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Action spectroscopies use a readout created by the action of light on the molecules or material rather than optical absorption. Ultrafast 2D photocurrent and 2D fluorescence spectroscopies are two such action spectroscopies. Despite their utility, multidimensional action spectroscopies suffer from a background created by incoherent population mixing. These backgrounds appear when the action of one molecule impacts that of another, creating a signal that mimics a fourth-order population response but is really just the convolution of two linear responses. The background created by incoherent mixing is often much larger than the desired foreground signals. In this paper, we describe the physical mechanisms that give rise to the incoherent signals, drawing Feynman paths for each. There are three variations of incoherent signals, differing by their pulse ordering. They all have the same phase dependence as the desired fourth-order population signals and so cannot be removed by standard phase cycling, but they do differ in their polarization responses and dephasing times. We propose, and implement, a spectrometer design that eliminates the background signals for isotropically oriented samples, leaving only the desired fourth-order 2D action spectra. Our spectrometer utilizes a TWINS interferometer and a pulse shaper interferometer, each driven with a different white-light source so that the pulse pairs within each interferometer are phase stable, but not between the two. The lack of phase stability between the two interferometers eliminates two of the three incoherent responses. The third incoherent response is eliminated with the polarization scheme ⟨0, π/2, π/4, π/4⟩. Our spectrometer also enables both 2D photocurrent and 2D white-light spectra to be collected simultaneously, thereby enabling a direct comparison between action and optical detection under identical conditions and at the exact same position on the sample. Using this spectrometer and photovoltaic devices made from thin films of semiconducting carbon nanotubes, we demonstrate 2D photocurrent spectra free of incoherent background. [ABSTRACT FROM AUTHOR]

N-type carbon nanotubes (CNTs)-based field-effect transistors (FETs) have huge potential applications in low-power consumption tunnel FETs. However, the low-work function metal electrodes can achieve n-type CNTs, but they are easily oxidized due to poor environmental stability. Therefore, based on first-principles calculations, we proposed halide perovskite nanowires Cs4MX5 (M = Pb, Sn; X = Cl, Br, I) inner filling to achieve n-type single-walled CNTs (SWCNTs). The results indicated that all the perovskite nanowires located at the center of the SWCNTs possess high stability. Moreover, the diameter of SWCNTs is a crucial factor affecting the inner filling of perovskite nanowires with an optimal diameter of about 1.4 nm. Furthermore, all the perovskite nanowires Cs4MX5 are excellent electron donors, and the largest charge transfer is up to 1.72 e/nm for Cs4SnI5. Their interaction mechanism reveals that the low work function and the large internal bandgap are two important factors for cubic-phase nanowires to realize the n-type CNTs. Our findings provide some candidate materials and a feasible way to achieve n-type CNTs for applying CNTs-based FETs. [ABSTRACT FROM AUTHOR]

An investigation into second-harmonic generation from magnetized anharmonic carbon nanotubes (CNTs) mounted on a silica substrate is conducted using a Gaussian laser pulse with modulated amplitude. An intense amplitude-modulated laser pulse incident on the array of CNTs displaces their electrons generating a restoration force. This restoration force is the nonlinear function of displacement of electrons, which ensures the anharmonic behavior of CNTs. Using the paraxial ray approximation, the nonlinear interaction of the incident pulse with CNTs is expressed in terms of a wave equation derived using the perturbative technique. The nonlinear current at second-harmonic frequency arises due to the perturbation of the electron density of CNTs by the ponderomotive force exerted on them by an incident pulse. Numerical outcomes validate the enhanced efficiency of the generated harmonic when considering the phenomenon of self-focusing. With the substantial optical nonlinearities of an anharmonic CNT structure, the plasmon resonance is broadened and high efficiency in generating harmonics is attained. It is seen that the augmenting of the amplitude-modulated parameter of the pulse and the external magnetic field strength enhances system nonlinearity, resulting in increased amplitude of generated second harmonics. Additionally, the effect of the heating rate of CNTs on the efficiency of the generated harmonic is also discussed. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have potential applications in separation membranes and nanofluidic devices. It is well known that the behavior of water molecules confined in CNTs is affected by surface functional groups and external electric fields, leading to structural changes. The understanding of these structural changes of water within various CNTs is crucial, particularly in the context of material separation. While there have been many investigations into the effects of individual specific functional groups, a comprehensive understanding of the effect of these functional groups and the electric fields they generate on water molecules remains elusive. In this study, we investigate the properties of water molecules in tip-charged CNTs of (8,8), (10,10), and (12,12) chiral vectors with positive charges at one tip and negative charges at the other tip. Abstraction of ionized functional groups as tip charges enables a comprehensive understanding that is independent of individual functional groups. The symmetrically arranged tip-charges spontaneously generate a strong and symmetric electric field in the CNTs. However, the strength and directionality of the electric field are non-uniform and complex. In the interiors of (8,8) and (10,10) tip-charged CNTs, helical and square structures, which have disturbances caused by the non-uniformity of the electric field, are observed. The properties of the water molecules differed significantly in the center of the CNTs and near positive and negative charges, despite the electric field symmetry. In (12,12) tip-charged CNTs with 12 charges, a local ring structure is observed in the vicinity of negative charges but not in the vicinity of positive charges. It is concluded that the water structures in tip-charged CNTs have different characteristics from those in plain CNTs under a uniform electric field. [ABSTRACT FROM AUTHOR]

The conductivity type is one of the most fundamental transport properties of semiconductors, which is usually identified by fabricating the field-effect transistor, the Hall-effect device, etc. However, it is challenging to obtain an Ohmic contact if the sample is down to nanometer-scale because of the small size and intrinsic heterogeneity. Noncontact dielectric force microscopy (DFM) can identify the conductivity type of the sample by applying a DC gate voltage to the tip, which is effective in tuning the accumulation or depletion of charge carriers. Here, we further developed a dual-modulation DFM, which simplified the conductivity type identification from multiple scan times under different DC gate voltages to a single scan under an AC gate voltage. Taking single-walled carbon nanotubes as testing samples, the semiconducting-type sample exhibits a more significant charge carrier accumulation/depletion under each half-period of the AC gate voltage than the metallic-type sample due to the stronger rectification effect. The charge carrier accumulation or depletion of the p-type sample is opposite to that of the n-type sample at the same half-period of the AC gate voltage because of the reversed charge carrier type. [ABSTRACT FROM AUTHOR]

Nanoscale semiconductors with isolated spin impurities have been touted as promising materials for their potential use at the intersection of quantum, spin, and information technologies. Electron paramagnetic resonance (EPR) studies of spins in semiconducting carbon nanotubes have overwhelmingly focused on spins more strongly localized by sp3-type lattice defects. However, the creation of such impurities is irreversible and requires specific reactions to generate them. Shallow charge impurities, on the other hand, are more readily and widely produced by simple redox chemistry, but have not yet been investigated for their spin properties. Here, we use EPR to study p-doped (6,5) semiconducting single-wall carbon nanotubes (s-SWNTs) and elucidate the role of impurity–impurity interactions in conjunction with exchange and correlation effects for the spin behavior of this material. A quantitative comparison of the EPR signals with phenomenological modeling combined with configuration interaction electronic structure calculations of impurity pairs shows that orbital overlap, combined with exchange and correlation effects, causes the EPR signal to disappear due to spin entanglement for doping levels corresponding to impurity spacings of 14 nm (at 30 K). This transition is predicted to shift to higher doping levels with increasing temperature and to lower levels with increasing screening, providing an opportunity for improved spin control in doped s-SWNTs. [ABSTRACT FROM AUTHOR]

We outline a surface scattering kernel for rarefied gas flows through ideally ordered nanomaterials, such as high aspect ratio carbon nanotubes. The derived model allows for a comparison of the tangential momentum accommodation coefficient, and, hence, the total effective friction, for different species of gases as a function of the particle diameter. This surface kernel is incorporated with a Fokker–Planck model as an approximation to transport of a rarefied gas through ideally ordered carbon nanotubes. The results of this analysis predict that H 2 experiences higher friction in such systems in comparison with larger molecules such as C H 4 . The results are proposed as a potential explanation of the reduced gas transport of hydrogen gas in nanoporous systems. [ABSTRACT FROM AUTHOR]

Alkali metal doping of multi-walled carbon nanotubes is of great interest, both fundamentally to explore the effect of dopants on quasi-one-dimensional electrical systems and for energy applications such as alkali metal storage. We present an investigation with complementary photoemission and Raman spectroscopies, fully carried out in an ultra-high vacuum, to unveil the electronic and vibrational response of a forest of highly aligned multi-walled carbon nanotubes by in situ potassium doping. The charge donation by the alkali adatoms induces a plasmon mode, and the density of states undergoes an energy shift consistent with electron donation and band filling of the multi-walled carbon nanotube band structure. The π-states in the valence band and the Raman peaks unveil an evolution that can be ascribed to charge donation and partially to a tensile strain exerted by the K adatoms on the carbon lattice. All these effects are thermally reversible, fostering these materials as a potential system for electronic charge harvesting. [ABSTRACT FROM AUTHOR]

We observed a modification of transition pathways in polarized resonance Raman spectroscopy during tip-enhanced Raman spectroscopy (TERS) analysis of metallic carbon nanotubes (CNTs). At a spatial resolution reaching up to the sub-nanometer regime, the signal intensity of the typical D-band is observed to be even higher than the intensity of the G-band all over the probed CNTs in TERS imaging. The measured D-band is attributed to the non-vertical transitions of electrons in k-space that are facilitated by highly confined near-field light at the tip–sample junction of our scanning tunneling microscope based TERS system. The D-band signal was observed even when the CNTs were excited by light polarized perpendicular to the tube axis that corresponds to electronic excitations between different cutting line numbers of a CNT. By combining the electron pathways brought about by both the near-field light and its polarization, we found a unique optical transition of electrons of CNTs in near-field Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Dimensions and molecular structures play pivotal roles in the principle of heat conduction. The dimensional characteristics of a solution within nanoscale systems depend on the degrees of confinement. However, the influence of such variations on heat transfer remains inadequately understood. Here, we perform quasi-one-dimensional non-equilibrium molecular dynamics simulations to calculate the thermal conductivity of water molecules confined in carbon nanotubes. The structure of water molecules is determined depending on the nanotube radius, forming a single-file, a single-layer, and a double-layer structure, corresponding to an increasing radius order. We reveal that the thermal conductivity of liquid water has a sublinear dependency on nanotube length exclusively when water molecules form a single file. A stronger confinement leads to behavioral and structural characteristics closely resembling a one-dimensional nature. Moreover, single-layer-structured water molecules exhibit enhanced thermal conductivity. We elucidate that this is due to the increase in the local water density and the absence of transitions to another layer, which typically occurs in systems with double-layer water structures within relatively large radius nanotubes. [ABSTRACT FROM AUTHOR]

Understanding and further regulating the degradation of mandrel materials is a key aspect of target fabrication in inertial confinement fusion (ICF). Here, a quasi-one-dimensional confinement model is developed using a series of single-walled carbon nanotubes with varying diameters (Dm), and the degradation of poly-α-methylstyrene (PAMS) as a typical mandrel material is investigated under such confined conditions by using the combined method of quantum mechanics and molecular mechanics. In comparison to the isolated system, the calculations show that confinement can decrease or increase the energy barriers of PAMS degradation, which directly depends on Dm. Following which a clear exponential relationship between the degradation rate of PAMS and its own density is derived, indicating that the density of PAMS can be used to regulate mandrel degradation. This work highlights the important effects of confinement on degradation and provides a valuable reference for further development of polymer degradation technologies in ICF target fabrication and other fields. [ABSTRACT FROM AUTHOR]

In a recent work, we have briefly introduced a new structural index for water that, unlike previous indicators, was devised specifically for generic contexts beyond bulk conditions, making it suitable for hydration and nanoconfinement settings. In this work, we shall study this metric in detail, demonstrating its ability to reveal the existence of a fine-tuned interplay between the local structure and energetics in liquid water. This molecular principle enables the establishment of an extended hydrogen bond network, while simultaneously allowing for the existence of network defects by compensating for uncoordinated sites. By studying different water models and different temperatures encompassing both the normal liquid and the supercooled regime, this molecular mechanism will be shown to underlie the two-state behavior of bulk water. In addition, by studying functionalized self-assembled monolayers and diverse graphene-like surfaces, we shall show that this principle is also operative at hydration and nanoconfinement conditions, thus generalizing the validity of the two-liquid scenario of water to these contexts. This approach will allow us to define conditions for wettability, providing an accurate measure of hydrophobicity and a reliable predictor of filling and drying transitions. Hence, it might open the possibility of elucidating the active role of water in the broad fields of biophysics and materials science. As a preliminary step, we shall study the hydration structure and hydrophilicity of graphene-like systems (parallel graphene sheets and carbon nanotubes) as a function of the confinement dimensionality. [ABSTRACT FROM AUTHOR]

Due to fascinating physical properties powered by remarkable progress in chemical vapor deposition of high-quality epilayers, diamond thin films attract great attention for fabrication of nitrogen-vacancy-based solid-state spin systems capable of operating in ambient conditions. To date, diamond heteroepitaxy via bias-enhanced nucleation is an unavoidable method for reliable wafer-scale film manufacturing. In this work, we analyze the coalescence phenomena in nitrogen doped, heteroepitaxial diamond epilayers, with a particular focus on their specific role in the annihilation of macroscopic crystal irregularities such as grain boundaries, non-oriented grains, and twinned segments. Here, we also report on the growth mechanism for the "primary" crystal orientation along with a predominant formation of two different types of boundaries highlighting the {011}-type as a main source of the crystal lattice irregularities. [ABSTRACT FROM AUTHOR]

Many researchers observed enhanced water flow through carbon nanotubes (CNTs) and attributed the reason to large slips. Even after taking significant slip effects into account, there remain unaddressed observations of significant improvements in flow rates. As CNTS are deformable, we represent nanotubes with a deformable-wall using a linear pressure–area relationship. We assume lubrication assumption, and using the properties of nanoconfined water, we derive the model for deformable-nanotubes. We validated our derived model in its limiting cases with the previously reported results in the literature. We compare the predictions by our deformable-wall and rigid-wall model with the experimental results and the MD-simulation predictions by multiple literature studies. Many studies were well-predicted by the rigid-wall model with slips. However, we find that there are many studies with high porosity and thin wall tubes, where elasticity or deformability of the tube is essential in modeling, which is well-predicted by our deformable-wall model with slips. In our study, we focus on investigating the impact of two key factors: the deformability, and the slip length on the flow rate. We find that the flow rate inside the tube increases as the deformability increases or the thickness T and elastic modulus E of the tube-wall decrease). We also find that the flow rate in deformable tubes scales as m ˙ deformable ∼ 1 / α 0 for (Δ p / α A o ) ≪ 1 , m ˙ deformable ∼ 1 / α for (Δ p / α A o ) ∼ O (10 − 1) and m ˙ deformable ∼ α 2 for (Δ p / α A o ) ∼ O (1). Further, for a given deformability, the percentage change in flow rate in the smaller diameter of the tube is much larger than the larger diameter. As the tube diameter decreases for the given pressure, Δ m ˙ / m ˙ increases. We find that for rigid-tube, the flow rate varies m ˙ rigid ∼ Δ p , whereas for the deformable-tubes, the flow rate scales as m ˙ deformable ∼ Δ p 2 for (Δ p / α A o ) ∼ O (10 − 1) , and finally to m ˙ deformable ∼ Δ p 3 for (Δ p / α A o ) ∼ O (1). We further find that slip also significantly increases flow rate, but, deformability has more substantial effect. [ABSTRACT FROM AUTHOR]

Hybrid spin-mechanical systems offer a promising platform for advancing quantum science and technology. However, practical implementation of applications within these hybrid quantum systems demands the seamless integration of supplementary physical components. In this context, we present a proposal for a multi-mode spin-mechanical setup, featuring the utilization of three-mode coupling nanomechanical carbon nanotube (CNT) resonators. These resonators interact with each other via a phase-dependent phonon-exchange mechanism, which is coupled to the same nitrogen vacancy (NV) centers in diamond. Based on the modulation of the phonon–phonon coupling phase and leveraging the triple Fano-like resonance phenomenon, a tripling of electromagnetically induced transparency (EIT) becomes achievable within the system. This tripling is accompanied by swift dispersion, leading to a subtle advancement or delay in outcomes. The phenomenon of triple Fano-like resonance, alongside the resulting triple EIT, engenders noteworthy slow-to-fast and fast-to-slow light effects, which is theoretically demonstrated in CNT resonators, with both identical and distinct frequencies. The findings underscore that CNT resonators with varying frequencies can evoke a more pronounced transition in the slow–fast–slow and fast–slow–fast light effects. This study lays the foundation for the application of phonon-mediated optical information storage and processing. [ABSTRACT FROM AUTHOR]

It is a known and experimentally verified fact that the flow of pressure-driven nanoconfined fluids cannot be accurately described by the Navier–Stokes (NS) equations with non-slip boundary conditions, and the measured volumetric flow rates are much higher than those predicted by macroscopical continuum models. In particular, the flow enhancement factors (the ratio between the flow rates directly measured by experiments or simulations and those predicted by the non-slip NS equation) reported by previous studies have more than five orders of magnitude differences. We showcased an anomalous phenomenon in which the flow enhancement exhibits a non-monotonic correlation with fluid pressure within the carbon nanotube with a diameter of 2 nm. Molecular dynamics simulations indicate that the inconsistency of flow behaviors is attributed to the phase transition of nanoconfined fluid induced by fluid pressures. The nanomechanical mechanisms are contributed by complex hydrogen-bonding interactions and regulated water orientations. This study suggests a method for explaining the inconsistency of flow enhancements by considering the pressure-dependent molecular structures. [ABSTRACT FROM AUTHOR]

The sluggish oxygen evolution reaction (OER) in overall electrocatalytic water splitting poses a significant challenge in hydrogen production. A series of transition metal phosphides are emerging as promising electrocatalysts, effectively modulating the charge distribution of surrounding atoms for OER. In this study, a highly efficient OER electrocatalyst (CoP-CNR-CNT) was successfully synthesized through the pyrolysis and phosphatization of a Co-doped In-based coordination polymer, specifically InOF-25. This process resulted in evenly dispersed CoP nanoparticles encapsulated in coordination polymer-derived carbon nanoribbons. The synthesized CoP-CNR-CNT demonstrated a competitive OER activity with a smaller overpotential (η10) of 295.7 mV at 10 mA cm-2 and a satisfactory long-term stability compared to the state-of-the-art RuO2 (η10 = 353.7 mV). The high OER activity and stability can be attributed to the high conductivity of the carbon network, the abundance of CoP particles, and the intricate nanostructure of nanoribbons/nanotubes. This work provides valuable insights into the rational design and facile preparation of efficient non-precious metal-based OER electrocatalysts from inorganic–organic coordination polymers, with potential applications in various energy conversion and storage systems. [ABSTRACT FROM AUTHOR]

The carbon nano-peapod is a representative structure with interlayer van der Waals (vdW) interactions, in which encapsulated fullerene molecules play a critical role in modulating the transport properties of the carbon nanotubes (CNTs). In particular, their influence on the thermal transport characteristics has been the focal point of considerable attention. In this study, we trained an accurate machine learning potential for fullerene-encapsulated CNTs based on the efficient NEP model to investigate their thermal properties. Using equilibrium molecular dynamics simulation along with the spectral decomposition method for thermal conductivity, we find that the thermal conductivity of fullerene-encapsulated CNTs is roughly 55 % lower than that of empty CNTs, aligning with experimental observations for CNT bundles with fullerene encapsulation [Kodama et al., Nat. Mater. 16, 892 (2017)]. The research suggests that weak vdW interactions between both the fullerene and CNTs, as well as between fullerene molecules themselves, hinder phonon propagation. The encapsulated fullerene contributes to an increase in phonon scattering within the CNTs, ultimately leading to a reduction in thermal conductivity. We utilized machine learning potential to investigate the structure of fullerene-encapsulated CNTs and their heat transport property. This approach provides valuable insights for performance research of complex systems featuring interlayer vdW interactions. [ABSTRACT FROM AUTHOR]

Programmable locomotion of molecules inside the carbon nanotube (CNT) has a significant role in controlling the reactions and delivery systems based on nanotubes. Using molecular dynamics (MD) simulations as well as the theoretical approach, we evaluate the oscillation of C60 inside the CNTs that are subjected to strain gradients from both sides. The molecular dynamics simulations are implemented by LAMMPS open-source software. Using this program, the van der Waals (vdW) interactions are established between C60 and nanotube, and the simulations are performed in canonical ensemble. The strain gradient applied on CNT provides the restoring force of the oscillation of C60. The potential energy of fullerene finds the minimum value at the unstrained region of CNT, which makes it the equilibrium point of oscillation. The amplitude of the oscillations is shown to be related to the thermal energy of C60. The frequency of the oscillations depends on the magnitude of the strain gradient applied on the nanotubes. At higher strain gradients of CNTs, we observe the increase in the frequency due to the increase in the restoring force acting on the fullerene molecule. We exploit the strained carbon nanotubes to control the position of C60 inside the nanotube. It has been shown that by changing the strain gradient of CNT, it is possible to steer the locomotion of C60 to different points inside the nanotube. [ABSTRACT FROM AUTHOR]

For over half a century, traditional silicon-based integrated circuits (ICs) have been the basis of computational electronics and are widely used in computers, cell phones, and other fields. With the rapid development of human society, silicon-based semiconductor technology is approaching its physical and engineering limits. Our increasing diversity of non-traditional computing needs, such as ultra-small, ultra-fast, ultra-low-power wearables, and space radiation protection, is driving the search for new electronic materials. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have many excellent electrical properties, such as high carrier mobility and high ballistic transport, making them strong candidates for new semiconductor materials in the post-Moore era. Carbon-based electronic technology has been developed for over 20 years, and the fundamental issues such as the material purification of s-SWCNTs, preparation prospects of s-SWCNT-based field-effect transistors (CNT FETs), and device physics based on CNT FETs have been basically solved. However, the chiral diversity of s-SWCNTs may lead to problems such as fluctuations in the electrical performance of CNT FETs, limiting the application of s-SWCNTs in high-end ICs. Monochiral s-SWCNTs not only have excellent electrical properties but also have a controllable structure and uniformity, which are crucial for the high-end IC of CNTs. However, some problems exist in the purity and yield of monochiral s-SWCNT preparation and the optimization of monochiral CNT FETs. Therefore, the chiral sorting of CNTs is reviewed in this paper, and the progress of polymer reprocessing in chiral separation is highlighted. Then, the research progress of monochiral CNT FETs is introduced, and possible development directions are summarized and analyzed. Finally, the application prospects of chiral-enriched s-SWCNTs include challenges and future opportunities. [ABSTRACT FROM AUTHOR]

Experimental observations unambiguously reveal quasi-frictionless water flow through nanometer-scale carbon nanotubes (CNTs). Classical fluid mechanics is deemed unfit to describe this enhanced flow, and recent investigations indicated that quantum mechanics is required to interpret the extremely weak water–CNT friction. In fact, by quantum scattering, water can only release discrete energy upon excitation of electronic and phononic modes in the CNT. Here, we analyze in detail how a traveling water molecule couples to both plasmon and phonon excitations within a sub-nanometer, periodic CNT. We find that the water molecule needs to exceed a minimum speed threshold of ∼50 m/s in order to scatter against CNT electronic and vibrational modes. Below this threshold, scattering is suppressed, as in standard superfluidity mechanisms. The scattering rates, relevant for faster water molecules, are also estimated. [ABSTRACT FROM AUTHOR]

We report on the studies of conduction mechanism, direct current conductance, and 1 f -noise of cellulose nanofiber (CNF) and multiwalled carbon nanotube (MWCNT) composites. The composites were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. The temperature- and voltage-dependence of the dc conductance Σ were, respectively, probed to investigate the charge transport mechanism and the electrical response of the composite. At room temperature, the increase in Σ with wt. % of MWCNT ϕ showed typical percolation behavior. The Σ − T behavior was fitted to the combination of one-dimensional variable range hopping and the fluctuation-induced tunneling, which were attributed to hopping of charge carriers through 1D MWCNTs and the tunneling of charge carriers between the bundles of MWCNTs, respectively. The non-Ohmic electrical conduction was characterized by the onset voltage V 0 (T) which scaled with Ohmic conductance Σ 0 as V 0 (T) ∼ Σ 0 (T) x T , with x T being the onset exponent increased with ϕ. A scaling description based on the data collapse method was adopted to find the parameters V 0 (T) and x T. The noise power spectrum S V (f) followed the relation S V (f) ∼ V β with two different power-laws: β 1 in the Ohmic and β 2 in the non-Ohmic region (β 1 > --> β 2). Interestingly, this change in power-laws occurs at the same V 0 (T) obtained from Σ − V curves. A simple model was proposed to explain the noise behavior after V 0 (T). It is expected that such electrical characterization of CNF-MWCNT nanopaper composite would open up their possibility of application in flexible electronic devices, intelligent networks, sensors, and actuators. [ABSTRACT FROM AUTHOR]

The unique physical properties of carbyne, a novel carbon nanostructure, have attracted considerable interest in modern nanotechnology. While carbyne synthesis has been accomplished successfully using diverse techniques, the underlying mechanisms governing the carbon monoxide-dependent catalytic synthesis of endohedral carbyne remain poorly understood. In this simulation-based study, we investigate the synthesis of endohedral carbyne from carbon and carbon monoxide radicals in the presence of a nickel catalyst inside double-walled carbon nanotubes with a (5,5)@(10,10) structure. The outcome of our investigation demonstrates that the incorporation of the carbon atom within the Nin@(5,5)@(10,10) model system initiates the formation of an elongated carbon chain. In contrast, upon the introduction of carbon monoxide radicals, the growth of the carbyne chain is inhibited as a result of the oxidation of endohedral nickel clusters by oxygen atoms after the initial steps of nucleation. Our findings align with prior theoretical, simulation, and experimental investigations, reinforcing their consistency and providing valuable insights into the synthesis of carbyne-based nanodevices that hold promising potential for future advancements in nanotechnology. [ABSTRACT FROM AUTHOR]

Developing bifunctional catalysts for overall water splitting with high activity and durability at high current density remains a challenge. In an attempt to overcome this bottleneck, in this work, unique CoNiFe-layered double hydroxide nanoflowers are in situ grown on nickel-iron (NiFe) foam through a corrosive approach and following a chemical vapor deposition process to generate nitrogen-doped carbon nanotubes at the presence of melamine (CoNiFe@NCNTs). The coupling effects between various metal species act a key role in accelerating the reaction kinetics. Moreover, the in situ formed NCNTs also favor promoting electrocatalytic activity and stability. For oxygen evolution reaction it requires low overpotentials of 330 and 341 mV in 1M KOH and 1M KOH + seawater to drive 500 mA cm−2. Moreover, water electrolysis can be operated with CoNiFe@NCNTs as both anode and cathode with small voltages of 1.95 and 1.93 V to achieve 500 mA cm−2 in 1M KOH and 1M KOH + seawater, respectively. [ABSTRACT FROM AUTHOR]

We demonstrate a high electron conductivity (>102 S/cm and up to 103 S/cm) of tungsten suboxide W18O52.4−52.9 (or equivalently WO2.91−2.94) nanotubes (2–3 nm in diameter, ∼μm long). The conductivity is measured in the temperature range of 120–300 K by a four-probe scanning tunneling microscope in ultrahigh vacuum. The nanotubes are synthesized by a low-temperature and low-cost solvothermal method. They self-assemble in bundles of hundreds of nanotubes forming nanowires (∼μm long, few tens nm wide). We observe a large anisotropy of the conductivity with a ratio (longitudinal conductivity/perpendicular conductivity) of ∼105. A large fraction of them (∼65%–95%) shows a metallic-like, thermal activation-less electron transport behavior. Few of them, with a lower conductivity from 10 to 102 S/cm, display a variable range hopping behavior. In this latter case, a hopping barrier energy of ∼0.24 eV is inferred in agreement with the calculated energy level of the oxygen vacancy below the conduction band. This result is in agreement with a relative average concentration of oxygen vacancies of ∼3%, for which a semiconductor-to-metal transition was theoretically predicted. These tungsten suboxide nanostructures are prone to a wide range of applications in nanoelectronics. [ABSTRACT FROM AUTHOR]

The electric polarizability and the spread of the total position tensors are used to characterize the metallic vs insulator nature of large (finite) systems. Finite clusters are usually treated within the open boundary condition formalism. This introduces border effects, which prevent a fast convergence to the thermodynamic limit and can be eliminated within the formalism of periodic boundary conditions. Recently, we introduced an original approach to periodic boundary conditions, named Clifford boundary conditions. It considers a finite fragment extracted from a periodic system and the modification of its topology into that of a Clifford torus. The quantity representing the position is modified in order to fulfill the system periodicity. In this work, we apply the formalism of Clifford boundary conditions to the case of carbon nanotubes, whose treatment results in a particularly simple zigzag geometry. Indeed, we demonstrate that at the Hückel level, these nanotubes, either finite or periodic, are formally equivalent to a collection of non-interacting dimerized linear chains, thus simplifying their treatment. This equivalence is used to describe some nanotube properties as the sum of the contributions of the independent chains and to identify the origin of peculiar behaviors (such as conductivity). Indeed, if the number of hexagons along the circumference is a multiple of three, a metallic behavior is found, namely a divergence of both the (per electron) polarizability and total position spread of at least one linear chain. These results are in agreement with those in the literature from tight-binding calculations. [ABSTRACT FROM AUTHOR]

The temperature coefficient of resistivity (θ T) of carbon-based materials is a critical property that directly determines their electrical response upon thermal impulses. It could have metal- (positive) or semiconductor-like (negative) behavior, depending on the combined temperature dependence of electron density and electron scattering. Its distribution in space is very difficult to measure and is rarely studied. Here, for the first time, we report that carbon-based micro/nanoscale structures have a strong non-uniform spatial distribution of θ T. This distribution is probed by measuring the transient electro-thermal response of the material under extremely localized step laser heating and scanning, which magnifies the local θ T effect in the measured transient voltage evolution. For carbon microfibers (CMFs), after electrical current annealing, θ T varies from negative to positive from the sample end to the center with a magnitude change of >130% over <1 mm. This θ T sign change is confirmed by directly testing smaller segments from different regions of an annealed CMF. For micro-thick carbon nanotube bundles, θ T is found to have a relative change of >125% within a length of ∼2 mm, uncovering strong metallic to semiconductive behavior change in space. Our θ T scanning technique can be readily extended to nm-thick samples with μm scanning resolution to explore the distribution of θ T and provide a deep insight into the local electron conduction. [ABSTRACT FROM AUTHOR]

The impact of a time-varying external magnetic field on carbon nanotubes has been studied using Maxwell's equations in the mentioned articles. However, the Maxwell's equations are erroneously presented in the papers. The incorrect Maxwell's equations, their derivatives, and the Lorentz force equations have all been examined in this work. In this article, we have endeavored to ensure that the equations are formatted correctly and have made an effort to do so. We have made an effort to intuitively correct the equations' errors. We did not comment on the other portions of the mentioned articles; instead, we restricted ourselves to the examination of the impact of Maxwell's equations and Lorentz force equations. [ABSTRACT FROM AUTHOR]

This study explores advancements in concurrent biorefinery and hydrogen production using Ni-decorated CNTs derived from bioethanol as electrocatalysts, showing the complete conversion of furan derivatives to the desired products with 95–97% selectivity and a hydrogen production rate of 75 μmol h−1. These findings highlight the simultaneous upgrading of biomass-derived compounds and hydrogen production. [ABSTRACT FROM AUTHOR]

Anion exchange membrane fuel cells (AEMFCs) represent a promising class of clean energy devices, with their performance being critically dependent on the efficiency of the cathode oxygen reduction reaction (ORR) catalyst. Herein, we report a highly efficient ORR catalyst based on bimetallic-doped CuMn–N–C combined with MXene and carbon nanotubes (CNT). The CuMn–N–C@MXene + CNT exhibits the half-wave potential (E 1/2) of 0.860 V and a minimal potential decay of only 4 mV after 10,000 CV cycles. These results reveal that the CuMn–N–C@MXene + CNT catalyst outperforms the conventional Pt/C catalyst in terms of both ORR activity and stability. Moreover, an AEMFC incorporating the CuMn–N–C@MXene + CNT catalyst demonstrates a power density of 317 mW cm−2 and only 2.3% performance loss after 14 h of operation. This study offers a valuable strategy for designing and synthesizing low-cost, efficient, and stable electrocatalysts for AEMFC applications. [Display omitted] • CuMn–N–C@MXene + CNT showed E 1/2 of 0.860 V and only a 4 mV day after 10,000 CV cycles. • CuMn–N–C@MXene + CNT demonstrated a power density of 317 mW cm−2 in AEMFC. • CuMn–N–C@MXene + CNT retained 97.7% of its initial current after 14 h in AEMFC. [ABSTRACT FROM AUTHOR]

The design of highly efficient catalysts applied in a wide pH range for hydrogen evolution reaction (HER) is still very challengeable. Herein, a rapid Joule heating method has been applied to deposit Ru nanoparticles onto carbon nanotubes (Ru/CNTs). Owing to the rapid heating and cooling processes during the Joule heating treatment, the lattice was disordered with exposure of massive reactive sites for HER. As tested, Ru/CNTs showed outstanding activity in HER in a wide pH range. It only required an overpotential of 21 mV and 9 mV at 10 mA cm−2 for HER in 0.5 M H 2 SO 4 and 1 M KOH, specifically. The overpotential required to achieve a current density of 1 A cm−2 in 0.5 M H 2 SO 4 and 1 M KOH was 162 mV and 360 mV, respectively. The excellent performance of Ru/CNTs was comparable to commercial Pt/C catalyst. Furthermore, using the manufactured Ru/CNTs, a homemade anion-exchange membrane AEM electrolyzer was assembled. It only required 1.87 V to reach 100 mA cm−2 with nearly 100% Faraday efficiency. This work provided a novel method to prepare Ru nanoparticles onto carbon nanotubes by a rapid Joule heating treatment for advanced HER activity in a wide pH range. [Display omitted] • As-Prepared electrocatalysts exhibited excellent HER activity in a wide pH range. • Structural deformation and lattice strain were constructed by rapid Joule heating. • Ru0 formed by rapid Joule heating inhibited the oxidation of Ru. [ABSTRACT FROM AUTHOR]

Recently, hydrazine borane (HB, N 2 H 4 BH 3) is recognized as an ideal chemical hydrogen storage material due to its high efficiency in storing hydrogen and excellent stability. However, finding an efficient, stable, and low-cost catalyst is still a challenge. In this study, CoPt nanoparticles (NPs) supported on carbon nanotubes (CNTs) are prepared at room temperature. The Co 0. 4 Pt 0.6 /CNTs catalyst exhibits optimal catalytic performance for hydrogen production from HB at ambient conditions, achieving a total turnover frequency (TOF) value of 1525.4 h−1 and 100% H 2 selectivity. The well-dispersed CoPt NPs on CNTs and the synergistic effect between Co and Pt further enhance the decomposition efficiency of HB. This high-performance catalyst has significant implications for the advancement of hydrogen storage materials, particularly in relation to HB. [Display omitted] • Co 0·4 Pt 0.6 /CNTs exhibit high activity and durability for N 2 H 4 BH 3 hydrolysis. • Co 0·4 Pt 0.6 /CNTs provide record turnover frequency value of 1525.4 h−1 for N 2 H 4 BH 3 dehydrogenation at 298 K. • Co 0·4 Pt 0.6 /CNTs achieve 100% H 2 selectivity in N 2 H 4 BH 3 dehydrogenation reaction. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) and their composites are gaining popularity due to their exceptional strength qualities. It is well known that adding CNTs to metal foam composites boosts compressive strength. On the other hand CNT addition is still a costly process due to high cost of the CNTs. This study presents a novel and cost-effective solution by selectively adding CNTs to the structurally weakest regions of aluminum foam materials produced via powder metallurgy, employing a newly developed focused multi-step additive method. The cell borders of aluminum foam are strengthened with multiple spherical layers of CNTs, using a transfer method by initially coating the space holders used at the foaming process. The strength increase effect of this CNT addition method was compared with the widely known aluminum foam production parameters via a 4-parameter design of experiment (DOE) study. Compressive strength values of the samples were evaluated using a constant speed compression test acc. to ISO13314. The compacting pressure, CNT concentration, sintering temperature, and sintering period were chosen as DOE parameters, and 78% of the interactions effecting on final compressive strength could be explained with the model. As a result, it was established that, compared to the other parameters, sintering duration had the highest influence on compressive strength. But besides It has also been shown that adding 0.53% CNT by weight only to the cell border regions increases overall strength by 9%. This weight-strength increase ratio is compared with similar studies in the literature and found to be providing a production cost advantage due to the lower amount of CNT addition requirement for the comparable weight relative strength increase. Focused strength increase method has potential to enable controlled failure of foam materials by selectively strengthening strength critical areas of a component. [ABSTRACT FROM AUTHOR]

Interactions between carbon nanotubes (CNTs) and fluid flows are central to the operation of several emerging nanotechnologies. In this paper, we explore the fluid-structure interaction of CNT micropillars in wall-bounded shear flows, relevant to recently developed microscale wall shear stress sensors. We monitor the deformation of CNT micropillars in channel flow as the flow rate and wall shear stress are gradually varied. We quantify how the micropillars bend at low wall shear stress, and then will commonly tilt abruptly from their base above a threshold wall shear stress, which is attributed to the lower density of the micropillars in this region. Some micropillars are observed to flutter rapidly between a vertical and horizontal position around this threshold wall shear stress, before settling to a tilted position as wall shear stress increases further. Tilted micropillars are found to kink sharply near their base, similar to the observed buckling near the base of CNT micropillars in compression. Upon reducing the flow rate, micropillars are found to fully recover from a near horizontal position to a near vertical position, even with repeated on–off cycling. At sufficiently high wall shear stress, the micropillars were found to detach at the catalyst particle-substrate interface. The mechanical response of CNT micropillars in airflow revealed by this study provides a basis for future development efforts and the accurate simulation of CNT micropillar wall shear stress sensors. [ABSTRACT FROM AUTHOR]

This research examines the analytical investigations for radiating Casson nanofluid models with unsteady convecting flow, which are valued by the order of Caputo fractional derivative (CFD). Ethylene glycol (EG) is used as a base fluid, and graphene oxide (GO) and carbon nanotubes (CNTs) are used as nanoparticles. The problem's leading PDEs are nondimensionalized by applying the proper nondimensional variables. The solutions to the dimensionless governing equations are found by using the Fourier sine and Laplace transformation techniques together. For an enormous study of the problem, graphical illustrations and tables are developed by using MATLAB software programming with the help of Euler inversion. We examine the impact on the fractional heat and momentum equation of the α , Gr, Pr, ϕ , R, β , oscillations. Using the properties of the fluid, important discoveries were made that indicated a number of elements for a number of flow parameters as well as fractional parameters. The thermal profiles are increased for R , ϕ decreased for α at τ = 0. 4 and τ = 1. 4. The velocity profiles are increased for R and Gr decreased for β and ϕ at τ = 0. 4 and 1.4. Different shapes of nanoparticles are performed for ordinary fractional parameters, which are increased for temperature as well as velocity. [ABSTRACT FROM AUTHOR]

Squeezing or squeeze flows have tremendous applications in applied fields, like engineering, biomedical sciences and rheological studies. This paper demonstrates the squeezing flow of kerosene-based nanoliquids between parallelly aligned plates, with a Riga-type fixed lower boundary. The effects of dispersing two types of copper-functionalized carbon nanotubes (CNTs), single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are examined. Using appropriate transformations, a self-similar ordinary differential system is derived from the governing model of partial differential equations and substantial boundary conditions. Using the homotopy analysis method (HAM) and the b v p 4 c package, analytical and numerical estimates are obtained, respectively. For higher values of the squeezing parameter, dimensionless temperature increases, while velocity patterns are upside-down. Moreover, increments in dimensionless parameters representing Riga constituent width, modified Hartmann number, nanoparticle concentration and radiation parameter improve heat transfer rates and thermal boundary layer thickness, however, adversely affect velocity. Despite enhanced friction effects, numerical results show that the Nusselt number increases as nanoparticle loads and radiation parameters increase. This suggests that convection rates are improved over conduction rates. Excellent agreement is found between analytical and numerical evaluations. Apparently, it is noticed that MWCNTs perform better than SWCNTs. [ABSTRACT FROM AUTHOR]

This research leads to carrying out the productivity and the efficiency of the carbon nanotubes (CNTs) that have extensive applications in solar collectors. Due to the superior thermal as well as electrical properties, the use of CNTs has an important contribution to the nanotechnology revolution. Therefore, owing to the aforementioned vital points, this investigation intended to put forth the thermophysical properties of both single and multi-walled CNT nanofluids past a stretching surface. Additionally, an electrically conducting nanofluid flow phenomenon enriches due to the inclusion of dissipation (Ohmic heating) and external heat source/sink. The dimensional form of the three-dimensional fluid flow phenomena is transformed to a non-dimensional form with the use of similarity transformation and further numerical procedure is implemented to solve the nonlinear governing equations. The substantial significance of the characterizing parameters is presented briefly via figures and the comparative analysis with the earlier investigation is deployed through the table. However, the main findings of this study are as follows: A significant attenuation in the shear rate is marked for the enhanced inertial drag but it augments for the augmented values of the magnetization; further, particle concentrations of both the CNTs favor accelerating the fluid momentum as well as temperature distribution. [ABSTRACT FROM AUTHOR]

This study delves into the exploration of hybrid nanofluids within the context of a stretching cylinder, a domain that has captivated numerous researchers owing to its pivotal applications in industrial manufacturing processes, particularly in metal forming and stretch dies. The authors, recognizing the significance of these applications, have introduced a novel heat transfer fluid termed hybrid nanofluid, comprising molybdenum disulfide and carbon nanotubes suspended in the base liquid, water. The investigation focuses on the flow of the hybrid nanofluid within a stretching cylinder, considering various influential factors such as Joule heating, thermal radiation, porous medium, and magnetic field effects. To model this complex problem, we employed modified Navier–Stokes equations. Employing similarity transformations, assumptions, and non-dimensional parameters, the problem was effectively simplified. The MATLAB bvp4c technique, a well-established numerical approach, was then employed to solve the resulting mathematical formulation. Graphical representations are presented to illustrate various aspects of the flow, facilitating a comprehensive understanding of the system. Comparisons are drawn among the flow characteristics of mono nanofluid, and the developed hybrid nanofluid. It is noted from the current analysis that the temperature strength increases with higher values of the magnetic field parameter, curvature parameter, radiation parameter, and Eckert number in both fluid cases. The Nusselt number increases with higher values of Prandtl number and thermal relaxation parameter. The identified patterns in velocity distribution, temperature strength, and fluid behavior provide a valuable foundation for optimizing thermal efficiency in diverse industrial applications. By leveraging the insights gained from this research, manufacturers can make informed decisions to enhance heat transfer processes, particularly in areas such as metal forming and stretch dies. [ABSTRACT FROM AUTHOR]

Highlights The mechanical strength of polylactic acid (PLA) can be improved by carbon fiber (CF) compositing to expand its application in tissue engineering scaffolds. However, the mechanical strength of CF‐reinforced polylactic acid (CFRPLA) composites is compromised due to weak interfacial interaction resulting from the chemically inert surface of CF. In the article, carbon nanotube (CNT) with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent was covered on CF to improve the chemical activity and roughness of the surface of CF, and then the as‐prepared CF‐PCNT were further incorporated into PLA via melt compounding. The yield strength, modulus, and thermal conductivity of PLA/CF‐PCNT were 14.09%, 7.65%, and 5.24% higher than those of PLA/CF, respectively, and the volume resistivity was 99.74% lower at a 10 wt% loading. The enhancement for the mechanical properties of PLA/CF‐PCNT composites could be ascribed to the mechanical locking, hydrogen bonds and covalent bonds between CF and matrix through the interface modulation of CNT and PDDA. This facile and non‐destructive method offers a novel strategy for the modification of CF fillers. CF was modified by PDDA and CNT through a facile and non‐destructive method. The active functional groups and roughness on the surface of CF were increased. The surfaces of CFs were characterized by FT‐IR, Raman spectra, XPS and SEM. The interface was improved by mechanical locking, covalent, and hydrogen bonds. The mechanical strength, electrical and thermal conductivity of composites were improved. [ABSTRACT FROM AUTHOR]

The present work provides a unique insight to reveal the long chain branching (LCB) influence to the nano‐fillers, that is via analyzing the conductivity evolution during the thermal annealing, fast shear flow and melt to solid cooling process. Meanwhile the crystallization behavior is also discussed. A linear polypropylene (PPC) and a long chain branched polypropylene (PPH) are chosen as the two polymer matrices with carbon nanotubes (CNTs) as the nanofillers. During the thermal annealing process, a more obvious growth of electrical conductivity of linear PPC nanocomposites are observed compared with LCB PPH nanocomposites. The harder movement of CNTs inside LCB PPH matrix may be the main reason. This also can be reflected by the conductivity evolution during slow cooling process where a decrease‐then‐increase (DTI) phenomenon is found for PPC/CNTs systems due to the rebuilding of CNTs conductivity network after crystallization. By contrast, this does not happen for PPH/CNTs systems. [ABSTRACT FROM AUTHOR]

The meticulous design of highly efficient indirect electrocatalysts with value‐added conversion properties remains a substantial challenge within the realm of organic catalysis. While polyoxometalates (POMs) serve as crucial active centers in catalytic modeling systems for chemical materials, their exploration in electrocatalytic organic molecular transformations is hindered by kinetic barriers. Therefore, an efficient protocol is established for the synthesis of electrocatalysts utilizing polyoxomolybdates (CuMo6) immobilized on aerogel foams (CMC). The electrical conductivity and electrocatalytic activities of the electrocatalyst (CuMo6/CNT@CMC) can be readily enhanced by adjusting the microenvironment between the CuMo6 and CMC using carbon nanotubes (CNT). Controlled experiments demonstrate that the CuMo6/CNT@CMC electrocatalyst for the oxidation of sulfide achieves an impressive Faradaic Efficiency (FE) exceeding 95% under ambient conditions, while the working potential is markedly lower than that of reported heterogeneous electrocatalysts. Combined experimental and theoretical analyses suggest that the modulated electronic synergistic interaction between the Cu‐assisted Mo sites and CNT within foam favors the appropriate binding of PhCH3S+• intermediates, thereby promoting the selective oxidation of sulfides. This study paves the way for the utilization of polyoxometalate‐based materials with simple synthesis methods for various electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Photodetectors are a key sensing component in enabling emerging technologies. For weak light detection, phototransistors with high responsivity are needed. Furthermore, the ability to fabricate phototransistors using solution processing techniques will enable new form factors, including flexible and large‐area devices. In this work, a novel approach for synthesizing a photosensitive organic/inorganic hybrid semiconducting thin film through solution processing is introduced. The approach involves hierarchical patterning of semiconducting carbon nanotubes (CNTs) with poly(3‐hexylthiophene‐2,5‐dyl) (P3HT) through solution‐phase heterogeneous crystallization. The fabricated hybrid phototransistors are qualified through electrical testing at varied illumination profiles within the visible light range. At a wavelength of 470 nm with an optical excitation power of 0.37 µW cm−2, the device exhibits photoresponsivity of 3.53 × 105 AW−1, surpassing other solution‐processed, non‐lead‐containing devices in the literature. The optical response extends from both photogating (low excitation power) and photon‐induced carrier generation (high excitation power). The detectivity of the device is ≈8.7 × 1010 Jones. The transient response includes a rise time of 100 ms and a fall time of 200 ms which is similar to the metrics of other low‐dimensional photodetectors. These findings highlight the prospects of the solution‐processed P3HT/semi‐CNT hybrid platform for advanced photodetection applications with flexible and large‐area form factors. [ABSTRACT FROM AUTHOR]

As an alternative to thermionic X‐ray generators, cold‐cathode X‐ray tubes are being developed for portable and multichannel tomography. Field emission propagating from needle structures such as carbon nanotubes or Si tips currently dominates related research and development, but various obstacles prevent the widespread of this technology. An old but simple electron emission design is the planar tunnelling cathode using a metal–oxide–semiconductor (MOS) structure, which achieves narrow beam dispersion and low supplying voltage. Directly grown vertical graphene (VG) is employed as the gate electrode of MOS and tests its potential as a new emission source. The emission efficiency of the device is initially ≈1% because of unavoidable fabrication damage during the patterning processes; it drastically improves to >40% after ozone treatment. The resulting emission current obeys the Fowler–Nordheim tunnelling model, and the enhanced emission is attributed to the effective gate thickness reduction by ozone treatment. As a proof‐of‐concept experiment, a clustered array of 2140 cells is integrated into a system that provides mA‐class emission current for X‐ray generation. With pulsed digital excitations, X‐ray imaging of a chest phantom, demonstrating the feasibility of using a VG MOS electron emission source as a new and innovative X‐ray generator is realized. [ABSTRACT FROM AUTHOR]

The chlorine evolution reaction (CER) is a crucial anode reaction in the chlor‐alkali industrial process. Precious metal‐based dimensionally stable anodes (DSA) are commonly used as catalysts for CER but are constrained by their high cost and low selectivity. Herein, a Pt dual singe‐atom catalyst (DSAC) dispersed on fluorine‐doped carbon nanotubes (F‐CNTs) is designed for an efficient and robust CER process. The prepared Pt DSAC demonstrates excellent CER activity with a low overpotential of 21 mV to achieve a current density of 10 mA cm−2 and a remarkable mass activity of 3802.6 A gpt−1 at an overpotential around 30 mV, outperforming those of commercial DSA and Pt single‐atom catalyst. The excellent CER performance of Pt DSAC is attributed to the high atomic utilization and improved intrinsic activity. Notably, introducing fluorine atoms on CNTs increases the oxidation and chlorination resistance of Pt DSAC, and reduces the demetalization ratio of Pt atoms, resulting in excellent long‐term CER stability. Theoretical calculations reveal that several Pt DSAC configurations with optimized first‐shell ligands and interatomic distance display lower energy barriers for Cl intermediates generation and weaker ionic Pt−Cl bond interaction, which are favorable for the CER process. [ABSTRACT FROM AUTHOR]

All‐solid‐state sulfur batteries (ASBs) suffer from electrical and ionic conduction problems due to the insulating sulfur. By comparing three host materials with different structural characteristics, herein, carbon nanotubes (CNTs) decorated with a conductive metal sulfide (CoMoS2@CNT) is demonstrated, designed to host sulfur and exchange both Li‐ions and electrons, effectively. In this hierarchical wire structure, porous CoMoS2 nanosheets form close interfaces with sulfur, and the CNT core directly transfers electrons to the sulfur‐impregnated CoMoS2. Simultaneously, the solid electrolyte positioned on the outer region of the nanowire material ensures facile Li‐ion conduction to the sulfur‐impregnated CoMoS2. An ASB featuring a CoMoS2@CNT host material with a sulfur loading of 3 mg cm−2 exhibits a high‐areal‐capacity of 4.5 mAh cm−2 at a current density of 2.5 mA cm−2, while retaining 79.4% of its initial capacity after 300 cycles. When sulfur is replaced with SeS2 to further reinforce the charge conduction properties, all‐solid‐state SeS2 batteries (ASeS2Bs) with an extremely high‐areal‐capacity of 16.3 mAh cm−2 retain 99.3% of their initial capacities after 60 cycles at 60 °C. This study provides guidelines for the design principles of cathode composites for the ASBs and ASeS2Bs through multiangle comparative analysis. [ABSTRACT FROM AUTHOR]

Exploration for sustainable energy resources is essential to minimize the dependence on fossil fuels and to improve environmental parameters. Here, the possibility of utilizing bio‐waste‐derived electrolytes as an electrical energy resource by placing them across semipermeable membranes prepared through parallel stacking of coir fibers is examined. The nanofluidic membrane (d‐CF‐V) prepared by modifying the inner walls of the bio‐fluidic channels with atomically thin layers of vanadium pentoxide (VO) shows excellent perm‐selectivity (t+ = 0.87, with 1000‐fold concentration difference) and electricity conversion efficiency (≈ 28.2%). With simulated sea and river water, the d‐CF‐V yields output energy up to 2.4 W m−2, similarly with mineral acid bases (0.5 m HCl and 0.01 m NaOH), the d‐CF‐V shows an energy output of 11.8 W m−2. The sun‐dried Garcinia morella (Kuji thekera), and charred peels of Musa balbisiana (banana) are used as sustainable sources of bio‐electrolytes, which in combination with permselective d‐CF‐V yielded a power density of ≈1.4 W m−2. By replacing standard Ag/AgCl electrodes with nanomaterials exhibiting contrasting charge transfer activities, oxidized carbon nanotube membrane (o‐CNT) and polyaniline (PANI) membrane the output voltage is enhanced from –127 to –568 mV and current output is increased from 10.2 to 51.5 µA. [ABSTRACT FROM AUTHOR]

Significant efforts are being made to develop high‐performance battery materials, particularly active materials. However, material‐dependent strategies for increasing energy density face challenges such as raw material costs and supply limitations, reducing their versatility to some extent. In this regard, the development of efficient battery designs can be a universal approach to increasing the energy density of lithium‐ion batteries with relatively low dependence on material properties. Herein, a novel configuration of an electrode‐separator assembly is presented, where the electrode layer is directly coated on the separator, to realize lightweight lithium‐ion batteries by removing heavy current collectors. Even on the hydrophobic separator, a poly(vinyl alcohol) binder enables uniform and scalable coating of aqueous electrode slurries through molecular interactions with the separator surface. Moreover, carbon nanotubes are utilized to reinforce the electronic conduction of the electrode, providing consistent electronic pathways regardless of SEI formation. Furthermore, owing to the superior permeability of liquid electrolytes through this electrode‐separator assembly, a multilayered electrode‐separator assembly can be suggested to further increase energy density when combined with a lithium metal anode. This lithium metal battery can achieve an areal capacity of ≈30 mAh cm−2 and an enhanced energy density of over 20% compared to conventional battery configurations. [ABSTRACT FROM AUTHOR]

MnO2 is commonly used as the cathode material for aqueous zinc‐ion batteries (AZIBs). The strong Coulombic interaction between Zn ions and the MnO2 lattice causes significant lattice distortion and, combined with the Jahn–Teller effect, results in Mn2+ dissolution and structural collapse. While proton intercalation can reduce lattice distortion, it changes the electrolyte pH, producing chemically inert byproducts. These issues greatly affect the reversibility of Zn2+ intercalation/extraction, leading to significant capacity degradation of MnO2. Herein, we propose a novel method to enhance the cycling stability of δ‐MnO2 through selenium doping (Se−MnO2). Our work indicates that varying the selenium doping content can regulate the intercalation ratio of H+ in MnO2, thereby suppressing the formation of ZnMn2O4 by‐products. Se doping mitigates the lattice strain of MnO2 during Zn2+ intercalation/deintercalation by reducing Mn−O octahedral distortion, modifying Mn−O bond length upon Zn2+ insertion, and alleviating Mn dissolution caused by the Jahn–Teller effect. The optimized Se−MnO2 (Se concentration of 0.8 at.%) deposited on carbon nanotube demonstrates a notable capacity of 386 mAh g−1 at 0.1 A g−1, with exceptional long‐term cycle stability, retaining 102 mAh g−1 capacity after 5000 cycles at 3.0 A g−1. [ABSTRACT FROM AUTHOR]

Atomically precise supported nanocluster catalysts (APSNCs), which feature exact atomic composition, well‐defined structures, and unique catalytic properties, offer an exceptional platform for understanding the structure‐performance relationship at the atomic level. However, fabricating APSNCs with precisely controlled and uniform metal atom numbers, as well as maintaining a stable structure, remains a significant challenge due to uncontrollable dispersion and easy aggregation during synthetic and catalytic processes. Herein, we developed an effective ligand engineering strategy to construct a Pt6 nanocluster catalyst stabilized on oxidized carbon nanotubes (Pt6/OCNT). The structural analysis revealed that Pt6 nanoclusters in Pt6/OCNT were fully exposed and exhibited a planar structure. Furthermore, the obtained Pt6/OCNT exhibited outstanding acidic HOR performances with a high mass activity of 18.37 A ⋅ mgpt−1 along with excellent stability during a 24 h constant operation and good CO tolerance, surpassing those of the commercial Pt/C. Density functional theory (DFT) calculations demonstrated that the unique geometric and electronic structures of Pt6 nanoclusters on OCNT altered the hydrogen adsorption energies on catalytic sites and thus lowered the HOR theoretical overpotential. This work presents a new prospect for designing and synthesizing advanced APSNCs for efficient energy electrocatalysis. [ABSTRACT FROM AUTHOR]

High entropy alloy nanoparticles encapsulated into nitrogen-doped carbon nanotubes show superior bifunctionality for the ORR and OER, evidenced by a battery performance of 214 mW cm−2, sustained for 200 h. [ABSTRACT FROM AUTHOR]