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Preparation of high-efficiency dual-functional catalysts remains the bottleneck for electrochemical water splitting. To prepare a non-precious metal catalyst with high activity and stability, here, we present a seaweed-like structure consisting of transition-metal sulfide nanoplates self-assembled on carbon nanotube sponge networks (SW-CoS@CNT). By adjusting the key parameters during synthesis (e.g., the loading amount and ratio of Co and S precursors), the microstructure can be tailored in a wide range, and sulfur defects can be introduced into the nanoplates by thermal annealing. The resulting SW-CoS@CNT serves as a freestanding dual-functional catalytic electrode, showing low overpotentials of 105 and 218 mV for the hydrogen evolution reaction and the oxygen evolution reaction, respectively, which are superior to most reported transition-metal-sulfide-based catalysts in alkaline solution. Rational design of this hierarchical biomimetic structure may be useful in developing high-performance electrochemical catalysts in renewable energy and environmental fields.

The development of flexible and wearable electronic devices has put an increasing demand on electrode systems with seamless connection and high compatibility with the main device, in order to accommodate complex deformation conditions and maintain stable performance. Here, we present a carbon nanotube-integrated electrode (CNTIE) by wet-pulling the ends of a carbon nanotube (CNT) film to form condensed thin fibers that resemble conventional conducting wire electrodes. A flexible strain sensor was constructed consisting of the middle CNT film as the main functional part and the CNTIE as self-derived electrodes, with inherent CNT connection between the two parts. The sensor can be transferred to versatile substrates (e.g., balloon surface) or encapsulated in thermoplastic polymers, exhibiting a large linear response range (up to 1000% in tensile strain), excellent durability and repeatability over 5000 cycles, and the ability to detect small- to large-degree human body motions. In addition, the strain sensor based on the CNTIE hybrid film (MXene/CNT and graphene/CNT) also shows superior linearity and stability at a strain range of 0-800%. Compared with the sensors using traditional silver wire electrodes and separately fabricated CNT fiber electrodes, our CNTIE plays an important role in achieving highly stable performance in the strain cycles. Our self-derived integrated electrodes provide a potential route to solve the incompatibility issues of conventional electrodes and to develop high-performance flexible and wearable systems based on CNTs and other nanomaterials.

Organic-inorganic hybrid perovskites have emerged in the last decade as promising semiconductors due to the excellent optoelectronic properties. This kind of perovskites exhibited respectable photocatalytic activities toward potential application in battery; however, the instability issue still hindered their practical use. Herein, a hybrid perovskite material, 4,4'-ethylenedipyridinium lead bromide [(4,4'-EDP)Pb

Two-dimensional (2D) MXene nanosheets are attractive for electrochemical energy storage applications due to their superior surface-controlled charge storage capacity. However, the slow ion transport in the closely packed electrode limits their electrochemical performances. Meanwhile, the restricted surface-controlled pseudocapacitance of MXene nanosheets requires to be enhanced. Herein, a well-controlled electrophoretic deposition strategy is developed to disperse Ti

Carbon nanotube-silicon (CNT-Si) solar cells represent one of the alternative photovoltaic techniques with potential for low cost and high efficiency. Here, we report a method to improve solar cell performance by depositing conventional transitional metal oxides such as WO3 and establishing a collaborative system, in which CNTs are well-embedded within the WO3 layer and both of them are in close contact to Si substrate. This unique collaborative system optimizes the overall energy conversion process including the light absorption (antireflection by WO3), carrier separation (forming quasi p-n junction) and charge collection (CNT conductive network throughout the oxide layer). Combining with our previous TiO2-coating and HNO3-doping techniques, a solar cell efficiency of >18% at an active area of 0.09 cm2 (air mass 1.5, 100 mW/cm2) was achieved. The oxide-enhanced CNT-Si solar cells which integrate the advantages of traditional semiconductors and novel nanostructures represent a promising route toward next-generation high-performance silicon-based photovoltaics.

Carbon nanotube functional materials (CNTFMs) represent an important research field in transforming nanoscience and nanotechnology into practical applications, with potential impact in a wide realm of science, technology, and engineering. In this review, we combine the state-of-the-art research activities of CNTFMs with the application prospect, to highlight critical issues and identify future challenges. We focus on macroscopic long fibers, thin films, and bulk sponges which are typical CNTFMs in different dimensions with distinct characteristics, and also cover a variety of derived composite/hierarchical materials. Critical issues related to their structures, properties, and applications as robust conductive skeletons or high-performance flexible electrodes in mechanical and electronic devices, advanced energy conversion and storage systems, and environmental areas have been discussed specifically. Finally, possible solutions and directions are proposed for overcoming current obstacles and promoting future efforts in the field.

The recent boom in large-scale energy storage system promotes the development of lithium-oxygen batteries because of their high theoretical energy density. However, their applications are still limited by the sluggish kinetic, insoluble discharge product deposition and the undesired parasitic reaction. Herein, the free-standing nitrogen doped reduced graphene oxide/Co(OH)2 (NRGO/Co(OH)2) composite films were prepared by a facile hydrothermal method. The NRGO/Co(OH)2 composite films display interconnected three-dimensional conductive network, which can not only promote the diffusion of O2 and the transport of electrolyte ions, but also provide abundant storage space for discharge products. Moreover, the introduction of nitrogen-containing functional groups results in improved conductivity and electron adsorption ability, which can facilitate electron transport and enhance the surface catalytic activity. Combining with excellent catalytic performance, the lithium-oxygen batteries with NRGO/Co(OH)2 composite film cathodes deliver low charge overpotential and excellent cycling performance.

Graphene quantum dots (GQDs), have unique quantum confinement effects, tunable bandgap and luminescence property, with a wide range of potential applications such as optoelectronic and biomedical areas. However, GQDs usually have a strong tendency toward aggregation especially in making solid films, which will degrade their optoelectronic properties, for example, causing undesired fluorescence quenching. Here, we designed a composite film by embedding GQDs in a polyvinyl pyrrolidone (PVP) matrix through hydrogen bonding with well-preserved fluorescence, with a small addition of acid for compensating the poor conductivity of PVP. As a multifunctional solid coating on carbon nanotube/silicon (CNT/Si) solar cells, the photon down-conversion by GQDs and the PVP anti-reflection layer for visible light lead to enhanced external quantum efficiency (by 12.34% in the ultraviolet (UV) range) and cell efficiency (up to 14.94%). Such advanced optical managing enabled by low-cost, carbon-based quantum dots, as demonstrated in our results, can be applied to more versatile optoelectronic and photovoltaic devices based on perovskites, organic and other materials.

Iron fluoride compounds offer an exciting pathway towards low-cost and high-capacity conversion-type lithium ion batteries cathodes. However, due to the sluggishness of the electronic and ionic tra...

Since Akira Yoshino first proposed the usage of the carbonaceous materials as an anode of lithium ion batteries (LIBs) in 1985, carbonaceous materials such as graphite and graphene have been widely considered as LIB anodes. Here, we explored the application of novel carbonaceous LIB anodes incorporating graphene quantum dots (GQDs). We fabricated a freestanding all-carbon electrode based on a porous carbon nanotube (CNT) sponge via a facile in-situ hydrothermal deposition technique, creating coaxial structure of GQD-coated CNTs (GQD@CNTs) through electrostatic interaction and π-π stacking with tunable loading and functionalization. This hybrid structure combined conductive CNTs with highly active GQDs, in which GQDs with predesigned functional groups provided massive storage sites for Li ions and the 3D CNT frameworks avoided the agglomeration of GQDs, together contributing to a high specific capacity (700 mAh}g−1 at 100 mA}g−1 after 100 cycles) and rate performance. Even at a high current density of 1,000 mA}g−1, the reversible specific capacity remained at 483 mAh}g−1 after 350 cycles. In particular, the mechanism study demonstrated the important role of oxygen functional groups of GQDs in promoting the performance of the LIB anodes by controlled grafting of GQDs onto various porous-carbon and metal-foam based structures.

Rational structure design of carbon nanomaterials including modulation of interlayer spacing and control of order degree, has been adopted to improve their electrochemical properties for high performance lithium-ion batteries (LIBs). Here, we construct three-dimensional (3D) architectures composed of intercrossed 1D graphitized-carbon nanotubes (g-CNTs) via a simple template synthesis. The g-CNT with high aspect ratio, can be viewed as a thin graphitized carbon sheet rolled up into a large hollow nanotube (average diameter: 222 nm). Its thin tube wall (3–4 nm) with multi-layered structure and relatively large interlayer spacing (3.73 nm) in short range can conduct fast diffusion of lithium ions (Li+), accommodate increased volume expansion and facilitate reversible Li+ intercalation/extraction. Particularly, heteroatoms like N and O are also doped in C patterns and would provide more active insertion or adsorption sites. Thus, the porous architectures are enabled to serve as freestanding anodes for LIBs, exhibiting a high specific capacity of ∼624 mA h/g at current density of 100 mA/g, stable long-term cycle stability, as well as good rate capability. Due to their larger tube cavity and 3D structures, our g-CNT architectures are further exploited as conductive frameworks to dual-load MnO2 nanoflowers, and would speed up the development of next-generation rechargeable LIBs.

Transitional metal oxides (TMOs) are important functional materials in silicon-based and thin-film optoelectronics. Here, TMOs are applied in carbon nanotube (CNT)-Si solar cells by spin-coating solutions of metal chlorides that undergo favorable transformation in ambient conditions. An unconventional change in solar cell behavior is observed after coating two particular chlorides (MoCl5 and WCl6, respectively), characterized by an initial severe degradation followed by gradual recovery and then well surpassing the original performance. Detailed analysis reveals that the formation of corresponding oxides (MoO3 and WO3) enables two primary functions on both CNTs (p-type doping) and Si (inducing inversion layer), leading to significant improvement in open-circuit voltage and fill factor, with power conversion efficiencies up to 13.0% (MoO3) and 13.4% (WO3). Further combining with other chlorides to increase the short-circuit current, ultimate cells efficiencies achieve >16% with over 90% retention after 24 h, which are among the highest stable efficiencies reported for CNT-Si solar cells. The transformation of functional layers as demonstrated here has profound influence on the device characteristics, and represents a potential strategy in low-cost manufacturing of next-generation high efficiency photovoltaics.

There have been intensive and continuous research efforts in large-scale controlled assembly of one-dimensional (1D) nanomaterials, since this is the most effective and promising route toward advanced functional systems including integrated nano-circuits and flexible electronic devices. To date, numerous assembly approaches have been reported, showing considerable progresses in developing a variety of 1D nanomaterial assemblies and integrated systems with outstanding performance. However, obstacles and challenges remain ahead. Here, in this review, we summarize most widely studied assembly approaches such as Langmuir-Blodgett technique, substrate release/stretching, substrate rubbing and blown bubble films, depending on three types of external forces: compressive, tensile and shear forces. We highlight the important roles of these mechanical forces in aligning 1D nanomaterials such as semiconducting nanowires and carbon nanotubes, and discuss each approach on their effectiveness in achieving high-degree alignment, distinct characteristics and major limitations. Finally, we point out possible research directions in this field including rational control on the orientation, density and registration, toward scale-up and cost-effective manufacturing, as well as novel assembled systems based on 1D heterojunctions and hybrid structures.

Metal-organic frameworks (MOFs) with high porosity and designable functionality make it possible to access the merits of high permeability and selectivity. However, scalable fabrication methods to produce mixed matrix membranes (MMMs) with good flexibility and ultrahigh MOF loading are urgently needed yet largely unmet. Herein, we report a thermally induced phase separation-hot pressing (TIPS-HoP) strategy to roll-to-roll produce 10 distinct MOF-membranes (loadings up to 86 wt%). Ultrahigh-molecular-weight polyethylene interweaving the MOF particles contributes to their mechanical strength. Rejections (99%) of organic dyes with a water flux of 125.7 L m–2 h–1 bar–1 under cross-flow filtration mode. The micron-sized channels between the MOF particles translate into fast water permeation, while the porous MOFs reject solutes through rapid adsorption. This strategy paves ways for developing high-performance membrane adsorbers for crucial separation processes. As a proof-of-concept, the abilities of the membrane adsorbers for separating racemates and proteins have been demonstrated., Mixed matrix membranes have shown great promise for separation applications, but low filler loading typically leads to low selectivity. Here the authors use a thermally induced phase separation-hot-pressing strategy to fabricate 10 distinct metal-organic framework-based membrane adsorbers with up to 86 wt% MOF-loading.

The widespread utilization of phase change materials (PCMs) in thermal energy storage technologies is often limited by the shape instability, rigidity, low conductivity and lack of multi-driven capabilities. Therefore, the functionalization of PCMs in order to overcome the aforementioned issues has remained an elusive goal. Herein, we infiltrate a polyethylene glycol (PEG) based solid-solid PCM into the pores of carbon nanotube sponge (CNTS) to fabricate a dual form-stable, flexible and highly conductive phase change composites (PCCs). The developed PCCs undergo nanopore-confined solid-solid phase transition triggered by a low voltage or sunlight with high electro/photo to thermal energy storage efficiency (>94%). The reported energy conversion efficiencies for both electro and photo to thermal energy storage is highest among all functionalized PCCs and attributed to the excellent energy conversion/transfer performance of aligned carbon nanotubes (CNTs) network in the composite structure. In addition to extra shape stability, the solid-solid PCC present high axial thermal conductivity (2.4 W m−1k−1) as well as high-energy storage density 132 J g−1 which is close to solid-liquid PCCs. Therefore, this study provides routes towards the development of real-life applicable PCCs for thermal energy applications.

Carbon nanotubes (CNTs) have been integrated with silicon to construct CNT-Si heterojunction solar cells; doping CNTs is one of the promising techniques to improve the solar cell performance. Here, we propose a gas-doping method by exposing as-fabricated CNT-Si solar cells to ozone for a short time. We find that a 5-min ozone treatment does not destroy the CNT structure but produces a significant impact on the cell characteristics (output voltage and fill factor), increasing the cell efficiency from 5.29% to 12.70% without degradation in 24 h. Ozone treatment donates holes to CNTs; this p-doping effect increases the work function of CNTs and subsequently enhances the built-in potential and Schottky barrier at the heterojunction for more efficient charge separation. Moreover, the ozone-treated CNT-Si cell could combine other established techniques such as colloidal antireflection and acid doping, to achieve an instantaneous high efficiency of >17% under standard illumination conditions (air mass 1.5, 100 mW/cm2). Compared to many reported doping methods relying on liquid or hazardous chemicals, our dry gas-doping strategy is very simple, highly effective, environmentally benign, and compatible to low-cost large-area solar cell manufacturing.

The ability to tailor and enhance photoluminescence (PL) behavior in two-dimensional (2D) transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) is significant for pursuing optoelectronic applications. To achieve this, it has been essential to obtain high-quality single-layer MoS2 and fully explore its intrinsic PL performance. Here, we fabricate single-layer MoS2 by a thermal vapor sulfurization method in which a pre-deposited molybdenum trioxide (MoO3) thin film is sulfurized over a short period (for several minutes) to turn into MoS2. These as-grown MoS2 crystals show quite strong PL, which is about one order of magnitude higher than that of chemical-vapor-deposited MoS2. Temperature- and power-dependent spectroscopy measurements disclose the apparent influence of sulfur (S) vacancies on the PL behavior and the noticeable free-to-bound exciton recombinations in the luminescence process. The fact that PL intensity of the sample in vacuum sharply lowered down relative to in air reveals that the high PL is facilitated by molecular adsorption on S vacancies in air. And multi-channel decay processes coupled with S vacancies are revealed in the time-resolved PL spectroscopy. In our work, single-layer MoS2 with high PL is synthesized and its defect-induced PL features are analyzed, which is of great importance for developing advanced nano-electronics and optoelectronics based on 2D structures.

Lithium–sulfur (Li–S) batteries are next-generation energy storage systems with high energy density, and the rate performance is a very important consideration for practical applications. Recent approaches such as introducing catalytic materials to facilitate polysulfide conversion have been explored, yet the results remain unsatisfactory. Here, we present an optimized Li–S electrode featured by a large amount of highly dispersed Co3S4 nanoparticles (∼10 nm in size) throughout a hierarchical carbon nanostructure hybridized from ZIF-67 and carbon nanotube (CNT) sponge. This enables homogeneous distribution and close contact between infiltrated sulfur and Co3S4 nanoparticles within the ZIF-67-derived N-doped carbon nanocubes, leading to effective chemical interaction with polysulfides, maximum catalytic effect and enhanced lithium ion diffusion, while the built-in three-dimensional CNT network ensures high electrical conductivity of the electrode. As a consequence, the Li–S battery exhibits both extraordina...

Solid-state supercapacitors (SSCs) are under intensive study during recent years; rational design of the electrode structure and device configuration is essential to bring high performance and enable flexibility. Here, we designed a mutually intercalated composite structure consisting of pseudo-polymer (polyaniline, PANI), graphene oxide (GO) and carbon nanotubes (CNTs), in various forms such as planar films or helical fibers. In the prepared PANI/GO/CNT composite films, PANI and GO were uniformly embedded among stacked CNT networks resulting in a synergistic effect from all components; as a result, the film with tunable PANI loading exhibited a specific capacitance of 729.3 F/g (510.5 mF/cm2) at 1 A/g in three-electrode configuration, and symmetric SSCs made by these films showed stable performance upon large-degree bending for 500 cycles. The composite film was further over-twisted into a helical fiber and constructed to fiber-shaped SSCs, which could work stably at elongations as much as 80%. Our polymer/carbon nanostructure composite electrodes that can work under different forms (films or fibers) have potential applications as flexible, stretchable and wearable energy storage devices and textiles.

Densely packed metal–organic framework (MOF) and carbon nanotube (CNT) hybrid materials with tailored hierarchical porous structure have been prepared by in situ growth and room temperature drying/shrinking. Optimizing the bulk density and porosity by controlling the MOF content leads to simultaneously high areal and volumetric capacities as lithium–sulfur battery electrodes, both of which are critical factors for developing high energy density and compact energy storage devices.

The assembly of single-walled carbon nanotubes (CNTs) into high-density horizontal arrays is strongly desired for practical applications, but challenges remain despite myriads of research efforts. Herein, we developed a non-destructive soft-lock drawing method to achieve ultraclean single-walled CNT arrays with a very high degree of alignment (angle standard deviation of ~0.03°). These arrays contained a large portion of nanometre-sized CNT bundles, yielding a high packing density (~400 µm

The transition metal sulfides/oxides have been considered as promising anode materials for lithium ion batteries due to their high theoretical capacities but have suffered limits from the unsatisfactory electronic conductivity and limited lifespan. Here, FeS micro-flowers are synthesized by hydrothermal treatment and are wared and grafted into layer-by-layer carbon nanotubes (CNT). Subsequently, FeS@Fe

Iron fluoride compounds offer an exciting pathway toward low-cost and high-capacity conversion-type lithium-ion battery (LIB) cathodes. However, due to the sluggishness of the electronic and ionic transport in iron fluorides, mass loadings of active materials in previous studies are typically less than 2.5 mg cm

Recently, room-temperature flexible gas sensors have been widely studied because they can operate without being heated and create low-cost, low-power-consumption devices with long-term stability. H...

Recently, room-temperature flexible gas sensors have been widely studied because they can operate without being heated and create low-cost, low-power-consumption devices with long-term stability. Here, by designing the active material composition and structure, we report an electrospun carbon nanofiber (CNF) network grafted by two-dimensional MoS

Developing advanced electrode materials for potassium-ion batteries (PIBs) is an emerging research area in recent years; so far, several strategies such as heteroatom doping into carbon, increasing interlayer spacing, or creating amorphous region in graphite have been investigated. Here, we studied the effect of sub-nanopores in a porous-carbon aerogel with a pore size distribution centered at around 0.8 nm and achieved outstanding PIB performance including long cycling stability (particularly at small current densities for prolonged charge/discharge period) and high rate capability with enhanced retentions. Mechanism studies reveal very high contribution from surface capacitive potassium (K)-ion storage (more than 90%) to the total capacity, and theoretical calculations show that 0.8 nm sub-nanopores lead to substantially low barrier for K-ion transport and storage, with ultrasmall diffusion energy and negligible lattice change. Sub-nanopore engineering, as demonstrated here, may be adopted to develop highly efficient and stable porous-carbon-based structures for applications in advanced energy storage systems and electrochemical catalysis.

A simple, inexpensive, and paintable bilayer coating approach enables both color and efficient cooling., Solar reflective and thermally emissive surfaces offer a sustainable way to cool objects under sunlight. However, white or silvery reflectance of these surfaces does not satisfy the need for color. Here, we present a paintable bilayer coating that simultaneously achieves color and radiative cooling. The bilayer comprises a thin, visible-absorptive layer atop a nonabsorptive, solar-scattering underlayer. The top layer absorbs appropriate visible wavelengths to show specific colors, while the underlayer maximizes the reflection of near-to-short wavelength infrared (NSWIR) light to reduce solar heating. Consequently, the bilayer attains higher NSWIR reflectance (by 0.1 to 0.51) compared with commercial paint monolayers of the same color and stays cooler by as much as 3.0° to 15.6°C under strong sunlight. High NSWIR reflectance of 0.89 is realized in the blue bilayer. The performances show that the bilayer paint design can achieve both color and efficient radiative cooling in a simple, inexpensive, and scalable manner.

Tailoring the structure of metal components and interaction with their anchored substrates is essential for improving the catalytic performance of supported metal catalysts; the ideal catalytic configuration, especially down to the range of atomic layers, clusters, and even single atoms, remains a subject under intensive study. Here, an Ir-on-MXene (Mo

Wide applications of compression-resistant electronics have promoted the demands for energy storage devices with high compressive strength. Herein, we fabricated highly dense graphene architectures (DGAs) embedded with solid electrolyte by evaporation-induced shrinkage of reduced graphene oxide (rGO) hydrogels filled with phosphoric acid/polyvinyl alcohol (H3PO4/PVA) electrolyte solution. In such DGAs, rGO sheets remain a stacked structure and solid electrolyte is uniformly distributed throughout the DGAs, forming a good contact between rGO sheets and solid electrolyte by hydrogen bonding interactions. The DGAs exhibit a high weight density of 1.5 g cm−3, excellent modulus of 234 MPa and high conductivity of 13.5 S m−1. Furthermore, the all-solid-state supercapacitors based on DGAs achieved a superior volumetric capacitance of about 155 F cm−3 at a current density of 0.1 A g−1. More importantly, the all-solid-state supercapacitors based on DGAs retain stable electrochemical properties under different compressive stresses.

Encoding a helical shape into straight fibers could bring unprecedented properties and explore applications in a broad range of areas; this has been difficult for graphene oxide (GO) fibers due to their relatively poor mechanical property and processability. Here, we incorporate a continuous single-walled carbon nanotube (SWNT) network into dispersed GO sheets to fabricate GO/SWNT composite films and helical fibers with an alternating layered structure. Our GO/SWNT fibers combine advantages from both the SWNTs (as a robust and conductive skeleton) and GO (as a hydrophilic matrix), leading to reversible mechanical actuation with axial contraction up to 50% of original fiber length in response to water adsorption. The structural evolution (including increase in fiber diameter and decrease in the helical loop number) is a key factor for generating large axial contraction. Graphene-based helical fibers embedding a continuous carbon nanotube network, as described here, have potential applications in flexible/wearable electronics, sensors and actuators.

Solar water evaporation is thought to be a promising solution to address the issues of global water scarcity. However, it is particularly difficult to achieve an idealized photothermal conversion membrane with all of the required structure characteristics such as wide spectrum absorption, ultrathin and porous, low thermal conductivity, and ease to scale up, thus leading to reduced water evaporation efficiency. Here, we designed a large-area bilayer Janus film by assembling gold nanorod (AuNR) onto the interconnected single-walled carbon nanotube (SWNT) porous film. The combined characteristics of high solar spectrum absorption, enhanced photothermal performance, thermal insulating feature, interconnected porous structure, and excellent mechanical performance enable the bilayer Janus film with a nearly 94% water evaporation efficiency under 5 kW m–2 solar irradiation and stable water generation capability during long-term illumination cycles as a water desalination membrane. Construction of the bilayer Jan...

The combination of nanostructures with biomaterials offers great opportunities in constructing innovative functional devices such as biosensors and actuators. Here, we create a multifunctional fiber by wrapping a thin film of carbon nanotubes (CNTs) on naturally found spider silks, which shows great flexibility and conductivity. The hybrid CNT-silk fiber demonstrates intimate contact with cardiomyocytes and can direct the cell growth and simultaneously record potential signals evoked from cell beating. Cell activities reflected in the form of potential signals have been monitored clearly and reliably through the CNT-silk fibers without degradation over the long term.

The edge site of two-dimensional (2D) transition metal dichalcogenides (TMDs) is active towards the hydrogen evolution reaction (HER). Herein, a feasible synthesis of sub-100 nm molybdenum/tungsten diselenide [Mo(1−x)WxSe2] crystals is described. The abundant edge exposure and heteroatom-doping synergistically boost the catalysis of HER by this material. In this work, sub-100 nm Mo(1−x)WxSe2 single crystals were grown on a nitrogen-doped multiwall carbon nanotube before being applied as HER electrocatalysts. At x = 0.13 ± 0.02, the Mo(1−x)WxSe2 shows optimal HER catalytic performance with low overpotentials (70 and 129 mV) required to achieve current densities of −1 and −10 mA cm−2, respectively, along with a Tafel slope of 53.6 mV dec−1 and an exchange current density of 49.5 μA cm−2. Density functional theory (DFT) calculations indicate that the Gibbs free energy of the HER process at the edge site of the crystals reaches a minimum value of 0.06 eV, which is lower than when the reaction is catalysed on Pt active sites. This study provides a general approach to increasing the edge proportion of the catalyst material and activating the terrace of the 2D materials for catalysis, which may be of benefit to the design and fabrication of other TMDs-based compounds.