Two-dimensional Nanostructures Research Articles

Many-body theory of trions in two-dimensional nanostructures

Many-body theory of trions in two-dimensional nanostructures

Magnetic Prediction of Doped Two-Dimensional Nanomaterials Based on Swin–ResNet

Magnetism is an important property of doped two-dimensional nanostructures. By introducing dopant atoms or molecules, the electronic structure and magnetic behavior of the two-dimensional nanostructures can be altered. However, the complexity of the doping process requires different strategies for the preparation and testing of various types, layers, and scales of doped two-dimensional materials using traditional techniques. This process is resource-intensive, inefficient, and can pose safety risks when dealing with chemically unstable materials. Deep learning-based methods offer an effective solution to overcome these challenges and improve production efficiency. In this study, a deep learning-based method is proposed for predicting the magnetism of doped two-dimensional nanostructures. An image dataset was constructed for deep learning using a publicly available database of doped two-dimensional nanostructures. The ResNet model was enhanced by incorporating the Swin Transformer module, resulting in the Swin–ResNet network architecture. A comparative analysis was conducted with various deep learning models, including ResNet, Res2net, ResneXt, and Swin Transformer, to evaluate the performance of the optimized model in predicting the magnetism of doped two-dimensional nanostructures. The optimized model demonstrated significant improvements in magnetism prediction, with a best accuracy of 0.9.

Self-supported NiCo2O4@Ni1.18S core-shell nanocomposite with impressive electrochemical properties suitable for hybrid supercapacitors

Self-supported NiCo2O4@Ni1.18S core-shell nanocomposite were synthesized on nickel foams by uniform growth Ni1.18S nanosheets encircling NiCo2O4 nanoneedles. Characterization results demonstrate that NiCo2O4@Ni1.18S core-shell nanocomposite have significant advantages in one - and two-dimensional nanostructure coordination structure, with richer REDOX active sites and more energy storage paths. Density functional theory (DFT) calculations results indicate that the surficial adsorption energy with OH− ions is enhanced in NiCo2O4@ Ni1.18S nanocomposite, thereby facilitating the reversible redox reaction kinetics and the electrochemical activity. As a result, self-supported NiCo2O4@Ni1.18S core-shell nanocomposite exhibit excellent energy-storage properties, i.e.: the specific charge capacity of 3158 F g−1 at 1 A g−1, high rate performance of 52.3 % from 1 A g−1 to 5 A g−1, and the 81.25 % capacity retention rate after 5000 cycles. Especially, it should be pointed out that the hybrid supercapacitors assembled from self-supported NiCo2O4@Ni1.18S core-shell nanocomposite and activated carbon present the wide voltage window (0–1.6 V), high energy density of 100.3 Wh kg−1 at power density of 177 W kg−1 and prospective commercial consideration. These facts fully prove the practical feasibility of self-supported NiCo2O4@Ni1.18S core-shell nanocomposite in advanced energy-storage facilities.

Advancing Protein Detection and Analysis Based on Ag/Au PHCN for Enhanced SERS Sensitivity and Specificity in Biomolecular Diagnostics.

In the realm of disease diagnostics, particularly for conditions such as proteinuria and hemoglobinuria, the quest for a method that combines accurate, label-free detection of protein compositions and their conformational changes remains a formidable challenge. In this study, we introduce an innovative Ag/Au plasmonic hybrid coupling nanoarray (Ag/Au PHCN) architecture marked by sub-10 nm interparticle gaps. These nanoarrays, leveraging plasmonic hybrid coupling and synergistic enhancement mechanisms, create a plethora of uniform surface-enhanced Raman spectroscopy (SERS) hotspots. The Ag/Au PHCN substrates demonstrated unparalleled sensitivity in the unmarked detection of hemoglobin (HGB), bovine serum albumin (BSA), and cytochrome C (Cyt.C) in bodily fluids, incorporating the advantages of high sensitivity, high reproducibility, durability, recyclability, and biocompatibility. Notably, the detection limits for BSA and HGB are unprecedented at 0.5 and 5 ng/mL, respectively. This achievement sets a new benchmark for label-free protein detection using two-dimensional nanostructures. Crucially, the Ag/Au PHCNs possess the novel capability to discern protein conformational changes post denaturation, underscoring their potential in probing protein functionalities. Most importantly, these nanoarrays can differentiate between normal and proteinuria-affected urine samples and monitor protein content variations over time, heralding a new era in clinical diagnostics with particular relevance to proteinuria and hemoglobinuria detection.

Inverse design of ultranarrow and high-efficiency color filters based on tandem convolutional neural networks

In this paper, an ultranarrow, high-efficiency color filter based on a two-dimensional grating nanostructure array is realized by a tandem inverse design network. The tandem inverse designed network is generated by connecting an inverse network with a pre-trained forward network. The tandem convolutional neural network successfully overcame the non-uniqueness problem of the training data. The performance of the networks is verified by a test set of 2592 data points, and the average MSE of the prediction results of the tandem network is 1.01 × 10−3. Extremely low error indicates that the tandem network can learn and capture the distribution characteristics of the transmission spectrum and give a reasonable design of the structural parameters. Finally, we obtained multiple inverse-designed transmissive color filters with ultranarrow linewidths and high efficiency, with central wavelengths between 480 nm and 630 nm. The linewidth and efficiency of each kind of color filter are less than 10.6 nm and higher than 60%. Narrow linewidths and wide wavelength tunability result in high color accuracy and a broad color gamut of the filters. The filters with two-dimensional metallic nanostructure array also show polarization-independent characteristics. Compared with the traditional method, this method can quickly and accurately design the structural parameters corresponding to the spectral response, which provides a new method for the nanostructure design.

Synergistic effects of multi-dimensionality in an aerogel for lithium-ion battery anodes with an enhanced capacitive contribution

The rational design of anode materials is important when seeking to produce high-performance lithium-ion batteries (LIBs) that offer both a high-power density (P) and a high energy density (ε). In this study, a multi-dimensional aerogel composed of 1-dimensional (1D) and two-dimensional (2D) nanostructures was synthesized. To impart conductivity and dimensional diversity, reduced graphene oxide (rGO) nanoplates were introduced to a 1D Co-S aerogel using a metal coordination-assisted sol–gel method. As the anode material for an LIB, the resulting multi-dimensional rGO@Co-S aerogel with 1.4 wt% GO exhibited outstanding electrochemical performance, with a high specific capacity, high-rate capability, strong cycling stability (84 % at 0.5 A/g after 350 cycles), an excellent P (9,660 W/kg), and a high ε (1,566 Wh/kg). This was attributed to the shorter ion and electron diffusion paths arising from the multi-dimensional structure, coupled with the higher surface area and enhanced capacitive contribution due to the addition of the rGO nanoplates.

Phase Engineering of Two-Dimensional WS2 Nanostructures for Superior Hybrid Supercapacitors

Two-dimensional (2D) tungsten sulfide (WS2) has recently emerged as a nontrivial material for electrochemical applications; however, the boundaries associated with its 1T (instability) and 2H (low electrical conductivity) phases limit its electrochemical parameters. In this work, this issue is addressed using an exclusive chemical approach to evolve a dual-phase 1T-2H WS2 heterostructure that combines two different 1T (trigonal) and 2H (hexagonal) phases directly on the current collector which demonstrated 2D transformable phase structure, large interlayer distance, and highly exposed edge active sites. A simple inert-atmosphere annealing approach under phosphorus vapors is designed to elicit a fractional phase conversion of WS2 from conventional 2H to the 1T phase, where phosphorus is accommodated in the WS2 interspace and lattice, resulting in interlayer expansion. Theoretical calculations confirmed that the 1T WS2 structure formed after phosphorus doping exhibits semimetallic feature with no band gap, thereby elucidating the high electrical conductivity. The presence of edge-enriched metallic phase and interlayer engineering of 1T-2H WS2 heterostructure validates the exceptional sodium (Na+) ion intercalation when tested in hybrid supercapacitor (HSCs) against Prussian blue analog (PBA) cathodes. As a result, the assembled HSC cell with a 1T-2H WS2 heterostructured anode and a CuFe-PBA cathode shows superior specific energy of 65.5 Wh kg-1 at a specific power of 784 W kg-1, and maintains 75% rate capability and 95.7%cycling stability over 10,000 cycles. This work paves a technique for engineering a simple phase transition of 2D materials and sheds light on the expansion of high-performance next-generation energy storage systems.

Mangenese Copper Selenide Nanosheet Arrays Derived from Metal-Organic Frameworks for Efficient Solid-State Asymmetric Supercapacitors

Metal chalcogenide nanostructures, particularly metal selenides, have unique properties, such as high electrical conductivity, large specific surface area, exclusive porous networks, and exceptional electrochemical properties compared to traditional nanostructures.1 2 A novel strategy is proposed to design and fabricate hierarchical Manganese copper selenide nanosheet (MnCuSe NS) arrays from metal-organic frameworks (MOFs). The hierarchical MnCuSe NS arrays can deliver enriched electroactive sites and shorten the ion/electron diffusion pathways. When evaluated as positive electrodes for supercapacitor (SC), the MnCuSe NS electrode displayed remarkable electrochemical properties with ultra-high specific capacity of ≈350.4 mA h g− 1 and an areal capacity of ≈0.94 mA h cm− 2 at a current density of 3 mA cm− 2, exceptional rate capability (≈79.5% of the capacity retention at a higher current density of 50 mA cm− 2), and outstanding cyclic stability (≈95.4 % of capacity retention after 10 000 cycles). Most importantly, the assembled MnCuSe NS//FeMnO/NG solid-state asymmetric SC exhibited a wide operating potential window of 1.6 V with an ultra-high volumetric capacity of ≈2.4 mA h cm− 3 at a current density of 3 mA cm− 2, an excellent energy density of ≈71.6 Wh Kg− 1 at a power density of ≈794 W Kg− 1, and ultra-long cycle life (≈93.4 % of capacity retention after 10 000 cycles). This proposed method provides a general protocol to design and fabricate metal selenide nanosheet arrays with superior electrochemical energy storage properties and exceptional cyclic stability, holding significant potential for future energy storage devices in commercial aspects. Keywords: Hierarchical, Metal-organic frameworks, Metal chalcogenide, Energy density, Asymmetric supercapacitorsReference:(1) Han, J. H.; Kwak, M.; Kim, Y.; Cheon, J. Recent Advances in the Solution-Based Preparation of Two-Dimensional Layered Transition Metal Chalcogenide Nanostructures. Chem. Rev. 2018, 118 (13), 6151–6188. https://doi.org/10.1021/acs.chemrev.8b00264.(2) Karuppasamy, K.; Vikraman, D.; Hussain, S.; Kumar Veerasubramani, G.; Santhoshkumar, P.; Lee, S.-H.; Bose, R.; Kathalingam, A.; Kim, H.-S. Unveiling a Binary Metal Selenide Composite of CuSe Polyhedrons/CoSe2 Nanorods Decorated Graphene Oxide as an Active Electrode Material for High-Performance Hybrid Supercapacitors. Chemical Engineering Journal 2022, 427, 131535. https://doi.org/10.1016/j.cej.2021.131535.

Synthetic Electronics

Building electronic circuitry with atomic precision is beyond the capability of current, as well as in the foreseeable future, top-down lithographic techniques. In recent years, the US Office of Naval Research (ONR) has championed several research initiatives that sought to address this key challenge. One of the most exciting development and initial success that resulted from these initiatives is a bottom-up chemical synthesis technique that has proven highly effective at assembling two-dimensional (2D) graphene nanostructures with spatial resolution down to single atom and single bond level. In this presentation I will briefly review, from a government program manager perspective, the current status of this exciting new research field which I call Synthetic Electronics. I will highlight some recent technical and scientific advances, such as various on-surface synthesis techniques, that enable and help define future directions of synthetic electronics. I will share some of my own personal perspectives and speculate on possible future directions, and also draw attention to some of the major challenges that are facing synthetic electronics. The motivation behind the discussion is to socialize the basic ideas and capabilities with, and seek feedback from, the relevant research communities, in order to inform and further refine research agenda in the future.

Micropatterning MXene/TiO2 Nanocomposite Ink for Gas Sensing

This work describes the preparation, characterization and micropatterning of MXene (Ti3C2/TiO2) nanocomposite inks. The MXene nanopowder was oxidized to Ti3C2/TiO2 nanocomposite powder by stirring in air for 3 hours using air aging method. The Ti3C2/TiO2 nanocomposite powder was then dispersed into Dimethyl Sulfoxide (DMSO) solvent, and the Ti3C2/TiO2 ink was prepared by using 1% mass fraction of Polyvinylpyrrolidone (PVP) solution as dispersant. The two-dimensional layered nanostructure of MXene and the characteristic peaks of TiO2 were observed by Raman and XRD results. SEM and TEM results show the layered structure of MXene nanoparticles as well as TiO2 nanoparticles with a diameter of about 2 nm on a single layer of MXene. FTIR results confirms that Ti-O bonds and Ti-C bonds indicating that part of Ti3C2 was oxidized to TiO2. The results of Brunauer Emmett Teller (BET) test on Ti3C2/TiO2 nanocomposite ink show that the specific surface area of the ink is 10.7194 m²/g and the maximum adsorption of N2 is 32.039cm3/g. Thermogravimetric analysis (TGA) indicate that Ti3C2/TiO2 exhibited excellent thermal stability, with a mass loss of only 15% at 800°C. In order to achieve the optimal printing effect, plasma surface treatment was carried out on the gold-plated silicon wafers, Polyethylene terephthalate (PET), and glass substrates, which decreases the contact angle of the ink on these substrates. The printing of Ti3C2/TiO2 nanocomposite ink on the substrate using the atomized printing technique with a mask plate enables printing of straight lines with a line width of 5µm. Film thickness can be controlled by adjusting the distance between the printhead and the substrate, as well as the pressure of the atomized printing jet.

A review of molybdenum disulfide-based 3D printed structures for biomedical applications

MoS2 is a substance, highly valued for its two-dimensional nanostructure and diverse physical and chemical properties. This review examines the advancements achieved in biomedical applications through the integration of molybdenum disulfide (MoS2), and the state-of-the-art area of 3D printing technology. It initially outlines MoS2 synthesis routes and techniques to tailor its properties. The review explores how MoS2 properties underpin its biological significance, thereby facilitating its therapeutic, tissue engineering, and biosensing applications. Emphasis is placed on the emerging area of 3D printing, assessing its potential when combined with MoS2 to produce customized materials for biomedical purposes. Strategies to create foam topologies and electrocatalytically active filaments in 3D-printed constructs are explained. The enhanced mechanical strength, conductivity, and therapeutic efficacy observed in 3D-printed MoS2 structures foreshadow new developments in healthcare, including the advent of biocompatible implants for regenerative medicine and tissue engineering. Further results show how innovations have been made in biosensing areas leveraging MoS2 3D printing. These insights, grounded in scientific research, medical practices, and technological advancements, position MoS2 as a flexible and innovative material with diverse applications across various biomedical sectors.

Solvothermal synthesis of PdCu nanorings with high catalytic performance for alcohol electrooxidation

Two-dimensional (2D) Pd-based nanostructures with a high active surface area and a large number of active sites are commonly used in alcohol oxidation research, whereas the less explored ring structure made of nanosheets with large pores is of interest. In this study, we detail the fabrication of PdCu nanorings (NRs) featuring hollow interiors and low coordinated sites using a straightforward solvothermal approach. Due to increased exposure of active sites and the synergistic effects of bimetallics, the PdCu NRs exhibited superior catalytic performance in both the ethanol oxidation reaction (EOR) and the ethylene glycol oxidation reaction (EGOR). The mass activities of PdCu NRs for EOR and EGOR were measured at 7.05 A/mg and 8.12 A/mg, respectively, surpassing those of commercial Pd/C. Furthermore, the PdCu NRs demonstrated enhanced catalytic stability, maintaining higher mass activity levels compared to other catalysts during stability testing. This research offers valuable insights for the development of efficient catalysts for alcohol oxidation.

The synergistic effect of Cd-doped and S-vacancies in CdxZn1-xIn2S4 2D nanosheets for high-performance triethylamine sensing

Ternary metal sulfides with suitable band gaps, high physicochemical stability, and unique two-dimensional (2D) nanostructures are expected to be the next-generation high-performance gas sensors following the MOS type. Doping engineering is utilized as an effective strategy to improve the semiconductor surface activity and enhance its gas-sensitive properties. In this paper, the energy band structure and surface chemical oxygen of ZnIn2S4 (ZIS) materials was tuned by selectively introducing substitutional Cd to replace the Zn sites in ZIS crystals. Meanwhile, the introduction of Cd-ions brings more abundant S vacancy defects, enhances the acid-base interactions at the interface, and pushes the extent of surface redox reactions. In addition, by combining the strong adsorption of ZIS to triethylamine, the CdxZn1-xIn2S4 nanosheets achieved highly improved sensing properties, including better response (63.38–100 ppm), enhanced selectivity (STEA/sother = 12.9), and accelerated response/recovery (4 s/32 s). The results confirm the feasibility of developing low-cost, high-performance 2D metal sulfide gas sensing materials through rational structural design and optimization.

The synergistic enhancement of photocatalytic activity by Fe3O4–TiO2 nanosheets for rhodamine B degradation

As an advanced oxidation material, Fe3O4-TiO2 nanocomposites have been widely used in wastewater treatment. However, conventional Fe3O4 nanoparticles suffer from drawbacks such as carrier recombination and aggregation, which seriously affect the catalytic activity. In this study, Fe3O4-TiO2 nanosheets with different TiO2 loading rates were synthesized by sol-gel method and solvothermal method. The unique two-dimensional nanostructure of Fe3O4 nanosheets facilitated the deposition of TiO2 nanoparticles, resulting in Fe3O4-TiO2 nanosheets with a high BET specific surface area of 121.67 m2·g−1. Under optimal experimental conditions, the degradation rate of RhB dye in the photocatalytic synergistic Fenton-like system constructed with Fe3O4-TiO2 nanosheets reached 98.12 % within 120 min, significantly surpassing that of single photocatalysis and Fenton-like systems. It was attributed to the unique surface structure of Fe3O4 nanosheets, which provided a larger contact area for TiO2 nanoparticles. It facilitated the effective reduction of Fe3+ to Fe2+ by photogenerated electrons in TiO2, inhibited the recombination of photogenerated electron-hole pairs, and consequently enhanced the degradation rate of RhB dye. Furthermore, Fe3O4-TiO2 magnetic nanosheets exhibited excellent reusability and stability, with the recovery rate and degradation rate of RhB dye remaining above 90 % even after five cycles. More importantly, the catalytic mechanism of Fe3O4-TiO2 nanosheets was elucidated, and •OH identified as the primary reactive species responsible for degrading RhB dye. This work provides a novel research direction for designing and preparing advanced catalytic degradation materials, offering a practical solution to the challenging issue of wastewater treatment.

Interfacial construction of 2D Au74Pt23Te3 nanotrough array for boosting alcohol electrooxidation

Two-dimensional (2D) Pt-based multi-metallic nanostructures have been demonstrated to be used as outstanding electrocatalysts for direct alcohol fuel cell owing to the merits of raising electrocatalytic activity and enhancing the durability of catalysts as well as saving Pt utilization. Herein, we develop an interface-confined strategy, achieving 2D close-packed AuPtTe nanotrough array. This strategy involves two steps: (1) assembly of Te nanowires into 2D monolayer array at hexane/water interfaces, and (2) transformation of 2D interfacial Te nanowire array into AuPtTe nanotrough array by interface-confined etching of PtCl62– and AuCl4– in the water subphase. Optimized 2D Au74Pt23Te3 nanotrough array exhibits ∼3.36 and ∼2.15 A mgAu+Pt–1 in the mass activity towards ethanol and methanol electrooxidation, respectively, ∼5 and 3 times that of commercial Pt/C, and shows superior durability to Pt/C, which may be attributed to the synergistic effects of the trough-like morphology and optimal composition. This work may open up a new perspective on the designing of components, morphologies, and compositions of advanced catalysts.

Propolis polyphenol nanosheet for synergistic cancer chemo-photothermal therapy

Two-dimensional (2D) carbon-based nanostructures hold great promise as near-infrared (NIR) photothermal materials, yet their widespread use has been hindered by labor-intensive and costly fabrication processes. Here, a novel, cost-effective approach is presented to produce photothermal materials derived from the polyphenolic fraction of propolis (PFP) for the first time. The method involves the pyrolysis of PFP under a neutral atmosphere, resulting in the formation of 2D PFP-based nanosheets (PFPNS) measuring 50–100 nm in size with efficient photothermal properties. Then, a layer-by-layer nanohybrid structure comprising PFPNS, polydopamine (PDA), mesoporous silica (MS), and polyethyleneimine (PEI) layers (PFPNS@PDA@MS-PEI) was designed as a versatile platform for drug delivery. Specifically, the anticancer drug doxorubicin (DOX) was loaded onto the nanohybrid (PFPNS@PDA@MS(DOX)-PEI) for targeted delivery to cancerous cells. Each layer of the nanohybrid serves a distinct purpose, enhancing functionality and efficacy. The NIR-responsive PFPNS@PDA component facilitates accelerated drug release and induces hyperthermic effects on cancer cells upon NIR irradiation. The MS structure enables high drug loading capacity (approximately 83.3%), while the pH-responsive PEI layer promotes cellular uptake and facilitates drug release within the acidic microenvironment of cancer cells. Combining NIR irradiation with chemotherapy results in a synergistic effect, leading to the eradication of 67% of MCF-7 breast cancer cells. The demonstrated efficacy, coupled with the non-toxic nature of the nanohybrid, positions it as a promising candidate for synergistic chemo-photothermal therapy of tumor tissues.

Continuously Adjustable Thickness of Bi2MoO6 Nanosheets Enhances Photocatalytic Oxidation.

In this study, two-dimensional (2D) nanosheet photocatalysts of Bi2MoO6 with varying thicknesses were synthesized by adjusting the temperature during the hydrothermal reaction. The thinnest Bi2MoO6 nanosheet reached an approximate thickness of ∼4 nm, while the thickest nanosheet measured only ∼16 nm. The photocatalytic performance for Rhodamine B (RhB) degradation was found to be the most effective for the thinnest Bi2MoO6 nanosheet, displaying a degradation rate constant of 0.11 min-1. This rate was 2.5 times higher than that observed for the ∼16 nm thick Bi2MoO6 photocatalyst. The enhanced performance of the thinner two-dimensional nanostructure can be attributed to improved separation and migration of photogenerated charges. Additionally, the study identified hydroxyl radicals (•OH) and superoxide radicals (•O2-) as crucial oxidative species, contributing to the efficient mineralization of RhB dye. This work highlights the controllable synthesis of 2D materials with varying thicknesses and their specific applications in photocatalytic oxidation.

Hydrothermal Synthesis and Characterization of WSe2 Nanosheets: A Promising Approach for Wearable Photodetector Applications.

The two-dimensional (2D) WSe2 nanostructure was successfully synthesized via the hydrothermal method and subjected to comprehensive characterization using various spectroscopic techniques. X-ray diffraction (XRD) analysis confirmed the formation of nanosheets with a hexagonal crystal structure having a space symmetry of P63/mmc. Scanning electron microscopy (SEM) images showed irregular and nonuniform morphology. The size of the 2D nanosheets was determined using transmission electron microscopy (TEM) providing insights intotheir physical characteristics. The optical spectrum analysis yielded a discernible band gap value of 2.1 eV, as determined by the Tauc equation. Photoluminescence (PL) spectra display an emission at a wavelength of 610 nm, showing a broad emission associated with self-trapped excitons. Under excitation at λexc = 360 nm, PL emission spectra displayed a distinct peak at 610 nm, demonstrating the ability of the nanostructure to emit vivid red light. Photometric analysis underscored the potential of this nanostructure as a prominent red-light source for diverse display applications. The optimized photodetection performance of a device showcases a photoresponsivity of approximately 1.25 × 10-3 AW-1 and a detectivity of around 5.19 × 108 Jones at a wavelength of 390 nm. Additionally, the quantum efficiency is reported to be approximately 6.99 × 10-3 at a wavelength of 635 nm. These findings highlight the capability of the device for efficient photoconversion at specified wavelengths, indicating potential applications in sensing, imaging, and optical communication. The combination of structural, morphological, and optical characterizations highlights the suitability of 2D WSe2 nanostructure for practical optoelectronic applications, particularly in display technologies.

Evaluating the effect of unidirectional loading on the piezoresistive characteristics of carbon nanoparticles

The piezoresistive effect of materials can be adopted for a plethora of sensing applications, including force sensors, structural health monitoring, motion detection in fabrics and wearable, etc. Although metals are the most widely adopted material for sensors due to their reliability and affordability, they are significantly affected by temperature. This work examines the piezoresistive performance of carbon nanoparticle (CNP) bulk powders and discusses their potential applications based on strain-induced changes in their resistance and displacement. The experimental results are correlated with the characteristics of the nanoparticles, namely, dimensionality and structure. This report comprehensively characterizes the piezoresistive behavior of carbon black (CB), onion-like carbon (OLC), carbon nanohorns (CNH), carbon nanotubes (CNT), dispersed carbon nanotubes (CNT-D), graphite flakes (GF), and graphene nanoplatelets (GNP). The characterization includes assessment of the ohmic range, load-dependent electrical resistance and displacement tracking, a modified gauge factor for bulk powders, and morphological evaluation of the CNP. Two-dimensional nanostructures exhibit promising results for low loads due to their constant compression-to-displacement relationship. Additionally, GF could also be used for high load applications. OLC’s compression-to-displacement relationship fluctuates, however, for high load it tends to stabilize. CNH could be applicable for both low and high loading conditions since its compression-to-displacement relationship fluctuates in the mid-load range. CB and CNT show the most promising results, as demonstrated by their linear load-resistance curves (logarithmic scale) and constant compression-to-displacement relationship. The dispersion process for CNT is unnecessary, as smaller agglomerates cause fluctuations in their compression-to-displacement relationship with negligible influence on its electrical performance.

Topology selectivity of a conformationally flexible precursor through selenium doping

Conformational arrangements within nanostructures play a crucial role in shaping the overall configuration and determining the properties, for example in covalent/metal organic frameworks. In on-surface synthesis, conformational diversity often leads to uncontrollable or disordered structures. Therefore, the exploration of controlling and directing the conformational arrangements is significant in achieving desired nanoarchitectures. Herein, a conformationally flexible precursor 2,4,6-tris(3-bromophenyl)−1,3,5-triazine is employed, and a random phase consisting of C3h and Cs conformers is firstly obtained after deposition of the precursor on Cu(111) at room temperature to 365 K. At low coverage (0.01 ML) selenium doping, we achieve the selectivity of the C3h conformer and improve the nanopore structural homogeneity. The ordered two-dimensional metal organic nanostructure can be fulfilled by selenium doping from room temperature to 365 K. The formation of the conformationally flexible precursor on Cu(111) is explored through the combination of high-resolution scanning tunneling microscopy and non-contact atomic force microscopy. The regulation of energy diagrams in the absence or presence of the Se atom is revealed by density functional theory calculations. These results can enrich the on-surface synthesis toolbox of conformationally flexible precursors, for the design of complex nanoarchitectures, and for future development of engineered nanomaterials.