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Single-walled carbon nanotubes (SWCNTs) have been attracting extensive attention due to their excellent properties. We have developed a strategy of using coal to synthesize SWCNTs for high performance field-effect transistors (FETs). The high-quality SWCNTs were synthesized by laser ablation using only coal as the carbon source and Co-Ni as the catalyst. We show that coal is a carbon source superior to graphite with higher yield and better selectivity toward SWCNTs with smaller diameters. Without any pre-purification, the as-prepared SWCNTs were directly sorted based on their conductivity and diameter using either aqueous two-phase extraction or organic phase extraction with PCz (poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl]). The semiconducting SWCNTs sorted by one-step PCz extraction were used to fabricate thin film FETs. The transformation of coal into FETs (and further integrated circuits) demonstrates an efficient way of utilizing natural resources and a marvelous example in green carbon technology. Considering its short steps and high feasibility, it presents great potential in future practical applications not limited to electronics. Coal was transformed by laser ablation into single-walled carbon nanotubes, which were used to fabricate field effect transistors after one-step purification.

The selective growth of semiconducting single-walled carbon nanotubes (s-SWCNTs) is of great importance in many high-end applications represented by nanoelectronics. Here, we developed a general approach to grow horizontally aligned s-SWCNT arrays on stable temperature (ST)-cut quartz with bimetallic catalysts using carbon monoxide (CO) as both catalyst reductant and single component carbon feedstock under atmospheric pressure. The disproportionation of CO produces not only carbon species for SWCNT growth but also CO2, which could act as an in-situ etchant to remove both amorphous carbon and metallic tubes. The employment of bimetallic catalyst and quartz substrate facilitates the selective etching by narrowing the diameter distribution of as-grown SWCNT arrays. At the optimized conditions, we realized the selective growth of horizontally aligned s-SWCNT arrays with the content above 97% using CoCu catalysts, confirmed by Raman characterization and electrical measurements of the fabricated field effect transistor devices. This CO-based process in selective growth of s-SWCNTs has demonstrated its feasibility and universality by the broad growth window and applicability for other bimetallic catalysts, such as FeCu and CoMn. It possesses a practical potential in obtaining semiconducting channel materials for the scalable fabrication of CNT-based devices.[Figure not available: see fulltext.] © 2023, Tsinghua University Press.

After chirality-specified growth of single-walled carbon nanotubes (SWCNTs) was realized by tungsten-based intermetallic compound catalysts, here we developed a different kind of intermetallic compound, cobalt disilicide (CoSi2), as catalysts to selective grow carbon nanotubes by chemical vapor deposition (CVD). By using methane as carbon source, we obtained (11, 7) tubes with the selectivity of ∼24% and semiconducting SWCNTs (s-SWCNTs) with the purity of ∼93% simultaneously. Because of the sensitivity of CoSi2 toward the oxygen-containing environment at high temperatures, ethanol is not a good carbon feedstock. Our results not only expand the chirality library and catalyst database in the chirality-selective synthesis of SWCNTs, but also further demonstrate the feasibility of intermetallic compound catalysts. © 2022 Wiley-VCH GmbH

Tungsten disulphide has attracted great research interest due to its layered structure as well as physical and chemical properties. A less common type of tungsten sulphide, WS3, has also been studied as an electrochemical catalyst, but its crystal structure remains unclear because it has only been prepared in the amorphous form. In this work, crystalline WS3 is synthesized with a desert-rose-like morphology through the sulphurization of WO3 center dot 0.33H(2)O in a solvothermal reaction. The composition of WS3 is confirmed by X-ray photoelectron spectroscopy measurements as well as thermogravimetric experiment. The crystalline WS3 also has a layered structure and is likely to belong to the trigonal crystal system. Its lattice parameters in the hexagonal description are 5.30 angstrom x 5.30 angstrom x 29.0 angstrom , which are determined by 3D electron diffraction and powder X-ray diffraction. The WS3 shows potential as catalyst for the electrochemical hydrogen evolution reaction. Our findings extend the family of layered tungsten sulphide materials.

Single-walled carbon nanotubes (SWCNTs) are of particular interest as channel materials for field-effect transistors due to their unique structure and excellent properties. The controlled preparation of SWCNTs that meet the requirement of semiconducting and chiral purity, high density, and good alignment for high-performance electronics has become a key challenge in this field. In this Outlook, we outline the efforts in the preparation of SWCNTs for electronics from three main aspects, structure-controlled growth, selective sorting, and solution assembly, and discuss the remaining challenges and opportunities. We expect that this Outlook can provide some ideas for addressing the existing challenges and inspire the development of SWCNT-based high-performance electronics. © 2022 The Authors. Published by American Chemical Society.

Possessing excellent electronic and mechanical properties and great stability, single-walled carbon nanotubes (SWCNTs) are exceptionally attractive in fabricating flexible transparent conductive films. Doping is a key step to further enhance the conductivity of the SWCNT films and the reliable doping is highly needed. We developed a feasible strategy that uses solid acids such as phosphotungstic acid (PTA) to dope the SWCNT films stably relying on the nonvolatility of the dopants. The sheet resistance of the films was reduced to around a half of the original value meanwhile with no obvious change in transmittance. The doping effect maintained during a 700 days' observation. The excellent flexibility of the PTA-doped films was demonstrated by a bending test of 1000 cycles, during which the sheet resistance and transmittance was basically unaffected. The blue shifts of G band in the Raman spectra and the increase of work function measured by the Kelvin probe force microscopy both reveal the p-type doping of the films by PTA. The strong acidity of PTA plays a key role in the doping effect by increasing the redox potential of the ambient O2 and thus the Fermi level of the SWCNTs is brought down. The great feasibility and robustness of our doping strategy are desirable in the practical application of SWCNT-based flexible transparent conductive films. This strategy can be extended to the p-type doping of various CNT-based assemblies (such as sponges and forests) as well as other material families, expanding the application spectrum of polyacids. © 2021 American Chemical Society.

Single-walled carbon nanotubes (SWCNTs) present excellent electronic and mechanical properties desired in wearable and flexible devices. The preparation of SWCNT films is the first step for fabricating various devices. This work developed a scalable and feasible method to assemble SWCNT thin films on water surfaces based on Marangoni flow induced by surface tension gradient. The films possess a large area of 40 cm × 30 cm (extensible), a tunable thickness of 15 ∼ 150 nm, a high transparency of up to 96%, and a decent conductivity. They are ready to be directly transferred to various substrates, including flexible ones. Flexible strain sensors were fabricated with the films on flexible substrates. These sensors worked with high sensitivity and repeatability. By realizing multi-functional human motion sensing, including responding to voices, monitoring artery pulses, and detecting knuckle and muscle actions, the assembled SWCNT films demonstrated the potential for application in smart devices. © 2022

The growth of single-walled carbon nanotubes(SWCNTs) on substrates has attracted great interests because of the potential applications in various fields. Carbon monoxide(CO) was used as the carbon source for the growth of SWCNTs on silicon substrates. Random or oriented SWCNTs can be produced by varying the CO flow rate. When the flow rate of CO was as low as 20 sccm(sccm: standard cubic centimeter per minute), dense SWCNT networks with clean surface were produced. When the flow rate was above 50 sccm, vertically aligned SWCNT(VA-SWCNT) arrays were grown. Well-aligned VA-SWCNT arrays were obtained in the temperature range of 650–800 °C and the content of large-diameter(above 1.7 nm) tubes in the array increased with the temperature. The height of the array was affected by the growth temperature, the CO flow rate, and the growth time. These findings indicate CO can be used as an efficient carbon source for the growth of SWCNTs on substrates under low flow rates. © 2021, Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH.

We demonstrate a facile strategy to fabricate flexible paper-based supercapacitors, in which all the components are integrated onto a paper with poly (vinyl alcohol)/H3PO4 as the gel electrolyte. The electrodes are drawn on both sides of the paper in a mirror image with a surfactant-free ink of nitrogen-doped carbon nanotubes and graphene. The resultant supercapacitors present a high volumetric capacitance of 0.45 F cm(-3) and an energy density of 40.0 mu Wh cm(-3). Moreover, this strategy is intrinsically scalable toward flexible energy devices while maintaining their electrochemical and mechanical performance.

Possessing excellent electronic and mechanical properties and great stability, single-walled carbon nanotubes (SWCNTs) are exceptionally attractive in fabricating flexible transparent conductive films. Doping is a key step to further enhance the conductivity of the SWCNT films and the reliable doping is highly needed. We developed a feasible strategy that uses solid acids such as phosphotungstic acid (PTA) to dope the SWCNT films stably relying on the nonvolatility of the dopants. The sheet resistance of the films was reduced to around a half of the original value meanwhile with no obvious change in transmittance. The doping effect maintained during a 700 days' observation. The excellent flexibility of the PTA-doped films was demonstrated by a bending test of 1000 cycles, during which the sheet resistance and transmittance was basically unaffected. The blue shifts of G band in the Raman spectra and the increase of work function measured by the Kelvin probe force microscopy both reveal the p-type doping of the films by PTA. The strong acidity of PTA plays a key role in the doping effect by increasing the redox potential of the ambient O2 and thus the Fermi level of the SWCNTs is brought down. The great feasibility and robustness of our doping strategy are desirable in the practical application of SWCNT-based flexible transparent conductive films. This strategy can be extended to the p-type doping of various CNT-based assemblies (such as sponges and forests) as well as other material families, expanding the application spectrum of polyacids. © 2021 American Chemical Society.

The diameter-controlled growth of single-walled carbon nanotubes (SWNTs) is one of the key issues of SWNT synthesis and application. To guarantee that SWNTs grow with desired diameters, it is necessary to control catalyst size and modulate growth conditions. SWNTs with diameters of 0.9–1.2 nm are highly desirable for near-infrared fluorescence bioimaging and serving as effective single-photon sources for the development of quantum devices. Herein, we used an FeCo/MgO catalyst to grow bulk SWNTs with diameters in the range and studied the influence of catalysts and chemical vapor deposition (CVD) growth conditions on the diameter of SWNTs. The preparation of catalyst precursors is a key step in obtaining catalyst nanoparticles of small size. In the impregnation process, we used three different types of metal salts, namely, sulfates, acetates, and nitrates, to prepare the catalysts. The metal sulfates, which exhibit the weakest hydrolysis ability, were found to grow SWNTs with the smallest diameters. Lowering the immersion pH, which suppresses the hydrolysis of metal ions, was also favorable for growing smaller SWNTs. Moreover, the addition of complexing agent molecules such as ethylenediaminetetraacetic acid during the impregnation process, which inhibits the hydrolysis of metal ions as well, further confined the diameter distribution of the resultant SWNTs. During the solution drying process, metal salts hydrolyze into metal hydroxides and oxides. Under mild hydrolysis conditions, the produced hydroxide and oxide particles are smaller and more likely to be uniformly distributed on the surface of the supports. Therefore, it is more favorable to produce catalysts with controlled sizes under mild hydrolysis conditions, which are preferred for diameter control of the resultant SWNTs. In the CVD growth process, we used either ethanol or methane as the carbon source and found that, under our experimental conditions, the SWNTs grown from ethanol had smaller diameters than

In the context of growing population and increasing greenhouse gas emissions, urban energy planning is becoming a topic of high concern. With the rapid pace of urban construction, it is claimed that 40% of America’s total energy consumption is accounted by the building sector. Energy modelling and simulation are believed to be effective in supporting urban energy planning. Today, the growing availability of 3D city models has facilitated energy simulations at various scales. While Building Information Model (BIM) provides users with the possibility to explore the energy consumption alternatives of a single building, GIS-based city-wide building models offer the chance to simulate urban energy demand at the city scale. Considering that most of the existing GIS-based building energy simulations are using models with a lower Level of Detail (LoD), the aim of this study is to extract geometrically detailed and semantically correct information from BIM models to construct GIS models with a higher LoD in order to support more accurate Building energy simulations. Semantics of BIM models from different sources are matched with that of GIS-based building models, and geometry of BIM models are converted to conform to GIS-based building model standards. Specific concern is given to the extraction of openings that are absent from lower LoD CityGML. After conversion, the result is used to perform a simple energy assessment to see how much influence a higher LoD CityGML model has on the energy simulation of a building., Urban energy planning is becoming a hot topic in the context of growing population and increasing greenhouse gas emissions. With the rapid pace of urban construction, it is claimed that 40% of America’s total energy consumption is accounted by the building sector. Energy modelling and simulation are believed to be effective in supporting urban energy planning. Today, the growing availability of 3D city models has facilitated energy simulations at various scales. While Building Information Model (BIM) provides users with detailed information of a single building and allows the evaluation energy consumption in different scenarios, GIS-based city-wide building models offer the chance to simulate urban energy demand at the city scale. For the lack of detail in most GIS based 3D models, the energy simulation from these models are generally biased. A general workflow has been developed in the thesis to convert BIM to a detailed GIS-based city model. After conversion, the result is used to perform a simple energy assessment to see how much influence a more detailed GIS-based model has on the energy simulation of a building. The result shows that taking extra information from BIM to improve the result of energy simulation of a GIS-based model is feasible. And the magnitude of the improvement is worth considerable concern.