Showing papers on "Nanotube published in 2020"

Aligned, high-density semiconducting carbon nanotube arrays for high-performance electronics.

Abstract: Single-walled carbon nanotubes (CNTs) may enable the fabrication of integrated circuits smaller than 10 nanometers, but this would require scalable production of dense and electronically pure semiconducting nanotube arrays on wafers. We developed a multiple dispersion and sorting process that resulted in extremely high semiconducting purity and a dimension-limited self-alignment (DLSA) procedure for preparing well-aligned CNT arrays (within alignment of 9 degrees) with a tunable density of 100 to 200 CNTs per micrometer on a 10-centimeter silicon wafer. Top-gate field-effect transistors (FETs) fabricated on the CNT array show better performance than that of commercial silicon metal oxide-semiconductor FETs with similar gate length, in particular an on-state current of 1.3 milliamperes per micrometer and a recorded transconductance of 0.9 millisiemens per micrometer for a power supply of 1 volt, while maintaining a low room-temperature subthreshold swing of 8 gigahertz.

Construction of core-shell heterojunction regulating α-Fe2O3 layer on CeO2 nanotube arrays enables highly efficient Z-scheme photoelectrocatalysis

Abstract: Designing direct Z-scheme photocatalytic systems with core-shell architecture is crucial for effective charge separation towards sustainable photocatalysis. Herein, the core-shell heterojunction photocatalyst consisting of α-Fe2O3 nanoparticle layers encapsulating CeO2 nanotube arrays (Ce@Fe) was successfully synthesized through a simple and feasible strategy. The Ce@Fe heterojunctions exhibit the enhanced solar light scattering and absorption performance from 380 nm to 490 nm. The formed direct Z-scheme band structure between CeO2 and α-Fe2O3 further promotes the efficiency of carrier separation and transfer, and the core-shell nanotube array structure provides high specific surface area for antibiotic adsorption and enhanced light scattering, significantly improving the photoelectrocatalytic activity. Impressively, the unique photoelectrode achieves the highest pollutant removal efficiency of 88.6% for photoelectrocatalytic tetracycline degradation at 1 h under full light irradiation, and affords superior stability and strong alkaline resistance, which is expected to photoelectrocatalytic degrade antibiotics with high efficiency and environmental protection in harsh environment. Furthermore, the novel photoelectrocatalytic mechanism involving transfer behaviors of charge carriers, generation of reactive species, degradation intermediate products of tetracycline can be adopted after growing α-Fe2O3 layers onto CeO2 nanotube arrays, in accordance with direct Z-scheme mechanism.

One-dimensional van der Waals heterostructures.

Abstract: We present the experimental synthesis of one-dimensional (1D) van der Waals heterostructures, a class of materials where different atomic layers are coaxially stacked. We demonstrate the growth of single-crystal layers of hexagonal boron nitride (BN) and molybdenum disulfide (MoS2) crystals on single-walled carbon nanotubes (SWCNTs). For the latter, larger-diameter nanotubes that overcome strain effect were more readily synthesized. We also report a 5-nanometer-diameter heterostructure consisting of an inner SWCNT, a middle three-layer BN nanotube, and an outer MoS2 nanotube. Electron diffraction verifies that all shells in the heterostructures are single crystals. This work suggests that all of the materials in the current 2D library could be rolled into their 1D counterparts and a plethora of function-designable 1D heterostructures could be realized.

Rational design of core-shell Co@C nanotubes towards lightweight and high-efficiency microwave absorption

Abstract: Rationally engineering on nanostructure of electromagnetic absorbers provides massive potential for eliminating the pollution caused by electromagnetic radiation. In this work, a series of core-shell Co@C nanotubes were produced via facile pyrolysis of cobalt carbonate hydroxide hydrate/dopamine precursor. Thanks to the well introduction of core-shell and nanotube structure, Co@C composite shows more superior microwave absorption than pristine Co nanoparticles. The unique microstructure provides abundant heterostructures and conductive paths to induce interfacial polarization and conductive loss for boosting dielectric loss. Through regulating the graphitization layer of C shell, the dielectric property could be further enhanced. Coupled with the favorable magnetic loss from the embedded Co nanoparticles, the products exhibit an optimal absorption intensity of −48 dB under low filler content of 30%. And effective absorption frequency bandwidth is up to 5.2 GHz at small thickness of 1.8 mm. Such excellent achievements demonstrate that the core-shell Co@C nanotube composites can be applied as a promising candidate for lightweight and thin electromagnetic absorption.

Fabrication of carbon nanotube field-effect transistors in commercial silicon manufacturing facilities

Abstract: Carbon nanotube field-effect transistors (CNFETs) are a promising nanotechnology for the development of energy-efficient computing. Despite rapid progress, CNFETs have only been fabricated in academic or research laboratories. A critical challenge in transferring this technology to commercial manufacturing facilities is developing a suitable method for depositing nanotubes uniformly over industry-standard large-area substrates. Such a deposition method needs to be manufacturable, compatible with today’s silicon-based technologies, and provide a path to achieving systems with energy efficiency benefits over silicon. Here, we show that a deposition technique in which the substrate is submerged within a nanotube solution can address these challenges and can allow CNFETs to be fabricated within industrial facilities. By elucidating the mechanisms driving nanotube deposition, we develop process modifications to standard solution-based methods that significantly improve throughput, accelerating the deposition process by more than 1,100 times, while simultaneously reducing cost. This allows us to fabricate CNFETs in a commercial silicon manufacturing facility and high-volume semiconductor foundry. We demonstrate uniform and reproducible CNFET fabrication across industry-standard 200 mm wafers, employing the same equipment currently being used to fabricate silicon product wafers. Using a solution-based deposition technique, carbon nanotube field-effect transistors can be fabricated in a commercial silicon manufacturing facility and a high-volume commercial foundry, demonstrating uniform and reproducible transistor fabrication across industry-standard 200 mm wafers.

Maximizing ion accessibility in MXene-knotted carbon nanotube composite electrodes for high-rate electrochemical energy storage.

Abstract: Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. In particular, the kinetics of ion transport in organic electrolytes is slow, especially at low operating temperatures. Herein, we report a new type of MXene-carbon nanotube (CNT) composite electrode that maximizes ion accessibility resulting in exceptional rate performance at low temperatures. The improved ion transport at low temperatures is made possible by breaking the conventional horizontal alignment of the two-dimensional layers of the MXene Ti3C2 by using specially designed knotted CNTs. The large, knot-like structures in the knotted CNTs prevent the usual restacking of the Ti3C2 flakes and create fast ion transport pathways. The MXene-knotted CNT composite electrodes achieve high capacitance (up to 130 F g−1 (276 F cm−3)) in organic electrolytes with high capacitance retention over a wide scan rate range of 10 mV s−1 to 10 V s−1. This study is also the first report utilizing MXene-based supercapacitors at low temperatures (down to −60 °C). Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. Here, the authors report a new type of MXene-carbon nanotube composite electrode that maximizes ion accessibility, resulting in high rate performance at low temperatures.

Hierarchical Cu2S@NiCo-LDH double-shelled nanotube arrays with enhanced electrochemical performance for hybrid supercapacitors

Abstract: Hierarchical nanotube arrays with complex shell structures are attractive for applications in electrode materials for effectively boosted electrochemical performance, but the construction of such delicate architectures with excellent electrochemical performance is very challenging. Herein, double-shelled nanotube arrays of hierarchical Cu2S@nickel–cobalt layered double hydroxide (Cu2S@NiCo-LDH DSNAs) are synthesized on a Cu foam (CF) substrate with a sequential multi-step strategy, and an integrated electrode is constructed with the nanostructured material. Benefiting from the unique hollow structure and the sophisticated assembly of different nano-sized subunits, the as-prepared hierarchical Cu2S@NiCo-LDH DSNA electrode exhibits excellent electrochemical performances with a high mass loading of 5.0 mg cm−2, including a high specific capacity of 2.8 mA h cm−2 (20.4 F cm−2, 555.6 mA h g−1) at 4 mA cm−2 and remarkable rate capability with 87% capacity retention at 40 mA cm−2. Furthermore, a quasi-solid-state hybrid supercapacitor (HSC) is assembled with the Cu2S@NiCo-LDH DSNAs and metal–organic framework (MOF)-derived nanoporous carbon (NPC) as the electrodes, exhibiting a high energy density of 1.67 mW h cm−2 at the power density of 4.25 mW cm−2.

Assembled 3D MOF on 2D Nanosheets for Self-boosting Catalytic Synthesis of N-doped Carbon Nanotube Encapsulated Metallic Co Electrocatalysts for Overall Water Splitting

Abstract: A binder-free electrode with metallic Co embedded in N-doped carbon nanotube array (Co@N-CNT) was fabricated via an electrodeposition, stereoscopic assembly and self-boosting catalytic pyrolysis. Specifically, directed-eletrodeposition vertical growth of Co(OH)2-nanosheet serves as the structure inducer to offer abundant sites for ZIF-67 growth, and melamine is selected as an initiator for orientated growth of N-CNTs. As an integrative non-noble electrocatalyst for water splitting, it requires only 1.58 V to achieve 30 mA cm−2 in an alkali-electrolyzer. The remarkable electrochemical performance is mainly attributed to the unique 3D hierarchical tubular structure and the synergistic effect of each chemical compositions, which provide amount of accessible active sites, accelerate the diffusion of electron/electrolyte, and improve the electrical conductivity, hydrophilicity and structural stability. The electro-catalytic splitting water mechanism was further explored by density functional theory. This universal method can be extensively applied to fabricate well-defined monometal or bimetal encapsulated into N-CNTs for various electrochemical applications.

Carbon nanotube filter functionalized with iron oxychloride for flow-through electro-Fenton

Abstract: Electro-Fenton is a promising advanced oxidation process for the treatment of emerging contaminants from water bodies. Here, we developed a robust and affordable flow-through electro-Fenton process to degrade antibiotic tetracycline. The key component of this technology is an electroactive and porous carbon nanotube filter functionalized with FeOCl. These nanoscale FeOCl significantly promoted the generation of HO• by facilitating efficient cycling of Fe3+/Fe2+. Electrochemical filtration of 0.04 mM tetracycline at −0.8 V vs. Ag/AgCl and a flow rate of 1.5 mL min−1 resulted in an oxidative flux of 5.32 ± 0.41 mmol h−1 m−2. Relative to conventional batch reactor, the proposed system showed enhanced tetracycline degradation kinetics because of the convection-enhanced mass transport. The underlying working mechanism of the system was proposed based on various advanced assessments and density functional theory calculations. This study should offer new insights about the rational design of continuous-flow systems towards efficient removal of various contaminants.

Oxygen vacancy self-doped black TiO2 nanotube arrays by aluminothermic reduction for photocatalytic CO2 reduction under visible light illumination

Abstract: In this work, black titania nanotube arrays (B-TiO2NTAs) were prepared by aluminothermic reduction of anodized TiO2-NTAs. It was found that the oxygen partial pressure atmicro-region of TiO2-NTAs surfacewas critical for the creation of black TiO2 NTAs. The oxygen vacancies in the prepared B-TiO2 NTAs induced new defect energy levels in the band gap of TiO2, which reduced the band gap and broadened their visible light absorption. Furthermore, the oxygen vacancies could also act as the catalytic sites and accelerate surface reactions for the photocatalytic reduction of CO2 to CO, which also was proved by isotope experiment. Especially, B-TiO2 NTAs annealed at 600℃ showed an excellent photocatalytic CO2 reduction to CO performance with the yield of 185.39 μmol g−1 h-1 under visible light illumination because the oxygen vacancy self-doping largely enhanced three key factors in this process, including photoinduced charge generation, charge separation and transportation and interfacial reaction. This facile and versatile method could be potentially used for large scale production of colored TiO2 with a high photocatalytic CO2 reduction capability in the visible light illumination.

Raman response and transport properties of tellurium atomic chains encapsulated in nanotubes

Abstract: Tellurium can form nanowires of helical atomic chains. With their unique one-dimensional van der Waals structure, these nanowires are expected to show physical and electronic properties that are remarkably different from those of bulk tellurium. Here, we show that few-chain and single-chain van der Waals tellurium nanowires can be isolated using carbon nanotube and boron nitride nanotube encapsulation. With this approach, the number of atomic chains can be controlled by the inner diameter of the nanotube. The Raman response of the structures suggests that the interaction between a single-atomic tellurium chain and a carbon nanotube is weak, and that the inter-chain interaction becomes stronger as the number of chains increases. Compared with bare tellurium nanowires on SiO2, nanowires encapsulated in boron nitride nanotubes exhibit a dramatically enhanced current-carrying capacity, with a current density of 1.5 × 108 A cm−2 that exceeds that of most semiconducting nanowires. We also use our tellurium nanowires encapsulated in boron nitride nanotubes to create field-effect transistors with a diameter of only 2 nm. By isolating one-dimensional tellurium nanowires in boron nitride nanotubes, the electronic properties of the atomic chains can be measured and the structures used to create field-effect transistors.

Construction of core-shell PPy@MoS2 with nanotube-like heterostructures for electromagnetic wave absorption: Assembly and enhanced mechanism

Abstract: Herein, a novel core-shell PPy@MoS2 nanotube-like heterostructures were prepared with hollow polypyrrole nanotubes and intertwined MoS2 nanosheets as core and the outer shell, respectively, by combining chemical oxidative polymerization and hydrothermal process. The unique heterostructures endowed the designed composite with highly enhanced electromagnetic wave absorbing performance. In contrast to pristine hollow PPy nanotubes and MoS2 nanoflowers, the fabricated PPy@MoS2 composite not only possessed excellent reflection loss (RL) performance, but also displayed a broad absorbing bandwidth, which might be ascribed to the good impedance matching and multifarious loss pathways including dipole polarization, interfacial polarizations and conductive loss. Impressively, the widest bandwidth (RL

Fabrication of FeNi hydroxides double-shell nanotube arrays with enhanced performance for oxygen evolution reaction

Abstract: FeNi Hydroxides (FeNi-HD) have been considered as promising substitutes to noble metal electrocatalysts for oxygen evolution reaction (OER). In this work, we design and realize FeNi-HD nanotube arrays (FeNi-HDNAs) on Ni foam via an in-situ reaction and Kirkendall effect. The obtained catalysts possess higher specific surface area, more catalytic active sites and better chemical stability for OER. Electron migrations from the Fe 3d orbitals to Ni sites in the FeNi-HDNAs lead to more unoccupied Fe 3d states and a higher oxidation state. As expected, FeNi-HDNAs exhibit lower overpotential as well as lower Tafel slope and better durability than the Fe- or Ni-HD peers. DFT calculations elucidate that FeNi hydroxides lower the energy barrier of rate-determining step in OER. Moreover, a high current density of 10 mA cm−2 is obtained at a low potential of 1.49 V using FeNi-HDNAs as the bifunctional electrocatalyst for overall water splitting in basic solution.

Atomically Dispersed Iron–Nitrogen Sites on Hierarchically Mesoporous Carbon Nanotube and Graphene Nanoribbon Networks for CO2 Reduction

Abstract: Atomically dispersed metal and nitrogen co-doped carbon (M-N/C) catalysts hold great promise for electrochemical CO2 conversion. However, there is a lack of cost-effective synthesis approaches to meet the goal of economic mass production of single-atom M-N/C with desirable carbon support architecture for efficient CO2 reduction. Herein, we report facile transformation of commercial carbon nanotube (CNT) into isolated Fe-N4 sites anchored on carbon nanotube and graphene nanoribbon (GNR) networks (Fe-N/CNT@GNR). The oxidization-induced partial unzipping of CNT results in the generation of GNR nanolayers attached to the remaining fibrous CNT frameworks, which reticulates a hierarchically mesoporous complex and thus enables a high electrochemical active surface area and smooth mass transport. The Fe residues originating from CNT growth seeds serve as Fe sources to form isolated Fe-N4 moieties located at the CNT and GNR basal plane and edges with high intrinsic capability of activating CO2 and suppressing hydrogen evolution. The Fe-N/CNT@GNR delivers a stable CO Faradaic efficiency of 96% with a partial current density of 22.6 mA cm-2 at a low overpotential of 650 mV, making it one of the most active M-N/C catalysts reported. This work presents an effective strategy to fabricate advanced atomistic catalysts and highlights the key roles of support architecture in single-atom electrocatalysis.

Confined water-mediated high proton conduction in hydrophobic channel of a synthetic nanotube

Abstract: Water confined within one-dimensional (1D) hydrophobic nanochannels has attracted significant interest due to its unusual structure and dynamic properties. As a representative system, water-filled carbon nanotubes (CNTs) are generally studied, but direct observation of the crystal structure and proton transport is difficult for CNTs due to their poor crystallinity and high electron conduction. Here, we report the direct observation of a unique water-cluster structure and high proton conduction realized in a metal-organic nanotube, [Pt(dach)(bpy)Br]4(SO4)4·32H2O (dach: (1R, 2R)-(-)-1,2-diaminocyclohexane; bpy: 4,4'-bipyridine). In the crystalline state, a hydrogen-bonded ice nanotube composed of water tetramers and octamers is found within the hydrophobic nanochannel. Single-crystal impedance measurements along the channel direction reveal a high proton conduction of 10-2 Scm-1. Moreover, fast proton diffusion and continuous liquid-to-solid transition are confirmed using solid-state 1H-NMR measurements. Our study provides valuable insight into the structural and dynamical properties of confined water within 1D hydrophobic nanochannels.

Mesoporous Single-Atom-Doped Graphene–Carbon Nanotube Hybrid: Synthesis and Tunable Electrocatalytic Activity for Oxygen Evolution and Reduction Reactions

Abstract: Mesoporous heteroatom-doped carbon-based nanomaterials are very promising as catalysts for electrochemical energy conversion and storage. We have developed a one-step catalytic chemical vapor deposition method to grow a highly graphitized graphene nanoflake (GF)–carbon nanotube (CNT) hybrid material doped simultaneously with single atoms of N, Co, and Mo (N–Co–Mo–GF/CNT). This high-surface-area material has a mesoporous structure, which facilitates oxygen mass transfer within the catalyst film, and exhibits a high electrocatalytic activity and stability in oxygen reduction and evolution reactions (ORR and OER) in alkaline media. We have shown that in this metal (M)–N–C catalyst, M (Co, Mo)–C centers are the main sites responsible for OER, while, for ORR, both M and N–C centers synergistically serve as the active sites. We systematically investigated tuning of the ORR and OER activity of the porous catalyst depending on the choice of the underlying substrate. The ORR kinetic current and OER activity for N–Co–Mo–GF/CNT were significantly enhanced when the catalyst was deposited onto a Ni substrate, resulting in an advanced electrocatalytic performance compared to the best bifunctional ORR/OER catalysts reported so far. Using a developed scanning electrochemical microscopy analysis method, we demonstrated that the higher OER reactivity on Ni was attributable to the formation of underlying catalyst/Ni interfacial sites, which are accessible due to the porous, electrolyte-permeable structure of the catalyst.

Three-Dimensional N-Doped Carbon Nanotube Frameworks on Ni Foam Derived from a Metal-Organic Framework as a Bifunctional Electrocatalyst for Overall Water Splitting.

Abstract: Rational design of bifunctional, high-performance, and stable non-noble metal-based electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great importance and challenging for the realization of overall water splitting. Metal-organic frameworks (MOFs) have been intensively studied as pyrolyzing precursors to prepare electrocatalysts. However, the aggregation of powder and the low conductivity of polymer binders have limited the applications of powder electrocatalysts. Therefore, the direct growth of MOFs on conductive and porous substrates will be a favorable way to prepare efficient electrocatalysts for electrocatalytic water splitting. Herein, we report a facile strategy for constructing three-dimensional N-doped carbon nanotube frameworks derived from metal-organic framework on Ni foam as a bifunctional electrocatalyst for overall water splitting. The resulting electrocatalyst exhibits excellent stability and high OER and HER activity with rather low overpotentials of 230 and 141 mV at 10 mA/cm2 in 1.0 M KOH, respectively. Specifically, the as-synthesized electrodes were used as both the cathode and anode for overall water splitting with 10 mA/cm2 at a cell voltage of only 1.62 V. The outstanding electrocatalytic performance is mainly attributed to a large number of accessible active sites of Co nanoparticles dispersed by the N-doped carbon nanotubes (CNTs) and the ultra-high surface area of CNT frameworks. The presented strategy offers a novel approach for developing MOF-derived nanocarbon materials on Ni foam for electrocatalysis and electrochemical energy devices.

Self‐Catalyzed Growth of Co–N–C Nanobrushes for Efficient Rechargeable Zn–Air Batteries

Abstract: Highly efficient and stable bifunctional electrocatalysts for oxygen reduction and evolution are essential for aqueous rechargeable Zn-air batteries, which require highly active sites as well as delicate structural design for increasing effective active sites and facilitating mass/electron transfer. Herein, a scalable and facile self-catalyzed growth strategy is developed to integrate highly active Co-N-C sites with 3D brush-like nanostructure, achieving Co-N-C nanobrushes with Co,N-codoped carbon nanotube branches grown on Co,N-codoped nanoparticle assembled nanowire backbones. Systematic investigations suggest that nanobrushes deliver significantly improved electrocatalytic activity compared with nanowire or nanotube counterparts and the longer nanotube branches give the better performance. Benefiting from the increase of accessible highly active sites and enhanced mass transfer and electron transportation, the present Co-N-C nanobrush exhibits superior electrocatalytic activity and durability when used as a bifunctional oxygen catalyst. It enables a rechargeable Zn-air battery with a high peak power density of 246 mW cm-2 and excellent cycling stability. These results suggest that the reported synthetic strategy may open up possibilities for exploring efficient electrocatalysts for diverse applications.

Confined active species and effective charge separation in Bi4O5I2 ultrathin hollow nanotube with increased photocatalytic activity

Abstract: Novel 1D Bi4O5I2 hollow nanotube (Bi4O5I2-HNT) material has been controlled synthesized via a facile PVP-assisted solvothermal method for the first time. Different parameters to control the formation of Bi4O5I2-HNT were tuned, such as usage amount of PVP, reaction temperature and mannitol concentration. Furthermore, structure, surface chemical composition, optical absorption ability and photogenerated charge separation efficiency of as-prepared Bi4O5I2 nanosheet and Bi4O5I2-HNT samples have been measured. Benefiting from the specific ultrathin hollow nanotube structure to produce confined highly concentrated active species and excellent electrical conductivity, Bi4O5I2-HNT material exhibited the increased photocatalytic degradation performance towards bisphenol A relative to Bi4O5I2 nanosheet. This work opens the door for designing other Bi-based photocatalysts via facile soft-template-assisted method to achieve a high-efficient photocatalytic performance.

Stretchable conductor based on carbon nanotube/carbon black silicone rubber nanocomposites with highly mechanical, electrical properties and strain sensitivity

Abstract: Stretchable conductive polymer composites are important in the field of flexible electronic devices, in which stretchable conductive silicone rubber composites has drawn great attention. However, the poor mechanical properties of the SR composites limit their practical application. How to compensate this drawback without compromising its electrical conductivity is an issue deserved to investigate. Herein, conductive carbon black grafted with a silicone coupling agent was prepared by free radical polymerization, and further reacted with carbon nanotube to obtain a new carbon black-carbon nanotube hybrid filler. This hybrid filler can not only improve the mechanical properties of silicone rubber composites, but also greatly enhance their electrical conductivity. Consequently, a silicone rubber composite with 5.76 vol% hybrid filler has high tensile strength (4.5 MPa) and elongation at break (211%). The minimum conductive percolation threshold and maximum conductivity of the composite are 0.24 vol% and 248.8 S/m, respectively. Besides, the composite has high strain sensitivity and superior deformation recovery performance, and can be applied to detect human motion behavior under a low strain. The preparation method of the hybrid filler provides a novel approach to the preparation and production of stretchable conductive composites with good mechanical properties and potential application for flexible electronic devices.

In situ conversion of metal (Ni, Co or Fe) foams into metal sulfide (Ni3S2, Co9S8 or FeS) foams with surface grown N-doped carbon nanotube arrays as efficient superaerophobic electrocatalysts for overall water splitting

Abstract: High-efficiency electrocatalysts at large current densities require consideration of not only the intrinsic activities but also the surface geometric structures. Here, we report a simple strategy to obtain metal sulfide (Ni3S2, Co9S8 and FeS) foams by in situ conversion of commercial Ni, Co and Fe foams through a conventional annealing reaction. Interestingly, N-doped carbon nanotubes, which are catalyzed by the corresponding metal sulfide nanocrystals, can also be obtained on the surface of the foams. The as formed Ni3S2 foams can work as bifunctional electrodes for overall water splitting with a potential of 1.5 V and 1.72 V at a current density of 10 mA cm−2 and 100 mA cm−2, respectively, which are comparable to the state-of-the-art transition-metal-sulfide-based bifunctional electrocatalysts reported to date. Factors such as abundant electrocatalytic active sites and excellent conductivity contribute to the gas evolution properties of nickel sulfide foams. Interestingly, the prominent performance of the nickel sulfide foams is also due to the nanotube array coating which provides special superaerophobic structures. The unique surface geometry provides little solid–gas contact area (solid content as low as 2%) at the electrode/bubble interface, and ultrasmall gas bubbles with diameters below 100 μm can leave the surface of the electrodes with ease, which effectively reduces the bubble overpotential and greatly promotes gas evolution properties especially at high current densities. Our research provides a facile strategy to obtain superaerophobic surface geometry for in situ prepared transition metal sulfide foams, which can work as bifunctional electrocatalysts for overall water splitting at large current densities. These findings may bring new insights in the design of efficient electrocatalysts for overall water splitting.

Precise pitch-scaling of carbon nanotube arrays within three-dimensional DNA nanotrenches.

Abstract: Precise fabrication of semiconducting carbon nanotubes (CNTs) into densely aligned evenly spaced arrays is required for ultrascaled technology nodes. We report the precise scaling of inter-CNT pitch using a supramolecular assembly method called spatially hindered integration of nanotube electronics. Specifically, by using DNA brick crystal-based nanotrenches to align DNA-wrapped CNTs through DNA hybridization, we constructed parallel CNT arrays with a uniform pitch as small as 10.4 nanometers, at an angular deviation 95%.

Construction of Fe2O3@CuO Heterojunction Nanotubes for Enhanced Oxygen Evolution Reaction

Abstract: Delicate design and controllable fabrication of efficient oxygen evolution reaction (OER) electrocatalysts based on earth-abundant elements is a highly desired yet challenging task. Herein, Fe2O3@C...

Free-Standing N-Doped Carbon Nanotube Films with Tunable Defects as a High Capacity Anode for Potassium-Ion Batteries

Abstract: Potassium-ion batteries (KIBs) have aroused enormous interest for future energy storage technology. However, the current anodes for KIBs greatly suffer from the rapid capacity fading and inferior r...