithium sulfur batteries. The nanowire array-decorated carbon cloth as conductive matrix for sulfur active material could provide highly exposed cobalt nanoparticle active sites, owing to the high length-diameter ratio of the prepared CC@Co-CNAs. The binding affinity between the cobalt nanoparticle-incorporated materials and polysulfide intermediates is enhanced by Co-S bonds, which facilitates the redox reaction of active materials and consequently results in a high sulfur utilization for cathode especially with high sulfur loading. The lithium sulfur battery with CC@Co-CNAs as electrode materials delivers a high initial discharge capacity of 1228 mAh g−1 at 0.25 C, and a high initial discharge capacity of 807 mAh g−1 at 1C with a low capacity fading rate of 0.06% per cycle during 300 cycles. Moreover, a discharge capacity of 958 mAhg−1 at 0.1 C is achieved for the cell even with a corresponding sulfur loading of 6.2 mg cm−2.

Molybdenum sulfide/nitrogen-doped carbon nanowire-based electrochemical sensor for hydrogen peroxide in living cells

Molybdenum sulfide nanosheets on nitrogen-doped carbon nanowires (MoS2/CN NWs) were utilized to construct an electrochemical biosensor for hydrogen peroxide (H2O2). Polypyrrole nanowires (PPy NWs) were synthesized using a surfactant-assisted method, and few layers of MoS2 nanosheet grew on PPy NWs by a hydrothermal approach. After a sintering process, the prepared MoS2/CN nanohybrid was supposed to enhance the electrochemical catalytic performance for H2O2 resulting from the synergistic effect between the high stability of CN NWs and abundant active sites of MoS2 nanosheets. The CN NWs served as the framework for the few-layered MoS2 to form a core-shell structure which could increase the stability and electrochemical conductivity of MoS2 nanocomposite. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the crystallinity of MoS2 and the nitrogen-doped carbon nanowires. The electrochemical responses showed that the MoS2/CN NWs modified electrode has a good catalytic performance toward H2O2 determination with a wide linear range from 2 to 500 μM, and a low detection limit of 0.73 μM (S/N = 3). Moreover, the fabricated electrochemical biosensor performed monitoring of H2O2 released from A549 living cells, indicating that the MoS2/CN NWs offered a simple and convenient pathway in the fields of electrochemical sensing.

Electrochemical supercapacitor performance of boron and nitrogen co-doped porous carbon nanowires

Boron and nitrogen co-doped carbon (BNDC) nanowires supporting on carbon paper substrate are designed as binder-free electrode material for supercapacitor application. Boric acid-polyaniline is synthesized via electro-polymerization route using polyvinyl pyrrolidone as a structure-directing agent, showing the close-packing nanowire structure. BNDC is then formed by simultaneously doping boron and nitrogen during carbonization process of boric acid-polyaniline, showing nanowire-interconnected network structure. BNDC exhibits high specific capacitance of 504.0 F g-1 at 1.0 A g−1 in 1.0 M H2SO4 electrolyte. The superior capacity performance results from the porous structure with high surface area of 1022.4 m2 g−1 and the pseudocapacitance of boron, nitrogen and oxygen-containing functional groups. BNDC shows the cycling capacitance retention of 97.4% after 10000 cycles at 10.0 A g−1, presenting good cycling stability. A symmetrical solid-state BNDC supercapacitor is constructed using BNDC electrode and polyvinyl alcohol-H2SO4 gel electrolyte. This device reveals specific capacitance of 255.7 F g-1 at 1.0 A g−1, energy density of 22.7 W h kg−1 at power density of 0.2 kW kg−1, the capacity retention of 91.0% after 5000 cycles at 5.0 A g−1 and an output voltage of 1.6 V. BNDC supercapacitor with comparable capacitance performance presents the promising application in electrochemical energy storage devices.

Morphology-directing transformation of carbon nanotubes under the irradiation of pulsed laser with different pulsed duration

Carbon nanowires have many interesting properties in electronic, opto-electronic and nanoelectromechanical devices due to their high aspect ratios. Carbon nanotubes are ideal templates for the synthesis of one-dimensional carbon nanowires. T-carbon nanowires have been recently produced by the pseudo-topotactic conversion of multi-walled carbon nanotubes (MWCNTs) under picosecond laser irradiation. There is no data about the relationship between the carbon product morphology and laser pulse duration reported so far. Pulsed laser induced reaction is a fast and far from equilibrium process. Carbon nanostructures with different morphology have been produced from carbon nanotube suspension in methanol under laser irradiation with different pulse duration. Carbon nanoparticles, porous carbon nanorods, and even diamond nanobundles have been obtained under nanosecond laser irradiation. The one-dimensional template growth from MWCNTs to carbon nanowires is not successful under nanosecond laser irradiation. However, different carbon nanowires with diameters similar to shortened carbon nanotubes have been easily produced from carbon nanotube suspension under the irradiation of picosecond and femtosecond pulsed laser. The morphology-directing transformations of carbon nanotubes have also explained using reported mechanisms.

Novel Organic Cathode for Li Based Battery Using Pillar[5]Quinone/Carbon/AgNWs

Rechargeable lithium based batteries have been widely used for portable devices such as cellular phone and laptop computer. Those electronics are more and more being multi-functionalized, and the energy storage devices for them are required much higher energy density. The energy storage system loading high energy density will also dominate the market of large scale power systems, in the rapid development of electric vehicles. Therefore, lithium ion battery with high specific capacity became an essential factor. Although the battery can offer a high gravimetric capacity of 3862 mAh g-1 by using lithium metal as the anode part, most of cathode materials which are represented as lithium (cobalt, nickel, manganese, aluminum) oxide are mainly restricted in capacity. Thus, the cathode is the most important aspect to offer the high capacity. Commonly used inorganic lithium metal oxide materials as the cathode part have drawbacks such as their low theoretical specific capacities (<170 mAh g-1), structure stability and their unstable trend of price. Also, the cathodic active materials have a disadvantage in that a high-temperature required for manufacturing process and the side reaction is not environmentally friendly. To overcome the disadvantages, the organic compounds have recently been considered as promising candidates for the next generation of energy storage systems. They have many obvious merit compared to the inorganic materials in high theoretical capacity (>400 mAh g−1), safety, sustainability, environmental friendliness and low cost. In addition, they are electroactive toward lithium metal as well as practically any metals like magnesium, zinc, aluminum owing to their redox electron reactions. Especially, Pillar[5]quinone (P5Q), containing five quinone units linked by methylene bridges at para positions, can not only implement a high theoretical capacity of 446 mAh g−1 but also realize so effective for the use of the active sites that it is able to favorable to Li ion uptake. However, those kinds of organic materials with small molecular weight have two critical problems. First, they are easy to dissolve in aprotic electrolyte such as carbonate-based solvent, leading to poor cyclability and rapid capacity fading. Second is that the low conductivity of organic molecules limits their rate performance. In the effort of solve the problems, we fabricated the cathode using the P5Q enveloped in carbon (e.g. MWCNTs and CMK-3) and silver nanowires (AgNWs) with simple vacuum filtration method. At first, P5Q was obtained after synthesizing 1,4-dimethoxypillar[5]arene and the products obtained by each step were identified by using 1H, 13C NMR and FT-IR spectra. Carbon and AgNWs act as a framework, allowing to trap the active material. Furthermore, they perform a current collector, providing the conductive pathway of electrons for fast charging/discharging the battery. It doesn’t need binders and aluminum foil which is components of traditional slurry type of cathode. As the result, not only constrains the solubility in organic electrolyte, preparing the electrode synthesized with P5Q/carbon/AgNWs nanocomposite gives the enhanced conductivity. The content of each components was verified by Thermogravimetry Analysis(TGA). Suggested cathode has super-lightweight and an extremely low resistance of 2~3 ohm cm. Also, it demonstrates a specific discharge capacity of about 420 mAh g−1 at 0.1C. and an average operation voltage of 2.8 V when applying Li metal battery. For obtaining a high specific initial capacity, ether-based solvents (1,3-dioxolane/dimethoxyethane=1:1) containing high concentration Li salt (Bis(trifluoromethane)sulfonimide lithium salt) were used instead of carbonate-based electrolytes, achieving the reversible cycles. Moreover, the electrolyte was optimized by adding LiNO3 additive, preventing the formation of a protective layer on the surface of Li anode as well as the dissolution of active material (P5Q) in the electrolyte with high Li salt concentration. Likewise, the proposed battery concept reveals a high possibility of future battery and novelty by optimizing the electrolyte and modifying the cathode. Those methods can be applied at other organic cathode for Li based battery to reach their theoretical capacity and improve the cycle performance.

A Highly Tunable Fabrication Process for Binder-Free Three-Dimensional Carbon Nanoarchitectures for Supercapacitor Electrode Via Nanotransfer Printing Technique

Among various energy storage systems, supercapacitors are known to be excellent candidates with inherent fast charge-discharge characteristics and outstanding cycle stability, but are known to be mediocre in the energy density aspect. In order to realize their full potential, the electrode nanostructure needs to be carefully designed and fabricated, maximizing the surface area for electrochemically active sites while maintaining the conductivity and stability. Here, we report a novel and straightforward fabrication method for a binder-free carbon nanoarchitecture that meets these conditions. Using a solvent-assisted nanotransfer printing technique, a three-dimensional nanoarchitecture is assembled with highly controllable and consistent pore sizes, applicable in both EDLC and pseudocapacitor electrodes. In this study, arrays of carbon nanowires were transfer-printed using polymer replicas of silicon substrates with linear trenches of various widths and periods, ranging from few hundred nanometers to micrometers. The printing process was repeated multiple times to assemble mesh-like carbon nanoarchitectures with desirable thicknesses. Due the simplicity of the process, the fabrication method is highly versatile, modifiable in numerous elements such as thickness and width of the carbon, pattern size, intersection angles, and so forth. The patterns were fabricated in a wide range of dimensions to investigate the effect of pattern sizes in the electrode performance. Such tunability enables comprehensive analysis of effect of the electrode pore size and structure in supercapacitor performance. The electrochemical performances of the electrodes were tested by manufacturing a series of supercapacitor on CR2032 coin cells. Two symmetric electrodes were isolated using an ion-porous separator and organic solvent was used as the electrolyte. All coin cell assembly was conducted in a dry room with relative humidity lower than 2% to prevent any contamination in the electrolyte. Furthermore, we report additional processes to widen the application capability of the described fabrication method. Hierarchical structures have been fabricated by printing alternating layers of patterns of different dimensions. Larger nanowires provide apertures that act as pathways for efficient access of electrolyte to the active material, while smaller nanowires contribute to increase the surface area. Moreover, this nanoarchitecture can be modified for pseudocapacitors or other energy storage applications. Metallic nanoparticles can be dispersed and embedded on the carbon surface to form carbon-metal or carbon-metal oxide composite materials, allowing the aforementioned advantages of this structure to be similarly applied in other devices. This three-dimensional nanoarchitecture fabrication process provides a highly tunable and straightforward method based on transfer-printing technique, and further investigations and optimizations can be expected from the high versatility. Figure 1

Electrochemical performance of polyaniline-derivated nitrogen-doped carbon nanowires

The binder-free all-carbonaceous-component electrode was constructed by directly growing electroactive materials of nitrogen-doped carbon (NDC) on the substrate material of carbon paper (CP). The nitrogen-enriched polyaniline could be converted into NDC nanowires to cover on the surface of CP through electro-polymerization and carbonization processes. The polyaniline-derivated NDC electroactive material exhibits high capacity of 404.0 F g−1 at 1.0 A g−1. The superior capacitance results from the good electron-donor properties of heterocyclic nitrogen distributed in the carbon skeleton and reversible redox reactivity of exocyclic nitrogen-containing functional groups at the edge of carbon skeleton. A low capacity decay of 22% indicates high rate capability when current density increases from 1.0 to 10 A g−1. A high capacity retention ratio of 95.8% after 5000 cycles at 10.0 A g−1 presents good cycling stability. A symmetrical solid-state supercapacitor was constructed using NDC/CP electrode and polyvinyl alcohol-H2SO4 gel electrolyte. The device delivers a specific capacitance of 187.1 F g−1 at 1.0 A g−1, an energy density of 66.54 Wh kg−1 at the power density of 0.8 kW kg−1, the capacity retention ratio of 94.1% after 5000 cycles at 5.0 A g−1 and an output voltage of 1.6 V, which is comparable to the reported state-of-the-art carbon-based supercapacitor. The all-carbonaceous-component electrode presents promising application in electrochemical energy storage devices.

Rational Design of Hierarchical MnO@N-doped Carbon Nanowires as a High-Performance Anode for Lithium-Ion Batteries

Rational Design of Hierarchical MnO@N-doped Carbon Nanowires as a High-Performance Anode for Lithium-Ion Batteries

Study on copper–fullerene nanocomposite irradiated by 120 MeV Au ions

We report the swift heavy ion irradiation induced tailoring of structural properties of nanocomposite thin films of copper nanoparticles embedded in fullerene matrix. Cu metal nanoparticles with low metal concentration (~ 5 at%) are deposited in fullerene C60 matrix. The thickness of the combined film is about 50 nm as revealed by Rutherford backscattering spectrometry. The absorbance of copper nanoparticles did not exhibit any characteristic plasmon resonance owing to low concentration of metal. The analysis of results of Raman spectroscopy demonstrated the structural transformation of fullerene to amorphous carbon at high fluence of 120 MeV Au ion beam. The formation of structures such as carbon nanowires as a result of irradiation has been revealed by FESEM micrographs. TEM results confirm the formation of small size copper nanoparticles in pristine film and growth of the Cu particles under the effect of swift heavy ions irradiation. I-V characteristics of metal-fullerene nanocomposite thin films give a clear indication that the value of resistance decreases due to effects of increasing fluence of ion irradiation.

Buckling behaviors of single-walled carbon nanotubes inserted with a linear carbon-atom chain

Buckling behaviors of single-walled carbon nanotubes (SWCNTs) inserted with a linear carbon-atom chain (CAC) (the composite structures are also called carbon nanowires (CNWs)) under torsion and bending as well as compression are studied using molecular dynamics (MD) simulations, respectively. Our MD results show that the critical buckling angles (or strains) of CNWs under the three presented kinds of loading patterns can be two times those of corresponding independent SWCNTs for long CNWs, while the buckling improvement is not obvious for short ones. The main reason is that the radial van der Waals force between the CAC and the SWCNT is very small for a short CNW, while it increases with increasing length and then tends to a constant for a long CNW. The obtained MD results agree well with those from available theoretical models. These findings will be a great help towards understanding the stability and reliability of the special CNT structures, and designing flexible CNT-based devices.

Enhanced electrocatalytic activity and durability of Pt nanoparticles supported on ordered bimodal mesoporous carbon nanowires

Ordered bimodal mesoporous carbon nanowires (OMCWs) is prepared from dual templates that were fabricated by filling silica nanospheres in the channels of porous anodic aluminum oxide (AAO) membranes. The prepared OMCWs material exhibits a large surface area (876.7 m2 g−1), ordered large mesoporous (30 nm) nanostructure and small mesopores on the large mesopore walls. Pt nanoparticles are deposited on OMCWs to form Pt/OMCWs electrocatalyst for methanol oxidation reaction (MOR). In Pt/OMCWs, Pt nanoparticles (∼1.8 nm) are uniformly located on the OMCWs. The Pt/OMCWs catalyst possesses larger electrochemically active surface area (ECSA) (93.3 m2 g−1), higher activity for MOR and better durability compared with the commercial Pt/C catalyst. The good electrochemical performance of Pt/OMCWs is ascribed to the unique bimodal mesoporous structure that could facilitate the rapid mass transfer and enhanced the dispersion of Pt nanoparticles and the one-dimensional structure that could enhance the electron transport.

Metal-organic framework derived Fe2O3 nanocubes on intertwined N-doped carbon nanowires for fiber-shaped supercapacitor

3D N-doped carbon nanowires (NCWs) supported Fe2O3 nanocubes as anode materials in supercapacitors were successfully synthesized from metal-organic frameworks (MOFs) on flexible carbon fibers (CFs). Originating from the synergistic effect of Fe2O3 and NCWs, this anode exhibited high specific capacitance of 12.4 mF cm−1/39.6 mF cm−3 at a scan rate of 10 mV s−1 with excellent flexible property. An asymmetric supercapacitor based on our Fe2O3/NCWs/CFs anode demonstrated an extended operating voltage window of 2 V and improved linear specific capacitance of 6.1 mF cm−1 at a scan rate of 10 mV s−1. This asymmetric supercapacitor also obtained goodflexibility and long-term stability with an energy density of 2.7 mWh cm−3. The high supercapacitor performance is attributed to the 3D N-doped carbon nanowires which bring higher conductivity.

Front Cover: One‐Step Synthesis of Multifunctional Zinc‐Iron‐Oxide Hybrid Carbon Nanowires by Chemical Fusion for Supercapacitors and Interfacial Water Marbles (ChemNanoMat 6/2018)

Front Cover: One‐Step Synthesis of Multifunctional Zinc‐Iron‐Oxide Hybrid Carbon Nanowires by Chemical Fusion for Supercapacitors and Interfacial Water Marbles (ChemNanoMat 6/2018)

Room-temperature pre-reduction of spinning solution for the synthesis of Na3V2(PO4)3/C nanofibers as high-performance cathode materials for Na-ion batteries

The continuous and uniform Na3V2(PO4)3/C nanofibers are successfully synthesized through room-temperature pre-reduction with oxalic acid assisting electrospinning method for the first time. With the reduction and chelation of oxalic acid in the spinning solution, the V5+ can be reduced to V3+, and the viscosity and conductivity of the solution are well modified, so that the precursor and the final product nanofibers have more uniform, surface-smooth morphologies without spindle-like protrusions. The sample shows the well-crystallized rhombohedral Na3V2(PO4)3 phase and excellent electrochemical performances. The initial discharge specific capacity of the sample at 0.05C reaches up to 114.0 mAh g−1 and still remains 78.1 mAh g−1 at 10C rate. The capacity retention after 100 cycles at 0.05C still holds 97.0%, and the coulombic efficiency is always close to 100%. The causes that the Na3V2(PO4)3/C nanofibers exhibit good rate performances, cyclic ability and structural reversibility can be mostly ascribed to the perfect nanofibers. The uniform and smooth Na3V2(PO4)3/C nanofiber consists of Na3V2(PO4)3/C nanoparticles uniformly embed in the perfect 1D carbon nanowire, which builds up a continuous network with highly efficient electronic and ionic channels, thus the impressive properties can be realized.

Hierarchical Carbon-Silicon Nanowire Heterostructures for Hydrogen Evolution Reaction

Silicon nanowires (SiNWs) opened up exciting possibilities in a variety of research fields due to their unique anisotropic morphologies, facile tuning capabilities, and accessible fabrication methods. The SiNW-based photoelectrochemical (PEC) conversion has recently been known to provide an efficiency superior to various photo-responsive semiconductor heterostructures. However, a challenge still remains in designing optimum structures to minimize photo-oxidation and photo-corrosion of Si surface in a liquid electrolyte. Here, we synthesized hierarchically branched carbon nanowires (CNWs) on SiNWs utilizing copper vapors as catalysts in a chemical vapor deposition (CVD) process, which exhibit outperforming photocatalytic activities for hydrogen generation along with excellent chemical stability against oxidation and corrosion. First, SiNWs were prepared by a metal catalyzed electroless etching method and placed at the center of a quartz reactor in a CVD chamber. Next, a Cu foil was placed above the SiNWs without a physical contact, where Cu vapors from the foil catalyzes the growth of CNWs on SiNWs while flowing 50 sccm H2 and 15 sccm CH­4 for 10~40 min at 1,000 ˚C in an ambient pressure. Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), Selected Area Electron Diffraction (SAED), Raman spectroscopy, X-ray Photoemission Spectroscopy (XPS) analysis were employed to characterize the CNWs on the SiNWs, indicating that CNWs with various shapes and diameters are successfully grown on a SiNW. The PEC performance for the hydrogen evolution reaction shows that the catalytic activity is substantially dependent on the surface morphology of the CNWs-SiNWs. The applied bias photon-to-current efficiency (ABPE) in the optimized CNWs-SiNWs structure (1.86%) exhibits a higher value than in any of the other steps, which is also comparable to other carbon-based catalysts on the Si photocathode reported to date. Enhanced photocatalytic performance is substantially affected by the intrinsic wettability of the surface due to the polarization of electrochemical reaction. The long-term stability of the CNWs-SiNWs photocathode was tested for 300 cycles or for 11 hrs at a pH 0, showing a stable current density. The PEC performance of the Si cell is known to degrade easily due to surface oxidation in aqueous solutions, but our stability testing result implies that the CNWs efficiently suppress the degradation of photoelectrochemical performance by protecting Si surface from oxidation. In conclusion, various spectroscopic analyses revealed that the CNWs-SiNWs simultaneously played a key role in both as catalysts and electrodes, providing a new strategy to develop a new type of metal-free carbon-based structures with enhanced stability and catalytic reactivity essential for the higher performance of hydrogen evolution reaction. Thus, we believe that the CNWs-SiNWs photoelectrodes would provide a new route to develop high-performing cost-effective catalysts essential for advanced energy conversion and storage technologies.

One‐Step Synthesis of Multifunctional Zinc‐Iron‐Oxide Hybrid Carbon Nanowires by Chemical Fusion for Supercapacitors and Interfacial Water Marbles

AbstractHybrid carbon nanowires with tunable elemental composition and nanoscale component mixing resolution can be synthesized by a chemical fusion method in one pot, using a unique heating mechanism of conducting polymers under the electromagnetic field of microwave. Carbon nanowire matrices hybridized with metals and oxides can be facilely synthesized by simple instrumentation and processes within tens of seconds. Different metallic precursors (e. g. Fe and Zn) can be selectively incorporated in the chemical fusion process that substantially integrated with the carbon nanowire matrices during the growth process while their characteristic functions are infused. The hybrid carbon nanowires show excellent electrochemical supercapacitive and supramolecular self‐assembly properties owing to the unique hybrid nanostructures and surface characteristics. “Interfacial water marbles” can be obtained by the supramolecular self‐assembly of hybrid carbon nanowires on the water/hexane interface. The interfacial water marbles are semi‐permanent and completely impede the event of coalescence cascade, demonstrating significant applications in mass transport, microfluidics, and interfacial synthesis.

Thylakoid-Deposited Micro-Pillar Electrodes for Enhanced Direct Extraction of Photosynthetic Electrons.

Photosynthesis converts solar energy to electricity in a highly efficient manner. Since only water is needed as fuel for energy conversion, this highly efficient energy conversion process has been rigorously investigated. In particular, photosynthetic apparatus, such as photosystem II (PSII), photosystem I (PSI), or thylakoids, have been isolated from various plants to construct bio-hybrid anodes. Although PSII or PSI decorated anodes have shown potentials, there still remain challenges, such as poor stability of PSII-based systems or need for electron donors other than water molecules of PSI-based systems. Thylakoid membranes are relatively stable after isolation and they contain all the necessary photosynthetic apparatus including the PSII and PSI. To increase electrical connections between thylakoids and anodes, nanomaterials such as carbon nanotubes, nanowires, nanoparticles, or graphene have been employed. However, since they rely on the secondary electrical connections between thylakoids and anodes; it is desired to achieve larger direct contacts between them. Here, we aimed to develop micro-pillar (MP) array anodes to maximize direct contact with thylakoids. The thylakoid morphology was analyzed and the MP array was designed to maximize direct contact with thylakoids. The performance of MP anodes and a photosynthetic fuel cell based on MP electrodes was demonstrated and analyzed.

A high energy and power sodium-ion hybrid capacitor based on nitrogen-doped hollow carbon nanowires anode

The sodium ion hybrid capacitor (SHC) has been attracting much attention. However, the SHC's power density is significantly confined to a low level due to the sluggish ion diffusion in the anode. Herein, we propose to use an electrode with a high double layer capacitance as the anode in the SHC instead of insertion anodes. To this aim, nitrogen doped hollow carbon nanowires (N-HCNWs) with a high specific surface area are prepared, and the high capacitive contribution during the sodium ion storage process is confirmed by a series of electrochemical measurements. A new SHC consisting of a N-HCNW anode and a commercial active carbon (AC) cathode is fabricated for the first time. Due to the hybrid charge storage mechanism combining ion insertion and capacitive process, the as-fabricated SHC strikes a balance between the energy density and power density, a energy density of 108 Wh kg−1 and a power density of 9 kW kg−1 can be achieved, which overwhelms the electrochemical performances of most reported AC-based SHCs.