DRILL Interface Makes Ion Soft Landing Broadly Accessible for Energy Science and Applications.

The rational design of improved electrode–electrolyte interfaces (EEI) for energy storage is critically dependent on a molecular-level understanding of ionic interactions and nanoscale phenomena. The presence of non-redox active species at EEI has been shown to strongly influence Faradaic efficiency and long-term operational stability during energy storage processes. Herein, we achieve substantially higher performance and long-term stability of EEI prepared with highly dispersed discrete redox-active cluster anions (50 ng of pure ∼0.75 nm size molybdenum polyoxometalate (POM) anions on 25 μg (∼0.2 wt%) carbon nanotube (CNT) electrodes) by complete elimination of strongly coordinating non-redox species through ion soft landing (SL). Electron microscopy provides atomically resolved images of a uniform distribution of individual POM species soft landed directly on complex technologically relevant CNT electrodes. In this context, SL is established as a versatile approach for the controlled design of novel surfaces for both fundamental and applied research in energy storage.

Experimental study and CFD modelling of a two-phase slug flow for an airlift tubular membrane

Corona discharges with metal electrodes have been extensively studied both experimentally and theoretically, but the discharges on carbon nanotubes electrodes have not been reported. An experimental study of corona discharge on aligned multi-walled carbon nanotubes electrode at atmospheric pressure was made in this paper. The fabrication of aligned multi-walled carbon nanotubes (MWCNTs)electrode and measuring system of corona discharge were presented. The breakdown voltage and corona pulses on nanotubes electrode were discussed as compared with aluminum electrodes. It was found that the breakdown voltage reduced largely by using nanotubes electrode, and the repetition rate of nanotube pulses was much higher than that of metal pulses. The mechanisms of positive and negative corona pulse and the field emission of carbon nanotubes were all also discussed in detail. The experimental results showed that the positive corona has a more steady current before breakdown and more regular pulse after breakdown compared with negative corona, so the MWCNTs anode would be used in the carbon nanotubes gas sensor.

Ionic liquid (IL) electrolytes and carbon nanotube (CNT) electrodes have exhibited promising electrochemical performance in supercapacitors. Nevertheless, the adaptability of tricationic ILs (TILs) in CNT-based supercapacitors remains unknown. Herein, the performance of supercapacitors with (6,6), (8,8), (12,12), and (15,15) CNT electrodes in the TIL [C6(mim)3](Tf2N)3 was assessed via molecular dynamics simulations, paying attention to the electric double-layer (EDL) structures and the relations between the CNT curvature and capacitance. The results disclose that counterion and co-ion number densities near CNT electrodes have a marked reduction, compared with that of the graphene electrode. The capacitance of the EDL in the TIL increases significantly as the CNT curvature increases and the capacitance of the TIL/CNT systems is higher than that of the TIL/graphene system. Moreover, different EDL structures in the TIL and the monocationic IL (MIL) [C6mim][Tf2N] near CNT electrodes were revealed, showing higher-concentration anions [Tf2N]- at the CNT surfaces in the TIL. It is also verified that the TIL has a greater energy-storage ability under high potentials. Furthermore, the almost flat or weakly camel-like capacitance-voltage (C-V) curve of EDLs in the TIL turns into a bell shape in the MIL, because of the ion accumulation at the CNT surfaces and the associations between ions.

The reliable integration of carbon nanotube (CNT) electrodes in future neural probes requires a proper embedding of the CNTs to prevent damage and toxic contamination during fabrication and also to preserve their mechanical integrity during implantation. Here we describe a novel bottom-up embedding approach where the CNT microelectrodes are encased in SiO(2) and Parylene C with lithographically defined electrode openings. Vertically aligned CNTs are grown on microelectrode arrays using low-temperature plasma-enhanced chemical vapor deposition compatible with wafer-scale CMOS processing. Electrodes with 5, 10, and 25 μm diameter are realized. The CNT electrodes are characterized by electrochemical impedance spectroscopy and cyclic voltammetry and compared against cofabricated Pt and TiN electrodes. The superior performance of the CNTs in terms of impedance (≤4.8 ± 0.3 kΩ at 1 kHz) and charge-storage capacity (≥513.9 ± 61.6 mC/cm(2)) is attributed to an increased wettability caused by the removal of the SiO(2) embedding in buffered hydrofluoric acid. Infrared spectroscopy reveals an unaltered chemical fingerprint of the CNTs after fabrication. Impedance monitoring during biphasic current pulsing with increasing amplitudes provides clear evidence of the onset of gas evolution at CNT electrodes. Stimulation is accordingly considered safe for charge densities ≤40.7 mC/cm(2). In addition, prolonged stimulation with 5000 biphasic current pulses at 8.1, 40.7, and 81.5 mC/cm(2) increases the CNT electrode impedance at 1 kHz only by 5.5, 1.2, and 12.1%, respectively. Finally, insertion of CNT electrodes with and without embedding into rat brains demonstrates that embedded CNTs are mechanically more stable than non-embedded CNTs.

FBAR devices with carbon nanotube (CNT) electrodes have been developed with the aim of taking advantage of the low density and high acoustic impedance of the CNTs compared to other known materials. The influence of the CNTs on the frequency response of the FBAR devices was studied by comparing two identical sets of devices, one set comprised FBARs fabricated with chromium/gold bilayer electrodes, and the second set comprised FBARs fabricated with CNT electrodes. It was found that the CNTs had a significant effect on attenuating travelling waves at the surface of the FBARs membranes due to their high elastic stiffness. Finite element analysis of the devices fabricated was carried out using COMSOL Multiphysics, and the numerical results confirmed the experimental results obtained.

In perovskite solar cells (PSCs), expensive gold or silver metal has traditionally been utilized as the rear electrode for highly efficient performance. In this context, carbon nanotube (CNT) electrodes have been considered promising rear electrodes because of their excellent electrical conductivity, mechanical strength, and chemical stability in PSCs. Despite these favorable characteristics, concerns have been raised about the power conversion efficiency (PCE) and stability of PSCs based on CNTs due to the porosity of CNT electrodes. In this study, we employed both poly(triarylamine) (PTAA) infiltration and rear electrode hidden encapsulation approaches to address issues related to the porosity of thin‐walled carbon nanotube (TWCNT) electrodes to achieve high efficiency and stability. The infiltration of low‐molecular‐weight PTAA into the TWCNT electrode reduced electrode porosity while simultaneously improving the interfacial contact of the TWCNT layer with the perovskite layer. Furthermore, a novel encapsulation design was employed to prevent air and water exposure of the TWCNT electrode, which significantly enhanced device stability. PSCs with TWCNT rear electrodes developed on the basis of these strategies have the best PCE of 19.5% and show long‐term stability, retaining 96% and 74% of the initial PCE after 225 h at maximum power point tracking under AM 1.5G illumination and 916 h at 85°C/85% relative humidity, respectively.image

Lithium-ion cycling performance of multi-walled carbon nanotube electrodes and current collectors coated with nanometer scale Al2O3 by atomic layer deposition

We have fabricated electrochemical biological sensors based on directly synthesized carbon nanotube (CNT) electrodes. Since CNTs have a large specific surface area, the direct synthesis of CNTs on electrodes in amperometric biosensors is expected to significantly enhance electroactive surface area. Moreover, in electrochemical detections, CNT electrodes promote electron-transfer reactions on CNT surfaces. In this section, we have investigated the technology and performance of the electrochemical biosensors based on CNT electrodes and described microfluidic chips with multibiosensors based on CNT electrodes for commercialization.

Detection of oxidized LDL using a carbon nanotube electrode

High-flow nasal cannula oxygen therapy is superior to conventional oxygen therapy but not to non-invasive mechanical ventilation in reducing intubation rate in hypoxia and dyspnea due to acute heart failure: a systematic review and meta-analysis.

Electric double layer capacitors (EDLCs) are a category of supercapacitors that generally compliment the performance of batteries through delivery of high power with significantly longer cycle life. The conventional active electrode material utilized in these EDLCs is activated carbon (AC) possessing high surface area through templated porosity. However, one of the primary limitations with AC-based supercapacitors using organic electrolytes is the operational voltage maximum around 2.75 V. Operation at higher voltages that push the 2.75 V barrier is the next essential developmental breakthrough to enable significant boosts to both energy and power densities of supercapacitors. Research into alternative active electrode materials is equally critical to enable and support high voltage operation of supercapacitors. This work demonstrates the fabrication of carbon nanotube (CNT) electrodes from organic-based dispersions without the inclusion of surfactant or binder, and subsequent assembly into supercapacitor devices. The performance of pouch cells assembled from the CNT electrodes and using conventional organic electrolytes at operating voltages ≥ 2.7 V is discussed. A significant and linear voltage dependence of capacitance (~ 3 times higher than AC) was observed for cells with CNT electrodes up to operational voltages ~ 3.5 V, which are currently not achievable using AC-based cells. Repeatable charge-discharge operation of the CNT-based EDLCs was demonstrated at 3.5 V and 70°C, with consequential increase to capacitance by ~ 25 - 30 % compared to 2.7 V operation. Power and energy densities were increased by 1.5 and 2 times respectively at 3.5 V compared to operation at 2.7 V. The performance characteristics from such CNT-based pouch cells were benchmarked against commercial-grade AC supercapacitor devices using organic electrolytes and rated at 2.75 V (single cell). Long-term performance advantages were observed for the CNT-based monocells at 3.5 V and 70°C, which passed 100k cycling tests at full discharge. Under the same test conditions, commercial AC-based cells failed early during the 100k cycling. Response times approaching 2 ms (at -45° phase angle) were also demonstrated with EDLC devices using thin CNT electrodes with 1 mF capacitance. Such EDLC devices may potentially rival aluminum electrolytic capacitors (AECs) for alternating current line-filtering applications, offering significant space savings compared to the bulky AEC components. Finally, the scalable fabrication of binder-free CNT electrodes from surfactant-free dispersion of the material was demonstrated by roll-to-roll, slot-die coating onto an Al foil current collector. The processing of these conformal CNT coatings, assembly into 18650 cylindrical cells, and the resulting EDLC performance characteristics are discussed. The CNT-based 18650 cells had an average capacitance of 7 F at 2.7 V, with low average ESR of 7 mΩ at 1 kHz, and average response time of 120 ms at -45° phase angle. Figure 1

This paper demonstrates a novel flexible carbon nanotubes (CNTs) electrode array for neural recording. In this device, the CNTs electrode arrays are partially embedded into the flexible Parylene-C film using a batch microfabrication process. Through this fabrication process, the CNTs can be exposed to increase the total sensing area of an electrode. Thus, the flexible CNTs electrode of low impedance is realized. In application, the flexible CNTs electrode has been employed to record the neural signal of a crayfish nerve cord for in vitro recording. The measurements demonstrate the superior performance of the presented flexible CNTs electrode with low impedance (11.07 kΩ at 1 kHz) and high peak to peak amplitude action potential (about 410 µV). The simultaneous recording of the flexible CNTs electrode array is also demonstrated.

For a better understanding of the mechanisms of dye-sensitized solar cells (DSSCs), based on carbon nano-tube (CNT) electrodes, a phenomenological model is proposed. For modelling purposes, the meso-scopic porous CNT electrode is considered as a homogeneous nano-crystalline structure with thickness L. The CNT electrode is covered with light-absorbing dye molecules, and interpenetrated by the tri-iodide (I−/I3−) redox couple. A simulation platform, designed to study coupled charge transport in such cells, is presented here. The work aims at formulating a mathematical model that describes charge transfer and charge transport within the porous CNT window electrode. The model is based on a pseudo-homogeneous active layer using drift–diffusion transport equations for free electron and ion transport. Based on solving the continuity equation for electrons, the model uses the numerical finite difference method. The numerical solution of the continuity equation produces current–voltage curves that fit the diode equation with an ideality factor of unity. The calculated current–voltage (J–V) characteristics of the illuminated idealized DSSCs (100 mW cm−2, AM1.5), and the different series resistances of the transparent conductor oxide (TCO) layer were introduced into the idealized simulated photo J–V characteristics. The results obtained are presented and discussed in this paper. Thus, for a series resistance of 4 Ω of the TCO layer, the conversion efficiency (η) was 7.49% for the CNT-based cell, compared with 6.11% for the TiO2-based cell. Two recombination kinetic models are used, the electron transport kinetics within the nano-structured CNT film, or the electron transfer rate across the CNT–electrolyte interface. The simulations indicate that both electron and ion transport properties should be considered when modelling CNT-based DSSCs and other similar systems. Unlike conventional polycrystalline solar cells which exhibit carrier recombination, which limits their efficiency, the CNT matrix (in CNT-based cells) serves as the conductor for majority carriers and prevents recombination. This is because of special conductivity and visible–near-infrared transparency of the CNT. Charge transfer mechanisms within the porous CNT matrix and at the semiconductor–dye–electrolyte interfaces are described in this paper.

The development of portable and robust biosensors that exhibit a superior sensitive response and reasonable long‐term stability has gained significant attention especially for monitoring human health and physical conditions. Since lactate levels in blood are a long established indicator for the physical fitness in humans, our long term goal is to develop a stable enzyme‐based biosensor for monitoring human health. The model protein for this sensor is lactate oxidase (Lox). In order to construct the biosensor, the protein was attached to a carbon nanotube (CNT) electrode. The use of CNT electrodes will help not only to warrant proper immobilization of the biomolecule to the sensor but also to provide the highest sensitivity during sensing. The central hypothesis of this work is that the use of a covalent immobilization method to attach the protein onto the CNT sensor will positively affect the long‐term stability of the sensor. To address this aim, lactate oxidase (Lox) was covalently attached to the CNT electrode via EDC‐carbodiimine coupling to provide a durable attachment. This will avoid the loss of protein via leaching when it is in contact with the analyte solution during analysis thus enhancing the long‐term stability of the sensor. Cyclic voltammetry and amperometric experiments were conducted to study the biosensor response, the sensitivity, and the detection limits. XPS demonstrated the covalent attachment of Lox onto the CNT electrode. Temperature experiments were conducted in order to study the stability of the sensor. Our results, demonstrate that the covalently immobilization of the protein onto the CNT sensor increased significantly the long‐term stability of the biosensor.