Single-walled Carbon Nanotube Networks Research Articles

Laser fabrication of composite layers from biopolymers with branched 3D networks of single-walled carbon nanotubes for cardiovascular implants

A laser technology has been developed for fabricating structures from composite layers based on biopolymers: albumin, collagen, and chitosan with single-walled carbon nanotubes (SWCNT). The structures are intended for cardiovascular devices and tissue-engineered implants. This is evidenced by the results of studies. The composite layers were fabricated due to the phase transition of biopolymers and SWCNT aqueous dispersion under the influence of laser pulses. At the same time branched 3D networks of SWCNT were formed in the biopolymer matrix. The threshold energy fluence of laser pulses was determined (0.032–0.083 J/cm2) at which a bimodal distribution of pores was observed. The calculation of contact resistances between nanotubes at percolation units of 3D networks (20–100 kOhm) was carried out. Composite layers fabricated by laser demonstrated conductivity values that were higher (12.4 S/m) than those for layers by thermostat (4.7 S/m). The maximum hardness of the composite layers with SWCNT (0.01 wt%) by laser was 482 ± 10, 425 ± 10, and 407 ± 15 MPa for albumin, collagen and chitosan, respectively. The hardness of the thermostat layers was less than 100 MPa. The viability of endothelial cells in composite layers was improved. The composite layers ensured a normal level of hemolysis during interaction with erythrocytes.

Effective Doping of Single-Walled Carbon Nanotubes with Polyethyleneimine.

More and more electrically conducting materials are required to sustain the technological progress of civilization. Faced with the performance limits of classical materials, the R&D community has put efforts into developing nanomaterials, which can offer sufficiently high operational parameters. In this work, single-walled carbon nanotubes (SWCNTs) were doped with polyethyleneimine (PEI) to create such material. The results show that it is most fruitful to combine these components at the synthesis stage of an SWCNT network from their dispersion. In this case, the electrical conductivity of the material is boosted from 249 ± 21 S/cm to 1301 ± 56 S/cm straightforwardly and effectively.

Charge and Thermoelectric Transport in Polymer-Sorted Semiconducting Single-Walled Carbon Nanotube Networks.

Understanding the charge transport mechanisms in chirality-selected single-walled carbon nanotube (SWCNT) networks and the influence of network parameters is essential for further advances of their optoelectronic and thermoelectric applications. Here, we report on charge density and temperature-dependent field-effect mobility and on-chip field-effect-modulated Seebeck coefficient measurements of polymer-sorted monochiral small-diameter (6,5) (0.76 nm) and mixed large-diameter SWCNT (1.17-1.55 nm) networks (plasma torch nanotubes, RN) with different network densities and length distributions. All untreated networks display balanced ambipolar transport and electron-hole symmetric Seebeck coefficients. We show that charge and thermoelectric transport in SWCNT networks can be modeled by the Boltzmann transport formalism, incorporating transport in heterogeneous media and fluctuation-induced tunneling. Considering the diameter-dependent one-dimensional density of states (DoS) of the SWCNTs composing the network, we can simulate the charge density and temperature-dependent Seebeck coefficients. Our simulations suggest that scattering in these networks cannot be described as simple one-dimensional acoustic and optical phonon scattering as for single SWCNTs. Instead the relaxation time is inversely proportional to energy (τ ∝ (E - EC)s, s = -1, EC being the energy of the first van Hove singularity), presumably pointing toward the more two-dimensional character of scattering events and the necessity to include scattering at the SWCNT junctions. Finally, our observation of higher power factors in trap-free, 1,2,4,5-tetrakis(tetramethylguanidino)benzene-treated (6,5) networks than in the RN networks emphasizes the importance of chirality selection to tune the width of the DoS. To benefit from both higher intrinsic mobilities and a large thermally accessible DoS, we propose trap-free, narrow DoS distribution, large-diameter SWCNT networks for both electronic and thermoelectric applications.

Ni@Ni3C Nanochain-SWCNT Composite with Comparable Electrocatalysis of Benchmark Pt/C for Hydrogen Evolution Reaction

Developing robust and low-cost electrocatalysts for efficient hydrogen evolution reaction (HER) through facile methods is of great significance to the energy and environment sustainability. Herein, a simple one-pot solvothermal method has been developed to synthesize a hybrid material of nickel@nickel carbide (Ni@Ni3C) nanochain embedded in a network of single-walled carbon nanotubes (SWCNTs). The electrochemical experiments indicate that the composite of Ni@Ni3C-SWCNTs has the HER electrocatalytic performance comparable to that of Pt/C in an acidic medium (0.5 M H2SO4). The overpotential to reach a current density of 10 mA cm−2 in 0.5 M H2SO4 is only −74 mV with a Tafel slope of 46.9 mV dec−1. Compared to Ni@Ni3C in the absence of SWCNTs, the enhanced HER performance of Ni@Ni3C-SWCNTs can be attributed to the increased intrinsic activity, improved electronic conductivity, and the electron coupling effect between Ni@Ni3C and SWCNTs. The Ni@Ni3C-SWCNTs composites also show high stability at the overpotential of −0.2 V for 24 h. This work provides guidance for the synthesis of high-performance non-precious metal electrocatalysts for HER.

Improved supercapacitors by implanting ultra-long single-walled carbon nanotubes into manganese oxide domains

Ultra-long single-walled carbon nanotubes (SWCNTs) are implanted into thicker manganese oxide (MnO2) domains for enhancing the ultimate energy density of the MnO2 based supercapacitors. The implanted SWCNTs form a nano-meshed jungle-gym wherein the MnO2 domains are densely packed. Functioned as templates, MnO2 domains have been divided into nano-sized particles during the electrochemical deposition of the thicker MnO2 domains. Functioned as conductive paths, electrons transferred under lower resistances via the SWCNT networks during the charge/discharge. The ultimate thickness of the resultant SWCNT-MnO2, which is established on the cell-walls of nickel foams (NF; NF served as current collectors) can reach to 13.3 μm while the electrochemical performance of the SWCNT-MnO2@NF electrode remains excellent (1898 mF cm−2 capacitances; 101.9% specific capacitance retention ratios, after 10,000 times of charge/discharge). We also assembled asymmetric supercapacitor cells and obtained high energy densities (734.1 μWh cm−2) and high power densities (18.47 mW cm−2 at 277.1 μWh cm−2). Electrochemical data are analysed based on Dunn's method, new insights into the capacitive behaviours of the SWCNT-MnO2@NF are observed.

No2 Sensing with SWCNT Decorated by Nanoparticles in Temperature Pulsed Mode: Modeling and Characterization.

In this paper, NO2 sensing by means of single-wall carbon nanotubes (SWCNT) networks, decorated with nanoparticles of TiO2 and Au, is proposed. In particular, it is shown that the performance of these materials can be enhanced using pulsed temperature mode. This sensing strategy effectiveness is theoretically and experimentally assessed. In this paper, in fact, a dynamic model for conductive gas sensors formed by networks of nanowires, considering the junctions between different wires as the main contribution to sensor conductance, and in the presence of the target gas, is presented and validated. The model accounts for variable temperature and gas concentration and sheds some light on the mechanisms leading to the sensor response improvement related to temperature pulsed working mode. It is also shown how the addition of a different material can be modeled through different surface adsorption kinetics.

Dense Assembly of Finely Patterned Semiconducting Single-Walled Carbon Nanotubes via a Selective Transfer Method of Nanotube-Attracting Layers.

Development of technology for assembled single-walled carbon nanotube (SWCNT) film with the fine resolution is an essential technique for penetrating practical electronic applications. A promising approach is the assembly method by adding a chemical-functionalizing substrate to enhance affinity between the SWCNTs and the substrate. However, the various introduced approaches for solution-based assembly have suffered from low SWCNT deposition selectivity or low SWCNT deposition density. Herein, we demonstrated a facile method for selectively assembling semiconducting SWCNT network on the substrate. The substrate was prepared via a transfer printing of a poly-l-lysine (PLL)-coated poly(dimethylsiloxane) (PDMS) stamp. The thermal-assisted transfer method enabled an ultrafine PLL pattern (≤4 μm) and a high transfer yield (96.5%) by only one-time stamping without a change of the SWCNT-attracting nature. So, semiconducting SWCNTs were deposited on the patterned regions selectively and precisely. The benefit of the patterned semiconducting SWCNTs was lowering leakage current and turn-on voltage in the transfer characteristics by suppressing attachment of unnecessary SWCNT network. They showed excellent electrical performance, a log10(Ion/Ioff) ratio of 4.76, and an average value of linear field-effect mobility of 7.56 cm2/(V s). This research provides a simple but high-quality assembling technique of semiconducting SWCNTs, thereby improving the feasibility of solution-processed SWCNT-TFTs.

P‐189: Late‐News‐Poster: In‐situ Selective UV‐O3 based Facile Patterning Method of Random SWCNT Networks for Solution‐processed SWCNT TFT and Circuit Application

We introduce in‐situ ultraviolet ozone(UVO) patterning technique to selectively attach the Poly‐L‐Lysine(PLL) material, which ultimately patterns the solution‐processed and directlydeposited random networks of single‐walled carbon nanotube(SWCNT). Furthermore, we demonstrated feasibility and applicability of our technique by implementing 16 devices on SiO2 substrate and all‐solution‐processed logic inverter circuit at organic dielectric.

A flexible thermoelectric device based on a Bi2Te3-carbon nanotube hybrid

Thermoelectric (TE) materials and devices have attracted great attention due to their ability to convert waste heat to electrical power and active cooling. However, the conventional bulk TE materials are inorganic semiconductors with inherent brittleness and rigidity. They cannot closely contact curved heat sources and sinks, which limits their application in modern electronics. It remains a big challenge to fabricate high-performance TE materials and devices with good flexibility. Here, we report a flexible TE device comprised of a single wall carbon nanotube (SWCNT) network and (000l)-textured Bi2Te3 nanocrystals prepared by a magnetron sputtering technique. The unique Bi2Te3-SWCNT hybrid structure has a TE figure of merit (ZT) value of ∼0.23 at ∼330 K. A prototype TE device made of this hybrid gives a maximum output power density of ∼0.93 mW cm−2 under a temperature difference of 25 K at ambient temperature and shows good flexibility under bending. Our results open up a new way to the development of flexible TEs and their application in self-powered portable devices.

Freestanding Potassium Vanadate/Carbon Nanotube Films for Ultralong-Life Aqueous Zinc-Ion Batteries.

Among various energy storage devices, aqueous zinc-ion batteries (ZIBs) have captured great attention due to their high safety and low cost. One of the most promising cathodes of aqueous ZIBs is layered vanadium-based compounds. However, they often suffer from the capacity decaying during cycling. Herein, we prepared KV3O8·0.75H2O (KVO) and further incorporated it into a single-walled carbon nanotube (SWCNT) network, achieving freestanding KVO/SWCNT composite films. The KVO/SWCNT cathodes exhibit a Zn2+/H+ insertion/extraction mechanism, resulting in fast kinetics of ion transfer. In addition, the KVO/SWCNT composite films possess a segregated network structure, which offers the fast kinetics of electron transfer and guarantees an intimate contact between KVO and SWCNTs during cycling. As a result, the resultant batteries deliver a high capacity of 379 mAh g-1, excellent rate capability, and an ultralong cycle life up to 10,000 cycles with a high capacity retention of 91%. In addition, owing to the high conductivity and flexibility of KVO/SWCNT films, flexible soft-packaged ZIBs based on KVO/SWCNT film cathodes were assembled and displayed stable electrochemical performance at different bending states.

Fabrication of Carbon Nanotube Thin Films for Flexible Transistors by Using a Cross-Linked Amine Polymer.

Owing to their remarkable properties, single-walled carbon nanotube thin-film transistors (SWCNT-TFTs) are expected to be used in various flexible electronics applications. To fabricate SWCNT channel layers for TFTs, solution-based film formation on a self-assembled monolayer (SAM) covered with amino groups is commonly used. However, this method uses highly oxidized surfaces, which is not suitable for flexible polymeric substrates. In this work, a solution-based SWCNT film fabrication using methoxycarbonyl polyallylamine (Moc-PAA) is reported. The NH2 -terminated surface of the cross-linked Moc-PAA layer enables the formation of highly dense and uniform SWCNT networks on both rigid and flexible substrates. TFTs that use the fabricated SWCNT thin film exhibited excellent performance with small variations. The presented simple method to access SWCNT thin film accelerates the realization of flexible nanoelectronics.

Cascade Reaction-Based Chemiresistive Array for Ethylene Sensing.

Chemiresistive sensors, which are based on semiconducting materials, offer real-time monitoring of environment. However, detection of nonpolar chemical substances is often challenging because of the weakness of the doping effect. Herein, we report a concept of combining a cascade reaction (CR) and a chemiresistive sensor array for sensitive and selective detection of a target analyte (herein, ethylene in air). Ethylene was converted to acetaldehyde through a Pd-catalyzed heterogeneous Wacker reaction at 40 °C, followed by condensation with hydroxylamine hydrochloride to emit HCl vapor. HCl works as a strong dopant for single-walled carbon nanotubes (SWCNTs), enabling the main sensor to detect ethylene with excellent sensitivity (10.9% ppm-1) and limit of detection (0.2 ppm) in 5 min. False responses that occur in the main sensor are easily discriminated by reference sensors that partially employ CR. Moreover, though the sensor monitors the variation of normalized electric resistance (ΔR/R0) in the SWCNT network, temporary deactivation of CR yields a sensor system that does not require analyte-free air for a baseline correction (i.e., estimation of R0) and recovery of response. The concept presented here is generally applicable and offers a solution for several issues that are inherently present in chemiresistive sensing systems.

Charge Modulation Spectroscopy of Pristine and sp3-Functionalized Single-Walled Carbon Nanotube Networks

The controlled decoration of single-walled carbon nanotubes (SWCNTs) with luminescent sp3 defects has emerged as a powerful approach to enhance their usually low photoluminescence (PL) quantum yields and achieve tuneable emission across the near-infrared even for polymer-wrapped nanotubes [ACS Nano 2019, 13, 9259]. However, their application in optoelectronic devices requires a detailed understanding of the impact of sp3 functionalization on their electrical performance. While isolated sp3 defects on single SWCNTs increase the resistance by a few kΩ, the effect of functionalization on charge transport in networks of semiconducting SWCNTs remains unexplored. Charge modulation spectroscopy is ideally suited to probe the mobile charge carriers in SWCNT networks and has previously corroborated the notion that charge accumulation and transport in mixed SWCNT networks is highly chirality- and gate voltage-dependent. Here, we use charge-modulated PL (CMPL) spectroscopy to study the current pathways in field-effect transistors based on networks of pristine and functionalized (6,5) SWCNTs. We find that the defects are very efficiently sampled by mobile carriers and consequently, sp3-functionalized SWCNTs actively participate in the charge transport in these networks. In combination with voltage-dependent PL and electroluminescence measurements, our CMPL method provides fundamental insights into the interaction of charge carriers with sp3 defects in SWCNT thin film devices.Fig. 1: Schematic of the charge modulation PL spectroscopy setup (left) and CMPL spectra of pristine and functionalized (6,5) SWCNT network field-effect transistors (right). Figure 1

Single-Wall Carbon Nanotube Uptake Based on Energy-Dependence and Metastatic Potential of Epithelial Cells Motivates Carrier Delivery of Drugs for Targeting Cancer

Cancer cells have altered metabolic activity that can be appropriated for delivery of drugs. Rapidly proliferating cancer cells internalize a high amount of protein-dispersed single-wall carbon nanotubes (SWCNTs) with increased endocytosis from deprivation of metabolic fuels, overexpression and increased recycling of membrane receptors, and mechanosensitivity. Differential uptake of protein-dispersed SWCNTs in various cell types have been reported previously, demonstrating that SWCNT uptake highly depends on uptake pathway and cell metabolism. However, there is still gap in understanding how metastatic potential and cell metabolism can differentiate SWCNT uptake and delivery of drugs in a type of cells. In this work, we present uptake and efficacy of SWCNTs/drug/protein complexes in three different epithelial cell lines, NRK-52E, HeLa, and Hs 578T, that present different metabolic levels from their metastatic potentials. We first create SWCNTs/drug/protein complexes with doxorubicin, a common model cancer drug, and bovine serum albumin (BSA), a model protein that has been extensively studied with SWCNT, using a previously developed unique drug loading system using stepwise assembly on SWCNT networks. The result presented that the cells takes up SWCNTs differently in accordance to their metabolic activity, where Hs 578T cells, with the highest metastatic potential and metabolism, take up ~ 10× more nanotubes compared to an epithelial monolayer of NRK-52E cells. Extent of reduction in cell viability from the delivered drugs were in line with the amount of SWCNT uptake. Our work provides further understanding of differential uptake of protein-dispersed SWCNTs with respect to metabolism and energy requirement of the cells. This suggests that protein-dispersed SWCNTs could preferentially target and deliver drugs to cancer cells in a local area with a combination of normal epithelial cells and cancerous cells.

Controlled, Stepwise Assembly of Highly Potent Drugs on Single-Wall Carbon Nanotubes

To utilize single-wall carbon nanotubes (SWCNTs) for biomedical applications, individual dispersion and coating of SWCNTs with biocompatible molecules are important to avoid triggering cytotoxicity and increase their stability in serum-containing media. One of the common methods for producing SWCNT-based drug delivery is to individually disperse SWCNTs in aqueous solutions with various biocompatible molecules such as DNA, biopolymers, and proteins, followed by attachment of drugs and targeting moieties to the biologically dispersed nanotubes. Another approach that is less frequently used involves attaching drugs to biocompatible molecules prior to dispersing SWCNTs in a solution. Unfortunately, both approaches suffer from low SWCNT dispersion yield and lack adequate control of drug loading process, especially if the drugs are highly hydrophobic. In this talk, we present an extremely facile schema to generate SWCNT-based drug delivery systems via a controlled, stepwise assembly of drugs and biocompatible molecules on preformed SWCNT networks. We first created a three-dimensional freestanding network of SWCNTs in either aqueous or non-aqueous solvents to facilitate loading of drugs; many potent drugs are only soluble in non-aqueous solvents. SWCNTs in freestanding networks were then coated with drugs such as doxorubicin, which is a common model drug used for characterization of drug loading and release processes owing to its optical properties, and paclitaxel, which is a model drug representing highly lipophilic drugs. Drug-coated SWCNT networks were coated with proteins, such as albumins, followed by dispersing in water via gentle sonication with almost no loss of SWCNT dispersion yield. Optical characterization and imaging have shown that SWCNTs/drug/protein complexes are highly individualized in solution and readily internalized by cells upon exposure. The loaded drugs were efficiently released upon internalization and displayed larger reduction in cell viability compared to free drugs. Further, to demonstrate robustness of our approach and to assist with drug release, we coated SWCNTs with biocompatible polymers prior to decorating with drugs to serve as a sacrificial yet assistive layer. The polymer coating did not alter SWCNT dispersion and drug loading significantly and allowed for faster release of drugs upon internalization in the cells. Overall, the proposed method allows for precisely controlled, stepwise assembly of SWCNTs with any drug and biomolecule combinations and could be further developed for multifunctional drug delivery platform utilizing SWCNTs.

(Invited) Carbon Nanotube Electronic Ratchets

Electronic ratchets are recently demonstrated thin-film semiconductor devices with the ability to harvest energy from high-frequency signals or electrical noise. The state-of-the-art electronic ratchets have been fabricated from doped conjugated polymers, but the device performance is limited by the low charge-carrier mobility and relatively poor electrical conductivity. Enriched semiconducting single-walled carbon nanotube (s-SWCNT) networks represent an attractive alternative to conjugated polymers, since they are easy to dope and exhibit good charge-carrier transport.While the electronic ratchet device is based on a simple field-effect transistor architecture, it requires the generation of asymmetry within the transistor channel. In this presentation, we will outline the approaches employed to control the charge-carrier doping profile to create this asymmetry. We will subsequently discuss the performance of these carbon nanotube electronic ratchets and make a comparison with their conjugated polymer counterparts.

(Invited) Engineering Single Wall Carbon Nanotubes for Sub-Cellular Drug Delivery

Single wall carbon nanotubes (SWCNTs) have been rigorously studied and engineered for a myriad of applications including drug delivery due to their unique, desirable properties. Since SWCNTs bundle in aqueous media and the bundling substantially diminishes their desirable properties along with inducing cytotoxicity, strategies to disperse individually SWCNTs with therapeutic molecules and biologic excipients have been heavily investigated. However, a handful of studies has been performed to understand the interactions between therapeutic molecules and excipients with SWCNT interface as well as the mechanism of intracellular release for therapeutic effects. Additionally, little attention has been paid to how cell type and cell metabolic activity level influence internalization of SWCNTs with different lengths. In this talk, I will discuss cell type, cell metabolic activity, and SWCNT length dependent cellular processing of SWCNTs dispersed with diverse biocompatible dispersing agents. Our results demonstrate that proper choice of dispersing agent can allow for interaction with F-actin, accumulation in the endoplasmic reticulum for eventual expulsion, or accumulation in cell nucleus. Further, macrophages with relatively high cell metabolic activity level compared to other cell types such as fibroblasts have shown to internalize significantly higher amount of SWCNTs per cell. The total mass of SWCNTs internalized per cell increases with a decrease in SWCNT length. Lastly, I will discuss our recent effort to create a ternary complex of SWCNTs, drug, and protein for intracellular delivery and release of model drugs. To overcome the limitation of the existing methods being only plausible for model drugs that are soluble in aqueous solutions, we developed a facile schema to assemble stepwise various combinations of therapeutic molecules and excipients on SWCNTs in different solvents using a preformed SWCNT network. These ternary complexes allow dialing in delivery of therapeutic molecules and excipients to achieve desired cell viability reduction. These findings allow for the development of new SWCNT-based biological applications as they establish important parameters of biomolecule adsorption on SWCNTs, SWCNT internalization and subcellular processing, which are crucial for applications ranging from drug delivery to cell type-specific modulation.

Quantitative trace level voltammetry in the presence of electrode fouling agents: Comparison of single-walled carbon nanotube network electrodes and screen-printed carbon electrodes

Single walled carbon nanotube (SWNT) network electrodes, in which a planar arrangement of SWNTs on an inert surface serve as a working electrode for voltammetry, offer considerable attributes for electroanalysis. Here, the effect of SWNT network density on the trace voltammetric analysis of a water-soluble ferrocene derivative (FcCOOH) is investigated in the presence of polyethylene glycol (PEG) or albumin, species that can foul (block) an electrode via adsorption. Fc-based analytes typically find use in redox labelling or redox shuttling, point-of-care electrochemical detection devices. Comparison is made between SWNT electrodes, grown by catalyzed chemical vapour deposition at three different surface coverages, 5, ~20 and ~30 μmSWNT μm-2, and commercial screen-printed carbon electrodes (SPCEs). In the presence of PEG (8% 2 K), for cyclic voltammetry, the lowest detectable concentration decreases as SWNT network density decreases. However, when employing differential pulse voltammetry, all three networks show a 1 nM FcCOOH limit of detection, three orders of magnitude smaller than achievable with SPCEs. This is attributed to the low capacitance of the SWNTs and absence of amorphous carbon structures which can contribute a pseudo-capacitive response. For both polyethylene glycol (PEG) and albumin (4%), repeat cycling shows the higher density SWNT network electrodes (≥20 μmSWNT μm-2) are far less susceptible to electrode fouling. Toward practical devices, a three-electrode chip, similar in design to that used in SPCEs, but using high density SWNT network electrodes, is also demonstrated to have impressive detection sensitivity for FcCOOH (nM level) in PEG solutions. The simplicity and practicality of the design widens the potential applications of these ultra-sensitive diagnostic tools based on planar network SWNTs.

Three-dimensional, millimeter-scale semiconducting SWCNT aerogels for highly sensitive ozone detection

Semiconducting frameworks possessing porous structure are promising platforms for the detection of hazardous gas molecules. In this study, we propose a facile route to fabricate millimeter-scale, three-dimensional semiconducting SWCNT (s-SWCNT) aerogels and demonstrate deactivation of the co-existing metallic SWCNT (m-SWCNT) network via electrical breakdown process. In particular, the on-off ratio of the modulated semiconducting aerogel after the electrical breakdown process was 205, which is an increase of 18.9 times over that before the process. The modulated semiconducting SWCNT aerogels with a large specific surface area (∼1270 m2 g−1) demonstrated their applicability for highly sensitive ppb-level ozone detection. The modulated semiconducting networks led to a 1310 % increase in the magnitude of response to 30-ppb ozone gas injection compared with that of pristine SWCNT aerogels. Furthermore, the prepared aerogels could detect 3 ppb of ozone within 40 s and retain stable reversible ozone detection for 200 cyclic operations over 100 h. Thus, the proposed semiconducting SWCNT aerogels are a promising candidate for highly sensitive environmental gas sensors.

Monolayer carbon-encapsulated Mo-doped Ni nanoparticles anchored on single-wall carbon nanotube film for total water splitting

Electrochemical water splitting is regarded as a sustainable and cost-effective route for the production of hydrogen. However, the high-cost and poor stability of traditional rare-earth metal-based electrocatalysts make it difficult to yield hydrogen economically. Here, we report an efficient and durable film electrocatalyst of N-doped monolayer carbon encapsulated Mo-doped ultrafine Ni nanoparticles anchored on single-wall carbon nanotube network (NMoNi/SWCNT) for total water splitting in an alkaline solution. The single layer carbon prevents oxidation of encapsulated Ni and Mo species and facilitates desired electronic structure modulation to achieve a high catalytic activity. Hence, the freestanding NMoNi/SWCNT film catalyst shows low overpotentials of 255 mV and 130 mV to attain a current density of 10 mA cm−2 for oxygen evolution reaction and hydrogen evolution reaction, respectively, with a good stability. More importantly, the NMoNi/SWCNT film only requires a potential of 1.6 V to reach a current density of 20 mA cm−2 when employed as both anode and cathode for a total water splitting.