Nanotube Electrodes Research Articles

Simulating graphene-based single-electron transistor: incoherent current effects due to the presence of electron–electron interaction

Carbon-based nanostructures have unparalleled electronic properties. At the same time, using an allotrope of carbon as the contacts can yield better device control and reproducibility. In this work, we simulate a single-electron transistor composed of a segment of a graphene nanoribbon coupled to carbon nanotubes electrodes. Using the non-equilibrium Green's function formalism we atomistically describe the electronic transport properties of the system including electron-electron interactions. Using this methodology we are able to recover experimentally observed phenomena, such as the Coulomb blockade, as well as the corresponding Coulomb diamonds. Furthermore, we separate the different contributions to transport and show that incoherent effects due to the interaction play a crucial role in the transport properties depending on the region of the stability diagram being considered.

Microscopic in situ observation of electromechanical instability in a dielectric elastomer actuator utilizing transparent carbon nanotube electrodes.

Electromechanical instability (EMI) restricts the performance of dielectric elastomer actuators (DEAs), leading to premature electrical breakdown at a certain voltage. However, macro-level observations using traditional carbon grease electrodes have failed to capture the detailed features of EMI. In this study, we investigated EMI at the microscopic scale by fabricating transparent and conductive single-walled carbon nanotube (SWCNT) electrodes. Our findings reveal that EMI predominantly occurs in highly localized regions with dimensions on the order of tens of micrometers. This snap-through instability is likely induced by pre-existing defects within the elastomer, such as air voids or conductive particles, which reduce the critical voltage required for EMI in the flawed areas. From the perspective of phase transition principles, these defects act as heterogeneous nucleation sites for new phase embryos, thereby lowering the energy barrier for the electromechanical phase transition (i.e., EMI) compared to homogeneous nucleation in an ideally impurity-free elastomer. This study clarifies the longstanding discrepancy between theoretically predicted deformation bursts and the experimentally observed macroscopic continuous expansion of DEAs under low pre-stretch conditions. Additionally, it underscores the critical importance of material purity in mitigating electromechanical instability.

UV-A Flexible LEDs Based on Core-Shell GaN/AlGaN Quantum Well Microwires.

Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core-shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes. The electrode transparency in the UV range is optimized: namely, we demonstrate that single-walled carbon nanotube electrodes provide a stable electrical contact to the membrane with high transparency (70% at 350 nm). The flexible UV-A membrane demonstrating electroluminescence around 345 nm is further applied to excite Zn-Ir-BipyPDMS luminophores: the UV-A LED is combined with the elastic luminophore-containing membrane to produce a visible amber emission from 520 to 650 nm. The obtained results pave the way for flexible inorganic light-emitting diodes to be employed in sensing, detection of fluorescent labels, or light therapy.

High Areal Capacitance and Rate Capability of 3D-Printed Thick Electrodes with Optimized Conductive Networks from the Core-Sheath Structure.

Material extrusion 3D printing has received enormous attention to potentially overcome its limits by tailoring and designing thick electrodes. In this work, we prepared a thick reduced graphene oxide/carbon nanotube-reduced graphene oxide/carbon nanotubes/manganese oxide@carbon nanotubes (rGC-rGCMC) electrode with controlled lattice architectures, core-sheath structure, and hierarchical porosity by material coaxial extrusion 3D printing, freeze-drying, and thermal treatment. The volume ratios of core to sheath, including 100%-0%, 0%-100%, 20%-80%, 30%-70%, 40%-60%, and 50%-50%, were designed to investigate the influences of the core-sheath structure on thick electrodes. The electrodes with a core-sheath volume ratio of 30%-70% electrodes exhibited an enhanced areal specific capacitance of 588.27 mF cm-2 (39.48 F g-1) at a scan rate of 0.5 mA cm-2. All capacitance decays from core-sheath electrodes (20%-80%, 30%-70%, 40%-60%, and 50%-50%) were smaller than those from rGCMC (0%-100%) electrodes, indicating the improved rate capability from the core-sheath structure. On comparison of 30%-70% core-sheath electrodes with electrodes made of a homogeneous 30% rGC and 70% rGCMC mixture (30%+70%), lower capacitance (382.27 mF cm-2 and 25.66 F g-1 at 0.5 mA cm-2) of the 30%+70% mixture electrode without a core-sheath structure suggested less efficiency to harvest electrons from the redox reactions. Electrochemical impedance spectroscopy (EIS) data further supported and explained the resistances of thick electrodes with different volume ratios.

Self-powered wearable biosensor based on stencil-printed carbon nanotube electrodes for ethanol detection in sweat

Herein we introduce a novel water-based graphite ink modified with multiwalled carbon nanotubes, designed for the development of the first wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis. The stencil-printed graphite (SPG) electrodes, printed onto a flexible substrate, were modified by casting multiwalled carbon nanotubes (MWCNTs), electrodepositing polymethylene blue (pMB) at the anode to serve as a catalyst for nicotinamide adenine dinucleotide (NADH) oxidation, and hemin at the cathode as a selective catalyst for H2O2 reduction. Notably, alcohol dehydrogenase (ADH) was additionally physisorbed onto the anodic electrode, and alcohol oxidase (AOx) onto the cathodic electrode. The self-powered biosensor was assembled using the ADH/pMB-MWCNTs/SPG||AOx/Hemin-MWCNTs/SPG configuration, enabling the detection of ethanol as an analytical target, both at the anodic and cathodic electrodes. Its performance was assessed by measuring polarization curves with gradually increasing ethanol concentrations ranging from 0 to 50 mM. The biosensor demonstrated a linear detection range from 0.01 to 0.3 mM, with a detection limit (LOD) of 3 ± 1 µM and a sensitivity of 64 ± 2 μW mM−1, with a correlation coefficient of 0.98 (RSD 8.1%, n = 10 electrode pairs). It exhibited robust operational stability (over 2800 s with continuous ethanol turnover) and excellent storage stability (approximately 93% of initial signal retained after 90 days). Finally, the biosensor array was integrated into a wristband and successfully evaluated for continuous alcohol abuse monitoring. This proposed system displays promising attributes for use as a flexible and wearable biosensor employing biocompatible water-based inks, offering potential applications in forensic contexts.Graphical A novel water-based graphite ink modified with multiwalled carbon nanotubes designed for the development of a wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis.

Evolution of Retinal Neuron Fractality When Interfacing with Carbon Nanotube Electrodes.

Exploring how neurons in the mammalian body interact with the artificial interface of implants can be used to learn about fundamental cell behavior and to refine medical applications. For fundamental and applied research, it is crucial to determine the conditions that encourage neurons to maintain their natural behavior during interactions with non-natural interfaces. Our previous investigations quantified the deterioration of neuronal connectivity when their dendrites deviate from their natural fractal geometry. Fractal resonance proposes that neurons will exhibit enhanced connectivity if an implant's electrode geometry is matched to the fractal geometry of the neurons. Here, we use in vitro imaging to quantify the fractal geometry of mouse retinal neurons and show that they change during interaction with the electrode. Our results demonstrate that it is crucial to understand these changes in the fractal properties of neurons for fractal resonance to be effective in the in vivo mammalian system.

Novel application of carbon nanotube electrodes for electrochemical detection of amino acids in athlete’s biological samples

Understanding different physiological processes and spotting any health problems, especially in athletes, depend on tracking the quantities of amino acids in biological samples. This study looked at the creation of a unique electrochemical sensor for the sensitive and targeted identification of the necessary amino acid methionine in biological materials. Based on a modified glassy carbon electrode (GCE) surface, the sensor incorporated a tungsten disulfide (WS2) and carbon nanotube (CNT) nanocomposite. The improved electrical conductivity and catalytic activity of this material combination towards methionine oxidation led to its selection. The sensor that was created showed remarkable selectivity for methionine over other amino acids, along with a wide linear range of 5–1475 μM and a low detection limit of 10 nM. A relative standard deviation of 3.62 % was obtained across ten consecutive measurements, confirming the sensor's repeatability. The practical use of the CNTs-WS2/GCE sensor was verified by the detection of MTN in human blood serum, urine, and food samples. The recovery values ranged from 93.00 % to 99.40 %, and the relative standard deviation was less than 4.71 %. Based on these findings, we believe that our new CNTs-WS2/GCE sensor holds great potential for quick and precise methionine identification in biological samples from athletes.

The Hydroxylated Carbon Nanotubes as the Hole Oxidation System in Electrocatalysis.

The hydroxylated carbon nanotubes (CNTs-OH), due to their propensity to trap electrons, are considered in many applications. Despite many case studies, the effect of the electronic structure of the CNT-OH electrode on its oxidation properties has not received in-depth analysis. In the present study, we used Fe(CN)63-/4- and Ru(NH3)63+/2+ as redox probes, which differ in charge. The CNT-OH and CNT electrodes used in the cyclic voltammetry were in the form of freestanding films. The concentration of holes in the CNTs-OH, estimated from the upshift of the Raman G-feature, was 2.9×1013 cm-2. The standard rate constant of the heterogeneous electron transfer (HET) between Fe(CN)63-/4- and the CNTs-OH electrode was 25.9×10-4 cm·s-1. The value was more than four times higher than the HET rate on the CNT electrode (ks=6.3×10-4 cm·s-1), which proves excellent boosting of the redox reaction by the holes. The opposite effect was observed for the Ru(NH3)63+/2+ redox couple. While the redox reaction rate constant at the CNT electrode was 1.4×10-4 cm·s-1, there was a significant suppression of the redox reaction at the CNT-OH electrode (ks<0.1×10-4 cm·s-1). Based on the DFT calculations and the Gerischer model, we find that the boosting of the HET from the reduced form of the redox couple to CNT-OH occurs when the reduced forms of the redox couples are negatively charged and the occupied reduced states are aligned with acceptor states of the nanotube electrode.

Application of porous carbon nanoelectrode materials for lithium-ion batteries

Abstract In order to achieve carbon neutrality and gradually improve the current global warming environmental situation, the world’s major research teams are committed to developing lithium-ion batteries with better performance, trying to use in various new energy facilities, such as electric vehicles, which can effectively reduce polluting gas emissions. Nowadays, many electrode materials that can improve the performance of lithium-ion batteries have been continuously emerging, such as carbon nanotubes and silicon-based nanomaterials. However, carbon nanotube electrode materials have the disadvantages of high irreversible capacity, voltage lag and high manufacturing cost, while silicon-based nanomaterials also have the drawbacks of volume expansion and poor electrical conductivity. Based on the mature research of carbon materials, extensive raw material sources and large reserves, completely non-toxic and low comprehensive cost, this research analyzes three new porous carbon nanoelectrode materials with high development potential, and shows their electrochemical performance advantages, such as high charge-discharge specific capacity, excellent rate performance, and low charge transfer impedance.

Silver@copper-polyaniline nanotubes: Synthesis, characterization and biosensor analytical study

We introduce silver-copper nanoparticles incorporated into polyaniline (PANI) nanotubes using a straightforward and efficient reduction process. In this regard, PANI nanotubes with amine groups were fabricated through oxidation polymerization, followed by the attachment of Ag and Cu precursors to enable the synthesis of Ag-Cu bimetallic nanoparticles (NPs) on the pre-formed PANI nanotubes with the use of hydrazine as a reducing agent. The structural characterization of the synthesized NPs was investigated by UV–Vis spectrophotometer (UV–Vis), Dark-field emission, (EDX), X-ray diffraction (XRD) and field emission (FESEM), while the electrochemical properties were estimated by (CV) and differential pulse voltammetry (DPV). The findings indicated that the Ag-Cu NPs were present in the nanoscale range, well-dispersed, and attached to the surface of PANI nanotubes. Electrochemical investigations revealed that the Ag-Cu@PANI nanotube electrode demonstrated efficient electrooxidation of dopamine and hydroquinone without any interfering reactions, suggesting its potential use as an electrochemical biosensor for simultaneous detection of dopamine and hydroquinone. The proposed NPs-based biosensor was connected to concurrently identify dopamine and hydroquinone, illustrating moo distinguish Confinements of 0.46 µM for dopamine and 0.23 mM for hydroquinone, separately. Additionally, the manufactured sensor identified on a wide direct run the dopamine (5–25 µM), and hydroquinone (0.5–2.5 mM). Alongside these promising comes about, the Ag-Cu@PANI nanotube actualized great solidness and reproducibility, making it a favorable stage for electrochemical biosensing of dopamine and hydroquinone.

Application of Poly Dl‐Phenylalanine Modified Carbon Nanotube Electrode for Sensitive and Selective Detection of Tinidazole

AbstractThe present study aimed to design an electrochemical sensor for the detection of tinidazole (TN) by carbon nanotube electrode (CNTE) modified with dl‐phenylalanine (DL‐PA). The unmodified carbon nanotube electrode (UMCNTE) and poly (DL‐PA) modified carbon nanotube electrode (P(DL‐PA) MCNTE) were characterized by Scanning emission microscopy (SEM) images. Electrochemical techniques like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), were implemented to evaluate the efficiency of the developed electrode toward the detection of TN. The impact of pH on the modified electrode showed that the P(DL‐PA) MCNTE gave a good voltammetric response at pH 3.5. The effect of accumulation time, scan rate, and variation of concentration of TN at the surface of the developed sensor was analyzed. The scan rate study showed that the reduction reaction of TN involves a two‐electron transfer process and it is adsorption‐controlled. The detection limit studies for CV and DPV gave good linearity in the linear range 0.6 μM to 100.0 μM and 3.0 μM to 100.0 μM respectively. The limit of quantification (LOQ) and limit of detection (LOD) concerning CV were found to be 0.65 μM and 0.19 μM respectively. The LOQ and LOD for DPV were calculated to be 0.33 μM and 0.10 μM respectively. The P(DL‐PA) MCNTE showed good anti‐interferent properties. The developed sensor has good stability, repeatability, and reproducibility for the analysis of TN. The P(DL‐PA) MCNTE was successfully employed in the real sample analysis.

Porous Azatruxene Covalent Organic Frameworks for Anion Insertion in Battery Cells.

Covalent organic frameworks (COFs) containing well-defined redox-active groups have become competitive materials for next-generation batteries. Although high potentials and rate performance can be expected, only a few examples of p-type COFs have been reported for charge storage to date with even fewer examples on the use of COFs in multivalent ion batteries. Herein, we report the synthesis of a p-type highly porous and crystalline azatruxene-based COF and its application as a positive electrode material in Li- and Mg-based batteries. When this material is used in Li-based half cells as a COF/carbon nanotube (CNT) electrode, a discharge potential of 3.9 V is obtained with discharge capacities of up to 70 mAh g-1 at a 2 C rate. In Mg batteries using a tetrakis(hexafluoroisopropyloxy)borate electrolyte, cycling proceeds with an average discharge voltage of 2.9 V. Even at a fast current rate of 5 C, the capacity retention amounts to 84% over 1000 cycles.

Highly Sensitive Detection of Hydrogen Peroxide in Cancer Tissue Based on 3D Reduced Graphene Oxide-MXene-Multi-Walled Carbon Nanotubes Electrode.

Hydrogen peroxide (H2O2) is a signaling molecule that has the capacity to control a variety of biological processes in organisms. Cancer cells release more H2O2 during abnormal tumor growth. There has been a considerable amount of interest in utilizing H2O2 as a biomarker for the diagnosis of cancer tissue. In this study, an electrochemical sensor for H2O2 was constructed based on 3D reduced graphene oxide (rGO), MXene (Ti3C2), and multi-walled carbon nanotubes (MWCNTs) composite. Three-dimensional (3D) rGO-Ti3C2-MWCNTs sensor showed good linearity for H2O2 in the ranges of 1-60 μM and 60 μM-9.77 mM at a working potential of -0.25 V, with sensitivities of 235.2 µA mM-1 cm-2 and 103.8 µA mM-1 cm-2, respectively, and a detection limit of 0.3 µM (S/N = 3). The sensor exhibited long-term stability, good repeatability, and outstanding immunity to interference. In addition, the modified electrode was employed to detect real-time H2O2 release from cancer cells and cancer tissue ex vivo.

Role of the MnCoGe alloys to enhance the capacitance of flexible supercapacitors made with electrodes of recycled aluminum and carbon nanotubes

Flexible and sustainable supercapacitors (SCs) were fabricated with carbon nanotubes (CNTs) as the anode and recycled aluminium as the cathode (obtained from soda cans). Devices made with the configuration of CNT//Al had maximum energy-densities/capacitances of 97.8 Wh kg−1/313.5 F g−1. Later, MnCoGe (MCG) alloy powders doped with boron (MCG:B) or gallium (MCG:Ga) were incorporated into the SC electrodes and the energy-density/capacitance was enhanced up to 269.5 Wh kg−1/862.3 F g−1. This outstanding increment of the electrochemical performance was caused by the formation of multiple redox centers on the SC electrodes (oxygen vacancies, Mn3+/Mn4+, Co2+/Co3+, and Ge4+/Ge2+/Ge0) as confirmed by XPS and Raman spectroscopies. The SCs made with MCG alloys were immersed in acid (pH=3)/basic (pH=11) aqueous media and electrochemically tested. Surprisingly, the capacitance retention was reduced a maximum of 0.6%, demonstrating their capacity to operate underwater. The tests of bending and charging/discharging cycles demonstrated that the SCs made with the MCG:B powder were the most stable because their capacitance retention was above 95%. In contrast, SCs made with the MCG:Ga alloy had capacitance retentions below 93% after the same tests. Overall, we demonstrated that efficient/flexible/waterproof SCs can be made with low-cost aluminium, which of interest for wearable electronics.

Selective chemical doping of carbon nanotube conductors to reduce contact resistance with copper in ultrasonic welds

Electrochemical devices such as batteries, fuel cells, and capacitors employing a carbon nanotube (CNT) electrode can be improved by lowering the contact resistance between CNTs and metallic contacts. The current work investigates two simultaneous strategies to enhance the contact by using chemical doping of CNTs with potassium tetrabromoaurate (KAuBr4) and ultrasonic welding to a metal foil. The specific contact resistivity was measured using the transfer length method (TLM) to evaluate CNT test structures having ultrasonically welded Cu contacts with and without KAuBr4 doping. Purified CNT-Cu samples had a specific contact resistivity of 5.4 mΩ cm2, whereas the KAuBr4 doped CNT-Cu samples were 2.2 mΩ cm2. Confirmation of selective doping to the weld region was made using measured differences in the emissivity of purified and KAuBr4 doped CNTs, which were 0.84 and 0.56, respectively. The lower contact resistance from KAuBr4 doped CNT-Cu ultrasonic welds also reduced the extent of Joule heating beyond the contact region when applying increasing current to failure in a 2-terminal test structure. The benefit of selectively doped CNT-Cu welds was demonstrated across rectangular ribbon and electrode form factors up to an area of 6 cm × 8 cm (typical of electrochemical pouch-cell current collectors). Each form factor showed a 1.5× reduction in peak temperature when selective doping of the CNTs was performed prior to ultrasonic welding of the Cu contact. Thus, the combination of selective doping and ultrasonic welding demonstrates a viable method to fabricate low electrical resistance between CNT electrodes and metallic contacts for electrochemical devices.

Ultrasensitive Label-Free Electrochemical Immunosensor for Carbohydrate Antigen-125 (CA125) Employing Cu(II)-Polyethyleneimine (PEI)/Silica Nanoparticle@Overoxidized Polypyrrole (OPPy)/Multi-Walled Carbon Nanotubes (MWNTs) Hybrid Nanomaterial

Novel electroactive nanotags of Cu(II) functionalized polyethylenimine (PEI)/SiO2 nanoparticles (abbreviated as Cu2+/PEI/SiO2 NPs) were conveniently synthesized using a strong coordination reaction between Cu(II) and the multi-amino groups of PEI. These electroactive nanotags were easily coated on the overoxidized polypyrrole (OPPy) modified Nafion/multi-walled carbon nanotubes (abbreviated as Nafion/MWNTs) electrode surface through Cu-N bonds and strong electrostatic interactions. The Cu2+/PEI/SiO2 NPs@OPPy/MWNTs hybrid nanomaterial was formed without the addition of extra membrane-forming substances. The experimental results demonstrate that the OPPy/MWNTs composite membrane coupled with electrocatalytic Cu(Tris)4 2+ complexes in tris(hydroxymethyl)aminomethane (Tris)-HCl buffer medium amplified the electrochemical signals of nanotags based on the mutual synergistic effects. As an application, a label-free electrochemical immunosensor for epithelial ovarian cancer biomarker-carbohydrate antigen-125 (CA125) was constructed by covalently immobilizing CA125 antibody onto the hybrid nanomaterial modified electrode. With the increasing concentrations of CA125 antigen, different decreases in the electrochemical signals of the nanotags were observed due to the formation of antigen-antibody immune complexes. The electrochemical immunosensor showed a linear relationship from 0.001 to 500 U·mL−1 for CA125 with a detection limit of 3.4 × 10−4 U·mL−1. In addition, the proposed immunosensor was applied to the determination of CA125 in human serum with satisfactory results.

Enhanced ammonia oxidation by a photoelectrocatalysis‑chlorine system: The role of ClO• and free chlorine

The decomposition of ammonia-N to environmental-friendly N2 remains a fundamental problem for water treatment. We proposed a way to selectively and efficiently oxidize ammonia to N2 through an integrated photoeletrocatalysis‑chlorine reactions (PECCl) system based on a bifunctional TiO2 nanotube photoanode. The ·OH and HClO can be simultaneously generated on the TiO2 nanotube photoanode in this system, which can in situ form ClO· for efficient ammonia removal. Compared with electrochemical‑chlorine (EC-Cl), photocatalysis‑chlorine (PC-Cl) and photoelectrocatalysis (PEC) systems, the PEC-Cl system exhibited much higher electrocatalytic activity due to the synergetic effect of photoelectrocatalyst and electrocatalyst in bifunctional TiO2 nanotube electrode. The removal efficiency of ammonia-N and total-N reached 100.0 % and 93.3 % at 0.3 V (vs Ag/AgCl) in the PEC-Cl system. Moreover, the system was efficient under various pH conditions. The reactions between ClO−/ClO· and the N-containing intermediates contributed to the high performance of the system, which expanded the reactions from the electrode surface to the electrolyte. Furthermore, radical scavenging and free chlorine determination experiments confirmed that ClO· and free chlorine were the main active species that enabled the ammonia oxidation. This study presents new understanding on the role of active species for ammonia removal in wastewater.

Transparent vertical nanotube electrode arrays on graphene for cellular recording and optical imaging

Here, we report the fabrication of transparent multichannel vertical nanotube electrode arrays for detecting cellular activity and optically imaging neuronal networks. To fabricate these transparent electrode arrays, position- and morphology-controlled ZnO nanotube arrays consisting of ultrathin nanowalls were grown on transparent graphene layers and coated with Ti/Au metal layers. Using these multichannel arrays, electrophysiological signals were individually recorded from primary mouse hippocampal neurons and recorded distinctive intracellular potential-like signals. Moreover, the transparent electrode array enabled fluorescence imaging of neuron cell bodies and neurite connections. This transparent graphene- and nanotube-based recording device is proposed to greatly increase the versatility of capabilities for investigating neuronal activity through simultaneous recording and imaging of neuron cultures.

Semi‐transparent metal electrode‐free all‐inorganic perovskite solar cells using floating‐catalyst‐synthesized carbon nanotubes

AbstractPerovskite solar cells offer a promising future for next‐generation photovoltaics owing to numerous advantages such as high efficiency and ease of processing. However, two significant challenges, air stability, and manufacturing costs, hamper their commercialization. This study proposes a solution to these issues by introducing a floating catalyst‐based carbon nanotube (CNT) electrode into all‐inorganic perovskite solar cells for the first time. The use of CNT eliminates the need for metal electrodes, which are primarily responsible for high fabrication costs and device instability. The nanohybrid film formed by combining hydrophobic CNT with polymeric hole‐transporting materials acted as an efficient charge collector and provided moisture protection. Remarkably, the metal‐electrode‐free CNT‐based all‐inorganic perovskite solar cells demonstrated outstanding stability, maintaining their efficiency for over 4000 h without encapsulation in air. These cells achieved a retention efficiency of 13.8%, which is notable for all‐inorganic perovskites, and they also exhibit high transparency in both the visible and infrared regions. The obtained efficiency was the highest for semi‐transparent all‐inorganic perovskite solar cells. Building on this, a four‐terminal tandem device using a low‐band perovskite solar cell achieved a power conversion efficiency of 21.1%. These CNT electrodes set new benchmarks for the potential of perovskite solar cells with groundbreaking device stability and tandem applicability, demonstrating a step toward industrial applications.image

A Supercapacitor Architecture for Extreme Low‐Temperature Operation Featuring MXene/Carbon Nanotube Electrodes with Vertically Aligned Channels and a Novel Freeze‐Resistant Electrolyte

AbstractThe electrochemical performance of supercapacitors drops precipitously at extreme low temperatures due to a multitude of reasons, which includes electrolyte freezing, sluggish ion transport in the electrode and electrolyte, and high charge transfer resistance at electrode–electrolyte interfaces. To address high interface resistance, a new supercapacitor architecture is reported, in which MXene/carbon nanotube electrodes with vertically aligned channels are synthesized to reduce tortuosity and maximize the electrode–electrolyte contact area. These electrodes are fabricated using a directional‐freezing strategy, generating direct and fast ion transport pathways. Further, a freeze‐resistant electrolyte which shows high ionic conductivity is synthesized by designing a double‐crosslinked polymer network in a binary solvent consisting of ionic liquid and water, which exhibits an ultralow freezing temperature of −54 °C. An all‐in‐one supercapacitor is assembled by an integrated polymerization strategy to minimize interfacial resistances. The resulting device delivers a specific capacitance of 231 F g−1 at 2 mV s−1 and a maximum energy density of 10.17 Wh kg−1, while maintaining a capacitance retention of 92%, even at an extreme low temperature of −50 °C. The supercapacitor architecture developed in this study, demonstrates the feasibility of electrochemical energy storage at extreme low temperatures.