Hybrid Nanostructure Electrode Research Articles

Nanostructuring Strategies for Silicon‐based Anodes in Lithium‐ion Batteries: Tuning Areal Silicon Loading, SEI Formation/Irreversible Capacity Loss, Rate Capability Retention and Electrode Durability

AbstractInvited for this month's cover picture is the group of Prof. Dr. Costel‐Sorin Cojocaru. The cover picture illustrates the hierarchical hybrid nanostructured electrode composed of vertically aligned carbon nanotubes decorated with silicon nanoparticles as anode for next generation lithium‐ion batteries. Read the full text of the Research Article at 10.1002/batt.202200451.

Front Cover: Nanostructuring Strategies for Silicon‐based Anodes in Lithium‐ion Batteries: Tuning Areal Silicon Loading, SEI Formation/Irreversible Capacity Loss, Rate Capability Retention and Electrode Durability (Batteries & Supercaps 3/2023)

Graphical Abstract The Front Cover illustrates the hierarchical hybrid nanostructured electrode composed of vertically aligned carbon nanotubes decorated with silicon nanoparticles as anode for the next generation lithium-ion batteries. More information can be found in the Research Article by C.-S. Cojocaru and co-workers.

Nanostructuring Strategies for Silicon‐based Anodes in Lithium‐ion Batteries: Tuning Areal Silicon Loading, SEI Formation/Irreversible Capacity Loss, Rate Capability Retention and Electrode Durability

AbstractSilicon is one of the most promising anode materials for lithium‐ion batteries. Silicon endures volume changes upon cycling, which leads to subsequent pulverization and capacity fading. These drawbacks lead to a poor lifespan and hamper the commercialization of silicon anodes. In this work, a hybrid nanostructured anode based on silicon nanoparticles (SiNPs) anchored on vertically aligned carbon nanotubes (VACNTs) with defined spacing to accommodate volumetric changes is synthesized on commercial macroscopic current collector. Achieving electrodes with good stability and excellent electrochemical properties remain a challenge. Therefore, we herein tune the active silicon areal loading either through the modulation of the SiNPs volume by changing the silicon deposition time at a fixed VACNTs carpet length or through the variation of the VACNT length at a fixed SiNPs volume. The low areal loading of SiNPs improves capacity stability during cycling but triggers large irreversible capacity losses due to the formation of the solid electrolyte interphase (SEI) layer. By contrast, higher areal loading electrode reduces the quantity of the SEI formed, but negatively impacts the capacity stability of the electrode during the subsequent cycles. A higher gravimetric capacity and higher areal loading mass of silicon is achieved via an increase of VACNTs carpet length without compromising cycling stability. This hybrid nanostructured electrode shows an excellent stability with reversible capacity of 1330 mAh g−1 after 2000 cycles.

Anodic SnO2 Nanoporous Structure Decorated with Cu2O Nanoparticles for Sensitive Detection of Creatinine: Experimental and DFT Study.

Advanced anodic SnO2 nanoporous structures decorated with Cu2O nanoparticles (NPs) were employed for creatinine detection. Anodization of electropolished Sn sheets in 0.3 M aqueous oxalic acid electrolyte under continuous stirring produced complete open top, crack-free, and smooth SnO2 nanoporous structures. Structural analyses confirm the high purity of rutile SnO2 with successful functionalization of Cu2O NPs. Morphological studies revealed the formation of self-organized and highly-ordered SnO2 nanopores, homogeneously decorated with Cu2O NPs. The average diameter of nanopores is ∼35 nm, while the average Cu2O particle size is ∼23 nm. Density functional theory results showed that SnO2@Cu2O hybrid nanostructures are energetically favorable for creatinine detection. The hybrid nanostructure electrode exhibited an ultra-high sensitivity of around 24343 μA mM-1 cm-2 with an extremely lower detection limit of ∼0.0023 μM, a fast response time (less than 2 s), and wide linear detection ranges of 2.5-45 μM and 100 μM to 15 mM toward creatinine. This is ascribed to the creation of highly active surface sites as a result of Cu2O NP functionalization, SnO2 band gap diminution, and the formation of heterojunction and Cu(1)/Cu(ll)-creatinine complexes through secondary amines which occur in the creatinine structure. The real-time analysis of creatinine in blood serum by the fabricated electrode evinces the practicability and accuracy of the biosensor with reference to the commercially existing creatinine sensor. The proposed biosensor demonstrated excellent stability, reproducibility, and selectivity, which reflects that the SnO2@Cu2O nanostructure is a promising candidate for the non-enzymatic detection of creatinine.

Electrochemical Determination of Nandrolone as a Doping Agent in Sport by Molecularly Imprinted Polymers and Au Nanoparticles Hybrid Nanostructured Electrode in Biological Fluids

Electrochemical Determination of Nandrolone as a Doping Agent in Sport by Molecularly Imprinted Polymers and Au Nanoparticles Hybrid Nanostructured Electrode in Biological Fluids

Voltage-Switchable Biosensor with Gold Nanoparticles on TiO2 Nanotubes Decorated with CdS Quantum Dots for the Detection of Cholesterol and H2O2.

A thin layer of gold nanoparticles (Au NPs) sputtered on cadmium sulfide quantum dots (CdS QDs) decorated anodic titanium dioxide nanotubes (TNTs) (Au/CdS QDs/TNTs) was fabricated and explored for the nonenzymatic detection of cholesterol and hydrogen peroxide (H2O2). Morphological studies of the sensor revealed the formation of uniform nanotubes decorated with a homogeneously dispersed CdS QDs and Au NPs layer. The electrochemical measurements showed an enhanced electrocatalytic performance with a fast electron transfer (∼2 s) between the redox centers of each analyte and electrode surface. The hybrid nanostructure (Au/CdS QDs/TNTs) electrode exhibited about a 6-fold increase in sensitivity for both cholesterol (10,790 μA mM-1 cm-2) and H2O2 (78,833 μA mM-1 cm-2) in analyses compared to the pristine samples. The hybrid electrode utilized different operational potentials for both analytes, which may lead to a voltage-switchable dual-analyte biosensor with a higher selectivity. The biosensor also demonstrated a good reproducibility, thermal stability, and increased shelf life. In addition, the clinical significance of the biosensor was tested for cholesterol and H2O2 in real blood samples, which showed maximum relative standard deviations of 1.8 and 2.3%, respectively. These results indicate that a Au/CdS QDs/TNTs-based hybrid nanostructure is a promising choice for an enzyme-free biosensor due to its suitable band gap alignment and higher electrocatalytic activities.

Performance of hybrid SnO2/Li2FeMn3O8 nanostructured electrode for efficient Li ion storage application

Li2FeMn3O8 (LFMO) nanocomposite material for Li-ion battery is synthesized using chemical combustion method. To fabricate a hybrid nanostructure electrode, LFMO is coated on tin oxide (SnO2) nanorods (NR), which is grown using a vapor-liquid solid (VLS) technique on a steel substrate. The surface morphology of the hybrid nanostructure electrode confirms that, single crystalline SnO2 nanorods are grown vertically with spine-like structures, a few microns in length, as evident from field emission scanning electron microscope image. The electrochemical performance of SnO2/LFMO shows very interesting characteristic with enormous charge storage capability. The coin cell shows improved capacity with a higher number of charging and discharging cycles. This SnO2/LFMO hybrid composite electrode shows better specific capacitance value as compared to the pristine SnO2 electrode.

Three-dimensional Ni/MnO2 nanocylinder array with high capacitance for supercapacitors

Abstract Though high-capacitance transition metal oxides are considered as promising pseudocapacitive materials to achieve high-energy storage for supercapacitors, the practical capacitance is far from the theoretical values because of their intrinsic poor abilities about the electronic and ionic transports. Here, to tackle these problems, we develop a hybrid nanostructured electrode in a facile process, in which layer-structured δ-MnO2 nanosheets are anchored onto seamless three-dimensional Ni nanocylinder arrays. The resultant Ni/δ-MnO2 nanocylinder arrays exhibit high specific capacitance up to 883.2 Fg−1 at a scan rate of 10 mVs−1 and achieve high energy density about 108 Whkg−1 at a power of 2.4 kWkg−1. The improved electrochemical performance mainly benefits from the vertically aligned Ni/δ-MnO2 hybrid structure. Owing to such a hybrid structure the ion/electron transports are facilitated along the nanocylinders due to the reduction in the transport distance, and large accessible surface area is also provided for anchoring more high-capacitance materials. Moreover, the additional contact resistance can be dramatically reduced owing to the large interplanar spacing of δ-MnO2 and ordered semicoherent interface of Ni/δ-MnO2.

Surface functionalization of wafer-scale two-dimensional WO3 nanofilms by NM electrodeposition (NM = Ag, Pt, Pd) for electrochemical H2O2 reduction improvement

Surface functionalization of two-dimensional (2D) WO3 nanofilms by noble metal (NM) nanoparticles (NM = Ag, Pt and Pd) was successfully achieved for the first time via combination of the atomic layer deposition (ALD) process and electrochemical deposition method. Deposited NM nanoparticles were uniformly in the particle size and homogeneously dispersed on the surface of 2D WO3. They represented electrochemically active metal-semiconductor hybrid nanocomposites with the larger electroactive area, and consequently, substantially enhanced the electrochemical H2O2 detection of the device based on functionalized 2D WO3 nanofilms. Functionalization by Ag was found to be more efficient compared to the same functionalization by Pt and Pd nanoparticles. Particularly, Ag200-WO3 nanofilms exhibited the best electrochemical performance with a high sensitivity of 282 μA mM cm−2, extremely wide linear H2O2 concentrations range from 0.2 μM to 33.6 mM, a low detection limit of 0.1 μM, fast response time of 2 s and an excellent selectivity and long-term stability. Surface functionalization by NM nanoparticles approach has clearly demonstrated the great potential in the development of hybrid nanostructured electrode for various devices with enhanced electrochemical capabilities.

Pulsed Electrodeposition of Co3 O4 Nanocrystals on One-Dimensional ZnO Scaffolds for Enhanced Electrochemical Water Oxidation.

Pulsed electrodeposition has been introduced to deposit ultrathin flakes of Co3 O4 nanocrystals on ZnO nanorods. By fixing the seeding process, the scaffolding function of ZnO nanorods was studied by varying deposition times (30 s, 60 s, and 90 s) of Co3 O4 at a nucleation current of -1.0 mA cm-2 . The amount of deposited Co3 O4 has a strong influence on the oxygen evolution performance with ZnO scaffolds. To deliver a current density of 10.0 mA cm-2 in neutral solutions (0.5 M K2 SO4 ), the presence of ZnO scaffold electrodes negatively shifted the overpotential by ∼200 mV. In particular, the Co3 O4 /ZnO hybrid nanostructured electrode (60 s) exhibits the lowest onset potential of 1.5 V (vs. reversible hydrogen electrode, RHE). Electrochemical impedance spectra and double layer capacitance showed that the enhanced oxygen evolution activities originated from the improved charge transfer capability and the increased electrochemically active interface between Co3 O4 and ZnO.

Polyoxometalate Heterogeneous Nanostructures As Cathodes for Mg2+ Ion Storage

As global energy demands continue to rise each year, current state-of-the-art Li-ion battery (LIB) systems are predicted to reach the limit in the amount of energy that they can supply. In addition to this, LIBs are also limited by the low resource availability of Li metal. One proposed solution is to move away from LIBs to multivalent ion systems; of these alternatives, magnesium (Mg) is considered a promising material for the next generation of rechargeable batteries. Unlike Li, Mg metal does not form dendritic structures during cycling which would allow it to be employed as an anode which has a specific capacity of 2205 mAh/g compared to 777 mAh/g of the graphite anode that is currently used in LIBs. Mg also has a very high elemental abundance in the earth’s crust (2.44x104 ppm) which would drive down the production cost while simultaneously ensuring the longevity of these batteries in terms resource availability. Most importantly, the divalent nature of the Mg-ion means that it can carry twice the amount of charge per ion compared to Li. This is largely related to the high volumetric capacity (3833 mAh/ml) of Mg which is superior to even that of Li metal. While there is potential for Mg to replace LIBs, commercialization of these batteries has been hindered by sluggish insertion kinetics into cathode host materials as a direct result of the strong coulombic interactions experienced by the divalent Mg-ion. Due to this drawback, conventional metal oxide or sulfide insertion cathodes for Mg batteries tend to exhibit low capacities and operating voltages. In response to this, a large portion of Mg battery research is currently focused on the development of novel materials capable of functioning as cathodes for fast and efficient Mg-ion insertion. The idea proposed in this work is to depart from the conventional intercalation mechanism of LIBs and move towards a molecular cluster battery (MCB) based on polyoxometalate (POM) metal oxygen cluster molecules of early transition metals (Mo, W, V, or Nb). The unique redox activity of POMs are due to their intrinsic ability to form highly stable reduced and oxidized species allowing them to partake in fast reversible electron transfer reactions. Although POMs are also able to function as electron reservoirs, POMs themselves have negligible electronic conductivity as well as high solubility in both aqueous and organic media. Therefore, in order for these materials to be used as electrodes for electrochemical energy storage, they must first undergo hybridization with highly conductive insoluble substrates such as conductive organic polymers (COPs) or multi-walled carbon nanotubes (MWCNTs). The fabrication of heterogenous cathodes provide a “wiring” effect by electrically connecting the POM molecules allowing them all to take part in the redox chemistry while simultaneously anchoring them to a substrate, thus preventing any loss of active material to electrolyte dissolution during cycling. By taking advantage of the synergistic effect of pairing the ionically conductive POM molecule with the electrically conductive substrate; the resulting cathode material will thus be capable of fast electron transfer reactions with high ionic mobility. In this work, hybrid nanostructured electrodes of poly-3,4-ethylenedioxythiophene (PEDOT) and a phosphomolybdic acid (H3PMo12O40) POM have been fabricated electrochemically and applied as cathodes for Mg-ion storage. Preliminary cyclic voltammetry and galvanostatic cycling data have demonstrated an enhancement in the capacity of the PEDOT cathode after integration of the POM molecules throughout the polymer matrix. The initial cycling studies have also shown that the PEDOT-POM redox peaks are still present after 7 days of soaking in the organic electrolyte which suggests that the POM molecules do not readily dissolve out of the PEDOT matrix. This work highlights the potential of redox active POM inorganic clusters to function as cathodes with the capability of advancing the current state of Mg batteries.

Gold Nanoparticles Assembled Chemically Functionalized Reduced Graphene Oxide Supported Electrochemical Immunosensor for Ultra-Sensitive Prostate Cancer Detection

An ultra-sensitive electrochemical immunosensor was successfully developed to accurately detect prostate specific antigen. To improve the performance of immunosensor, it was fabricated by using hybrid nano-structured electrodes of high performance chemically functionalized reduced graphene oxide (CRGO) and gold nanoparticles (AuNPs) followed by covalently immobilized monoclonal anti-PSA antibody. We optimized the immunosensor, under different conditions using cyclic voltammetry and differential pulse voltammetry. We obtained a low detection limit of 3 pg mL−1 and wide linear range from 6 pg mL−1 to 30 ng mL−1, good reproducibility, selectivity, and stability. Finally, human serum samples were analyzed. The obtained recovery range was from 97% to 110% with relative standard deviation (RSD) of 3.88%. Thus, the developed immunosensor can provide a great potential in clinical and diagnostic applications.

Synthesis of three-dimensional hollow SnO2@PPy nanotube arrays via template-assisted method and chemical vapor-phase polymerization as high performance anodes for lithium-ion batteries

A novel polypyrrole (PPy) coated three-dimensional (3D) SnO2 nanotube arrays (SnO2@PPy) is synthesized via a template-assisted method followed by a chemical vapor-phase polymerization process as a high performance anode for lithium-ion batteries. In this new type electrode material, the hollow interiors of SnO2 are able to provide enough spaces for the accommodation of large volume expansion during the insertion of lithium-ion, making for the improvement of the stability of electrode. Meanwhile, the addition of conductive PPy layer could facilitate the electron transport, prevent the aggregation of active materials and warrant the stability of as-formed solid electrolyte interface (SEI) films. As a result, the integration of 3D hybrid nanostructure electrode is capable of retaining a high capacity of 646mAhg−1 after 150 cycles with a coulomb efficiency above 98% and a capacity retention of 221mAhg−1 even at a high current density of 5000mAg−1, revealing better cycling and rate properties compared with bare SnO2 nanotube arrays anode. This nanoengineering strategy can provide a facile and controllable way to synthesize other anode materials for lithium-ion batteries.

Nanoengineered three-dimensional hybrid Fe2O3@PPy nanotube arrays with enhanced electrochemical performances as lithium–ion anodes

In order to optimize the electrode system of lithium–ion batteries (LIBs) for problems like lithium-ion diffusion, electron transport, and large volume change during cycling processes, a novel three-dimensional (3D) hybrid Fe2O3 nanotube array anode coated by polypyrrole (Fe2O3@PPy) is synthesized via a sacrificial template-accelerated hydrolysis method followed by a chemical vapor-phase polymerization process. In the hollow core–shell nanostructures, the conducting PPy layer could not only facilitate the electron transport, but also force the core to expand inward into the hollow space, which allows for free volume expansion of the Fe2O3 without mechanical breaking. Besides, the static outer surface is contributed to form a stable solid electrolyte interface film. As a result, the integration of 3D hybrid nanostructure electrode is capable of retaining a high capacity of 665 mA h g−1 after 150 cycles with a coulombic efficiency of above 97 %, revealing better cycling properties compared with bare Fe2O3 nanotube arrays’ anode. This nanoengineering strategy is proven to be an ideal candidate for the development of high-performance anode for LIBs.

Nanocrystal-constructed mesoporous CoFe₂O₄ nanowire arrays aligned on flexible carbon fabric as integrated anodes with enhanced lithium storage properties.

A novel and facile two-step strategy is successfully developed for the large-scale fabrication of hierarchical mesoporous CoFe2O4 nanowire arrays (NWAs) on flexible carbon fabric as integrated anodes for highly efficient and reversible lithium storage. The synthesis involves the co-deposition of uniform bimetallic (Co, Fe) carbonate hydroxide hydrate precursor NWAs on carbon fabric and subsequent thermal transformation to spinel CoFe2O4 without damaging the morphology. The as-prepared CoFe2O4 nanowires have unique mesoporous structures, which are constructed by many interconnected nanocrystals with sizes of about 15-20 nm. The typical size of the nanowires is in the range of 70-100 nm in width and up to several micrometers in length. Such a hybrid nanostructure electrode presented here not only simplifies electrode processing, but also promises fast electron transport/collection and ion diffusion, and withstands volume variation upon prolonged charge/discharge cycling. As a result, the binder-free CoFe2O4/carbon fabric composite exhibits a high reversible capacity of 1185.75 mA h g(-1) at a current density of 200 mA g(-1), and a superior rate capability. More importantly, a reversible capacity as high as ∼950 mA h g(-1) can be retained and there is no obvious decay after 150 cycles.

Graphene-Based Hybrid Nanostructured Electrodes for Li-Ion Batteries

With the ever-increasing demand for energy storage, lithium ion battery has been an attractive technology that has revolutionized the portable electronic industry [1]. With its large scale applications, such as in hybrid electric vehicles (HEV’s), and plug-in HEVs, there is great interest in developing multifunctional hybrid nanostructured electrode materials for high performance Li-ion batteries [2,3]. Novel architectures of hybrid nanomaterials as both electrodes and electrolytes, have been shown to improve the device performances. New electrode materials with high electrical conductivity and large surface area, resulting in improved electrochemical performances are highly desirable. Though metal oxides with high specific capacity have been extensively studied as advanced Li-ion battery anodes, their structural instability under lithium insertion has been of great concern [4]. Hence, several approaches have been undertaken to improve the electrochemical performance of metal oxides as efficient Li-ion battery anodes. One of the strategies to increase the conductivity is by incorporating the anode material on the conducting carbonaceous matrix including mesoporous carbon, amorphous carbon, carbon nanotubes and graphenes [5].Here, we report the synthesis of Nb2O5 and TiNb2O7 -anchored graphene hybrid nanocomposites through simple hydrothermal method and its electrochemical performance studies as advanced anodes for lithium ion battery. The nanocomposite electrodes have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Thermo Gravimetric Analysis (TGA). Using these hybrid nanostructures as positive electrodes in 1 M LiPF6–EC/DMC electrolyte vs. Li metal negative electrodes, Cyclic voltammetry and Galvanostatic charge-discharge cycling measurements have been performed.The self-supported nanostructured electrodes, with graphene as support with homogenously anchored orthorhombic Nb2O5 (T-Nb2O5) and monoclinic TiNb2O7 nanoparticles, exhibited excellent electrochemical performance with high reversible capacity and enhanced rate capability, arising from the synergistic effect of Nb2O5 nanocrystals anchored onto conducting graphene layers. While the presence of three-dimensional structure in Nb2O5 and TiNb2O7 provides open channels and vacant sites for lithium intercalation, presence of conducting graphene sheets improve the kinetics of lithium ion and electron transport, leading to improved battery performances. The hybrid nanocomposite electrodes showed exceptional power capability, with ~80% of the total capacity sustained at 16C rate (Figure 2). We believe these hybrid nanocomposites, with superior electrochemical performance, can be used as efficient anode for high performance lithium ion battery. Figure 1. SEM images of (a) Nb2O5 nanocrystals (b) Nb2O5/graphene (c) TiNb2O7 and (d) TiNb2O7/graphene nanocompositeFigure 2. (a) Galvanostatic cycling of TiNb2O7/graphene nanocomposite electrode, (b) Rate capability of Nb2O5/graphene nanocomposite electrode. References J.-M. Tarascon and M Armand, Nature. 414, 359, (2001).P. G. Bruce, B. Scrosati and J.-M. Tarascon, Angew. Chem. Int. Ed. 47, 2930 (2008)A.L.M. Reddy, S. Gowda, M.M. Shaijumon and P.M. Ajayan, Adv. Mater. 24, 5045-5064 (2012)P. Poizot , S. Laruelle , S. Grugeon , L. Dupont , J.-M. Tarascon , Nature, 407, 496 (2000).Z.-S. Wu, W. Ren, L. Xu, F. Li, H.-M. Cheng, ACS Nano 5, 5463-5471 (2011)

Three-dimensional MnO2 nanowire/ZnO nanorod arrays hybrid nanostructure for high-performance and flexible supercapacitor electrode

Pure MnO2 nanowires and MnO2 nanowire/ZnO nanorod array hybrid nanostructure grown on carbon cloth are synthesized through a low temperature solution method for flexible and high performance supercapacitor applications. The MnO2 nanowire/ZnO nanorod hybrid nanostructured electrodes exhibit more than two times higher specific capacitance, and better capacitance retention than those of pure MnO2 nanowire electrodes. For the three-dimensional MnO2 nanowire/ZnO nanorod array hybrid electrode, a high specific capacitance of 746.7 F g−1 (areal capacitance ∼41.5 mF cm−2) is obtained at a scan rate of 2 mV s−1, while the specific capacitance of pure MnO2 nanowire electrode is 319.6 F g−1. The electrochemical impedance spectroscopy measurements also confirm MnO2 nanowire/ZnO nanorod array hybrid electrode has better electrochemical character. The MnO2 nanowire/ZnO nanorod array hybrid electrode shows great cycle stability, it only losses 6.5% of the initial capacitance after 1000 cycles. The energy density and power density of the hybrid electrode at 2 A g−1 are 63.1 Wh kg−1 and 950 W kg−1, respectively. It is illustrated that the electrochemical performance of MnO2 nanowire electrode has been greatly enhanced with the supporting of ZnO nanorod arrays.

Vertically aligned ZnO@CuS@PEDOT core@shell nanorod arrays decorated with MnO₂ nanoparticles for a high-performance and semi-transparent supercapacitor electrode.

Hybrid nano-architectures with high electrochemical performance for supercapacitors have been designed by growing hierarchical ZnO NRs@CuS@PEDOT@MnO2 core@shell heterostructured nanorod arrays on ITO/glass substrates. This hybrid nano-structured electrode exhibits excellent electrochemical performance, with a high specific areal capacitance of 19.85 mF cm(-2), good rate capability, cycling stability and diffused coloured transparency.

Graphene nanosheet–CNT hybrid nanostructure electrode for a proton exchange membrane fuel cell

This work demonstrates two-step growth of graphene nanosheets (GNS), in which carbon nanotubes (CNTs) are grown directly on a carbon cloth. GNS are subsequently constructed on the CNT surface, revealing the stand-up structure of the GNS–CNT hybrid nanostructure. The GNS–CNT hybrid nanostructure shows Nernstian and fast electron-transfer kinetics for electrochemical reactions of Fe(CN)63−/4−. A 0.1 mg cm−2 Pt/GNS–CNT is used in the cathode of a proton membrane exchange fuel cell, in which the maximum power density is 1072 mW cm−2 at 80 °C under H2/O2. In addition to a low-resistance electron-transfer pathway, the GNS–CNT hybrid nanostructure also provides numerous edge planes with strong electrochemical activity, ultimately enhancing electrochemical activity and fuel cell performance.

Carbon Nanotube–Nanocup Hybrid Structures for High Power Supercapacitor Applications

Here, we design and develop high-power electric double-layer capacitors (EDLCs) using carbon-based three dimensional (3-D) hybrid nanostructured electrodes. 3-D hybrid nanostructured electrodes consisting of vertically aligned carbon nanotubes (CNTs) on highly porous carbon nanocups (CNCs) were synthesized by a combination of anodization and chemical vapor deposition techniques. A 3-D electrode-based supercapacitor showed enhanced areal capacitance by accommodating more charges in a given footprint area than that of a conventional CNC-based device.