Tunable 2D Conjugated Porous Organic Polymer Films for Precise Molecular Nanofiltration and Optoelectronics.

Structural design of 2D conjugated porous organic polymer films (2D CPOPs), by tuning linkage chemistries and pore sizes, provides great adaptability for various applications, including membrane separation. Here, four free-standing 2D CPOP films of imine- or hydrazone-linked polymers (ILP/HLP) in combination with benzene (B-ILP/HLP) and triphenylbenzene (TPB-ILP/HLP) aromatic cores are synthesized. The anisotropic disordered films, composed of polymeric layered structures, can be exfoliated into ultrathin 2D-nanosheets with layer-dependent electrical properties. The bulk CPOP films exhibit structure-dependent optical properties, triboelectric nanogenerator output, and robust mechanical properties, rivaling previously reported 2D polymers and porous materials. The exfoliation energies of the 2D CPOPs and their mechanical behavior at the molecular level are investigated using density function theory (DFT) and molecular dynamics (MD) simulations, respectively. Exploiting the structural tunability, the comparative organic solvent nanofiltration (OSN) performance of six membranes having different pore sizes and linkages to yield valuable trends in molecular weight selectivity is investigated. Interestingly, the OSN performances follow the predicted transport modeling values based on theoretical pore size calculations, signifying the existence of permanent porosity in these materials. The membranes exhibit excellent stability in organic solvents at high pressures devoid of any structural deformations, revealing their potential in practical OSN applications.

Imine-Linked 2D Conjugated Porous Organic Polymer Films for Tunable Acid Vapor Sensing.

Two-dimensional (2D) films of conjugated porous organic polymers (C-POPs) can translate the rich in-plane functionalities of conjugated frameworks into diverse optical and electronic applications while addressing the processability issues of their crystalline analogs for adaptable device architectures. However, the lack of facile single-step synthetic routes to obtain large-area high-quality films of 2D-C-POPs has limited their application possibilities so far. Here, we report the synthesis of four mechanically robust imine-linked 2D-C-POP free-standing films using a single-step fast condensation route that is scalable and tunable. The rigid covalently bonded 2D structures of the C-POP films offer high stability for volatile gas sensing in harsh environments while simultaneously enhancing site accessibility for gas molecules due to mesoporosity by structural design. Structurally, all films were composed of exfoliable layers of 2D polymeric nanosheets (NSs) that displayed anisotropy from disordered stacking, evinced by out-of-plane birefringent properties. The tunable in-plane conjugation, different nitrogen centers, and porous structures allow the films to act as ultraresponsive colorimetric sensors for acid sensing via reversible imine bond protonation. All the films could detect hydrogen chloride (HCl) gas down to 0.05 ppm, far exceeding the Occupational Safety and Health Administration's permissible exposure limit of 5 ppm with fast response time and good recyclability. Computational insights elucidated the effect of conjugation and tertiary nitrogen in the structures on the sensitivity and response time of the films. Furthermore, we exploited the exfoliated large 2D NSs and anisotropic optoelectronic properties of the films to adapt them into micro-optical and triboelectric devices to demonstrate their real-time sensing capabilities.

Cooperative Copper Single-Atom Catalyst in 2D Carbon Nitride for Enhanced CO2 Electrolysis to Methane.

Renewable-electricity-powered carbon dioxide (CO2) reduction (eCO2R) to high-value fuels like methane (CH4) holds the potential to close the carbon cycle at meaningful scales. However, this kinetically staggered 8-electron multistep reduction suffers from inadequate catalytic efficiency and current density. Atomic Cu-structures can boost eCO2R-to-CH4 selectivity due to enhanced intermediate binding energies (BEs) resulting from favorably shifted d-band centers. In this work, 2D carbon nitride (CN) matrices, viz. Na-polyheptazine (PHI) and Li-polytriazine imides (PTI), are exploited to host Cu-N2 type single-atom sites with high density (≈1.5 at%), via a facile metal-ion exchange process. Optimized Cu loading in nanocrystalline Cu-PTI maximizes eCO2R-to-CH4 performance with Faradaic efficiency (FECH4) of ≈68% and a high partial current density of 348 mA cm-2 at -0.84 V vs reversible hydrogen electrode (RHE), surpassing the state-of-the-art catalysts. Multi-Cu substituted N-appended nanopores in the CN frameworks yield thermodynamically stable quasi-dual/triple sites with large interatomic distances dictated by the pore dimensions. First-principles calculations elucidate the relative Cu-CN cooperative effects between the matrices and how the Cu local environment dictates the adsorbate BEs, density of states, and CO2-to-CH4 energy profile landscape. The 9N pores in Cu-PTI yield cooperative Cu-Cu sites that synergistically enhance the kinetics of the rate-limiting steps in the eCO2R-to-CH4 pathway.

Solutions Are the Problem: Ordered Two-Dimensional Covalent Organic Framework Films by Chemical Vapor Deposition.

Covalent organic frameworks (COFs) are a promising class of crystalline polymer networks that are useful due to their high porosity, versatile functionality, and tunable architecture. Conventional solution-based methods of producing COFs are marred by slow reactions that produce powders that are difficult to process into adaptable form factors for functional applications, and there is a need for facile and fast synthesis techniques for making crystalline and ordered covalent organic framework (COF) thin films. In this work, we report a chemical vapor deposition (CVD) approach utilizing co-evaporation of two monomers onto a heated substrate to produce highly crystalline, defect-free COF films and coatings with hydrazone, imine, and ketoenamine COF linkages. This all-in-one synthesis technique produces highly crystalline, 40 nm-1 µm-thick COF films on Si/SiO2 substrates in less than 30 min. Crystallinity and alignment were proven by using a combination of grazing-incidence wide-angle X-ray scattering (GIWAXS) and transmission electron microscopy (TEM), and successful conversion of the monomers to produce the target COF was supported by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV-vis measurements. Additionally, we used atomic force microscopy (AFM) to investigate the growth mechanisms of these films, showing the coalescence of triangular crystallites into a smooth film. To show the wide applicability and scope of the CVD process, we also prepared crystalline ordered COF films with imine and ketoenamine linkages. These films show potential as high-quality size exclusion membranes, catalytic platforms, and organic transistors.

Synthesis and Additive Manufacturing of Hydrazone-Linked Covalent Organic Framework Aerogels.

Covalent Organic Frameworks (COFs) are crystalline, porous organic materials. Recent studies have demonstrated novel processing strategies for COFs to form adaptable architectures, but these have focused primarily on imine-linked COFs. This work presents a new synthesis and processing route to produce crystalline hydrazone-linked COF gels and aerogels with hierarchical porosity. The method was implemented to produce a series of hydrazone-linked COFs with different alkyl side-chain substituents, achieving control of the hydrophilicity of the final aerogel. Variation in the length of the alkyl substituents yielded materials with controllable form factors that can preferentially adsorb water or nonpolar organic solvents. Additionally, a method for additive manufacturing of hydrazone-linked COFs using hydroxymethylcellulose as a sacrificial additive is presented. This work demonstrates an effective and simple approach to the fabrication of hydrazone COF aerogels and additive manufacturing to produce hydrazone COFs of desired shape.

A Researcher's Perspective on Unconventional Lab-to-Fab for 2D Semiconductor Devices.

Current silicon technology is on the verge of reaching its performance limits. This aspect, coupled with the global chip shortage, makes a solid case for steering our attention toward the accelerated commercialization of other electronic materials. Among the available suite of emerging electronic materials, two-dimensional materials, including transition metal dichalcogenides (TMDs), exhibit improved short-channel effects, high electron mobility, and integration into CMOS-compatible processing. While these materials may not be able to replace silicon at the current stages of development, they can supplement Si in the form of Si-compatible CMOS processing and be manufactured for tailored applications. However, the major hurdle in the path of commercialization of such materials is the difficulty in producing their wafer-scale forms, which are not necessarily single crystalline but on a large scale. Recent but exploratory interest in 2D materials from industries, such as TSMC, necessitates an in-depth analysis of their commercialization potential based on trends and progress in entrenched electronic materials (Si) and ones with a short-term commercialization potential (GaN, GaAs). We also explore the possibility of unconventional fabrication techniques, such as printing, for 2D materials becoming more mainstream and being adopted by industries in the future. In this Perspective, we discuss aspects to optimize cost, time, thermal budget, and a general pathway for 2D materials to achieve similar milestones, with an emphasis on TMDs. Beyond synthesis, we propose a lab-to-fab workflow based on recent advances that can operate on a low budget with a mainstream full-scale Si fabrication unit.

Enhancing the Electrode Gravimetric Capacity of Li1.2Mn0.4Ti0.4O2 Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation.

Mn-based cation-disordered rocksalt oxides (Mn-DRX) are emerging as promising cathode materials for next-generation Li-ion batteries due to their high specific capacities and cobalt- and nickel-free characteristic. However, to reach the usable capacity, solid-state synthesized Mn-DRX materials require activation via postsynthetic ball milling, typically incorporating more than 20 wt % conductive carbon that adversely reduces the electrode-level gravimetric capacity. To address this issue, we first deposit amorphous carbon on the surface of the Li1.2Mn0.4Ti0.4O2 (LMTO) particles to increase the electrical conductivity by 5 orders of magnitude. Although the cathode material gravimetric first charge capacity reaches 180 mAh/g, its highly irreversible behavior leads to a first discharge capacity of 70 mAh/g. Subsequently, to ensure a good electrical percolation network, the LMTO material is ball-milled with a multiwall carbon nanotube (CNT) to obtain a 78.7 wt % LMTO active material loading in the cathode electrode (LMTO-CNT). As a result, a 210 mAh/g cathode electrode gravimetric first charge and 165 mAh/g first discharge capacity values are obtained, compared to the respective capacity values of 222 and 155 mAh/g for the LMTO material ball-milled with 20 wt % SuperP C65 electrode (LMTO-SP). After 50 cycles, LMTO-CNT delivers a 121 mAh/g electrode gravimetric discharge capacity, largely outperforming the value of 44 mAh/g of LMTO-SP. Our study demonstrates that while ball milling is necessary to achieve a significant amount of capacity of LMTO, a careful selection of additives, such as CNT, effectively reduces the required carbon quantity to achieve a higher electrode gravimetric discharge capacity.

Spontaneous hydrogen production using gadolinium telluride.

Developing materials for controlled hydrogen production through water splitting is one of the most promising ways to meet current energy demand. Here, we demonstrate spontaneous and green production of hydrogen at high evolution rate using gadolinium telluride (GdTe) under ambient conditions. The spent materials can be reused after melting, which regain the original activity of the pristine sample. The phase formation and reusability are supported by the thermodynamics calculations. The theoretical calculation reveals ultralow activation energy for hydrogen production using GdTe caused by charge transfer from Te to Gd. Production of highly pure and instantaneous hydrogen by GdTe could accelerate green and sustainable energy conversion technologies.

Functionality Tuning in Hierarchically Engineered Magnetoelectric Nanocomposites for Energy-Harvesting Applications.

The ß-phase of the copolymer poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) possesses the highest dipole moment among all the functional polymers. It remains a key component of flexible energy-harvesting devices based on piezoelectricity and triboelectricity in the last decade. However, the quest for P(VDF-TrFE)-based magnetoelectric (ME) nanocomposites with enhanced ferroelectric, piezoelectric, and triboelectric properties remains elusive. The magnetostrictive inclusion in the copolymer matrix forms electrically conducting pathways and degrades ß-phase crystallinity significantly, deteriorating the functional properties of the nanocomposite films. To address this issue, we report the synthesis of magnetite (Fe3O4) nanoparticles on micron-scale magnesium hydroxide [Mg(OH)2] templates. These hierarchical structures were incorporated within the P(VDF-TrFE) matrix rendering composites with enhanced energy-harvesting capability. The Mg(OH)2 template prevents the formation of a continuous network of magnetic fillers, leading to lower electrical leakage in the composite. The addition of dual-phase fillers with 5 wt % only increases remanent polarization (Pr) values by ∼44%, owing to the presence of the ß-phase with significant crystallinity and increased interfacial polarization. The composite film exhibits a quasi-superparamagnetic nature and a significant magnetoelectric coupling coefficient (αME) of 30 mV/cm Oe. The film was also employed for triboelectric nanogenerator applications, exhibiting five times higher power density than the pristine film. We finally explored the integration of our ME devices with an internet of things platform to monitor the operational status of electrical appliances remotely. In light of these findings, the present work opens the path for future self-powered, multifunctional, and flexible ME devices with new application domains.

Bifunctional Gas Diffusion Electrode Enables In Situ Separation and Conversion of CO2 to Ethylene from Dilute Stream.

The requirement of concentrated carbon dioxide (CO2 ) feedstock significantly limits the economic feasibility of electrochemical CO2 reduction (eCO2 R) which often involves multiple intermediate processes, including CO2 capture, energy-intensive regeneration, compression, and transportation. Herein, a bifunctional gas diffusion electrode (BGDE) for separation and eCO2 R from a low-concentration CO2 stream is reported. The BGDE is demonstrated for the selective production of ethylene (C2 H4 ) by combining high-density-polyethylene-derived porous carbon (HPC) as a physisorbent with polycrystalline copper as a conversion catalyst. The BGDE shows substantial tolerance to 10 vol% CO2 exhibiting a Faradaic efficiency of ≈45% toward C2 H4 at a current density of 80 mA cm-2 , outperforming previous reports that utilized such partial pressure (PCO2 = 0.1 atm and above) and unaltered polycrystalline copper. Molecular dynamics simulation and mixed gas permeability assessment reveal that such selective performance is ensured by high CO2 uptake of the microporous HPC as well as continuous desorption owing to the molecular diffusion and concentration gradient created by the binary flow of CO2 and nitrogen (CO2 |N2 ) within the sorbent boundary. Based on detailed techno-economic analysis, it is concluded that this in situ process can be economically compelling by precluding the C2 H4 production cost associated with the energy-intensive intermediate steps of the conventional decoupled process.

High-Density Cobalt Single-Atom Catalysts for Enhanced Oxygen Evolution Reaction.

Single atom catalysts (SACs) possess unique catalytic properties due to low-coordination and unsaturated active sites. However, the demonstrated performance of SACs is limited by low SAC loading, poor metal-support interactions, and nonstable performance. Herein, we report a macromolecule-assisted SAC synthesis approach that enabled us to demonstrate high-density Co single atoms (10.6 wt % Co SAC) in a pyridinic N-rich graphenic network. The highly porous carbon network (surface area of ∼186 m2 g-1) with increased conjugation and vicinal Co site decoration in Co SACs significantly enhanced the electrocatalytic oxygen evolution reaction (OER) in 1 M KOH (η10 at 351 mV; mass activity of 2209 mA mgCo-1 at 1.65 V) with more than 300 h stability. Operando X-ray absorption near-edge structure demonstrates the formation of electron-deficient Co-O coordination intermediates, accelerating OER kinetics. Density functional theory (DFT) calculations reveal the facile electron transfer from cobalt to oxygen species-accelerated OER.

Sustainable valorization of asphaltenes via flash joule heating.

The refining process of petroleum crude oil generates asphaltenes, which poses complicated problems during the production of cleaner fuels. Following refining, asphaltenes are typically combusted for reuse as fuel or discarded into tailing ponds and landfills, leading to economic and environmental disruption. Here, we show that low-value asphaltenes can be converted into a high-value carbon allotrope, asphaltene-derived flash graphene (AFG), via the flash joule heating (FJH) process. After successful conversion, we develop nanocomposites by dispersing AFG into a polymer effectively, which have superior mechanical, thermal, and corrosion-resistant properties compared to the bare polymer. In addition, the life cycle and technoeconomic analysis show that the FJH process leads to reduced environmental impact compared to the traditional processing of asphaltene and lower production cost compared to other FJH precursors. Thus, our work suggests an alternative pathway to the existing asphaltene processing that directs toward a higher value stream while sequestering downstream emissions from the processing.

Structure-Tailored Surface Oxide on Cu-Ga Intermetallics Enhances CO2 Reduction Selectivity to Methanol at Ultralow Potential.

Electrochemical CO2 reduction reaction (eCO2 RR) is performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9 Ga4 ). Among them, CuGa2 selectively converts CO2 to methanol with remarkable Faradaic efficiency of 77.26% at an extremely low potential of -0.3 V vs RHE. The high performance of CuGa2 compared to Cu9 Ga4 is driven by its unique 2D structure, which retains surface and subsurface oxide species (Ga2 O3 ) even in the reduction atmosphere. The Ga2 O3 species is mapped by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) techniques and electrochemical measurements. The eCO2 RR selectivity to methanol are decreased at higher potential due to the lattice expansion caused by the reduction of the Ga2 O3 , which is probed by in situ XAFS, quasi in situ powder X-ray diffraction, and ex situ XPS measurements. The mechanism of the formation of methanol is visualized by in situ infrared (IR) spectroscopy and the source of the carbon of methanol at the molecular level is confirmed from the isotope-labeling experiments in presence of 13 CO2 . Finally, to minimize the mass transport limitations and improve the overall eCO2 RR performance, a poly(tetrafluoroethylene)-based gas diffusion electrode is used in the flow cell configuration.

Preclinical stage abundance and nuclear antigen reactivity of faecal Immunoglobulin A vary among males and females of lupus-prone mouse models.

Systemic lupus erythematosus (SLE) is characterized by the production of pathogenic autoantibodies with nuclear antigen (nAg) specificity. Using (SWRxNZB)F1 (SNF1) mice, we showed higher levels of Immunoglobulin A (IgA) production in the intestine and the nAg reactivity of faecal IgA under lupus susceptibility. Here, we determined whether the faecal IgA abundance and nAg reactivity are higher in, different among, various lupus-prone preclinical models (MRL/lpr, NZBxNZW-F1, SNF1, NZM2410 and NZM2328). We also determined whether the faecal IgA nAg reactivity at preseropositive ages correlates with the eventual serum autoantibody levels in males and females of these mouse models. We show that age-dependent increase in the abundance and nAg reactivity of faecal IgA can vary among different lupus-prone mouse models. Importantly, faecal IgA in these mice show significant levels of nAg reactivity, starting as early as at juvenile age. Furthermore, the pre-seropositive stage nAg reactivity of faecal IgA in most lupus-prone strains correlates well with that of eventual, seropositive stage systemic autoantibody levels. Gender differences in serum autoantibody levels were preceded by similar differences in the faecal IgA abundance and nAg reactivity. These observations suggest that faecal IgA features, nAg reactivity particularly, could serve as a biomarker for early prediction of the eventual systemic autoimmunity in lupus-prone subjects.

High-Strength, Microporous, Two-Dimensional Polymer Thin Films with Rigid Benzoxazole Linkage.

Two-dimensional (2D) rigid polymers provide an opportunity to translate the high-strength, high-modulus mechanical performance of classic rigid-rod 1D polymers across a plane by extending covalent bonding into two dimensions while simultaneously reducing density due to microporosity by structural design. Thus far, this potential has remained elusive because of the challenge of producing high-quality 2D polymer thin films, particularly those with irreversible, rigid benzazole linkages. Here, we present a facile two-step process that allows the deposition of a uniform intermediate film network via reversible, non-covalent interactions, followed by a subsequent solid-state annealing step that facilitates the irreversible conversion to a 2D covalently bonded polymer product with benzoxazole linkages. We demonstrate the versatility of this synthesis method by producing films with four different aromatic core units. The resulting films show microporosity and anisotropy with a 2D layered structure that can be exfoliated into few-layer nanosheets using a freeze-thaw method. These films have promising mechanical properties with an in-plane ultimate tensile strength of nearly 40 MPa and axial tensile and transverse compressive elastic moduli on the scale of several GPa, rivaling the performance of solution-cast films of 1D polybenzoxazole, as well as several other 1D high-strength polymer films.

Amine-Functionalized Carbon Nanodot Electrocatalysts Converting Carbon Dioxide to Methane.

The electrochemical conversion of carbon dioxide (CO2 ) to methane (CH4 ), which can be used not only as fuel but also as a hydrogen carrier, has drawn great attention for use in supporting carbon capture and utilization. The design of active and selective electrocatalysts with exceptional CO2 -to-CH4 conversion efficiency is highly desirable; however, it remains a challenge. Here a molecular tuning strategy-in situ amine functionalization of nitrogen-doped graphene quantum dots (GQDs) for highly efficient CO2 -to-CH4 conversion is presented. Amine functionalized nitrogen-doped GQDs achieve a CH4 Faradic efficiency (FE) of 63% and 46%, respectively, at CH4 partial current densities of 170 and 258 mA cm-2 , approximating to or even outperforming state-of-the-art Cu-based electrocatalysts. These GQDs also convert CO2 to C2 products mainly including C2 H4 and C2 H5 OH with a maximum FE of ≈10%. A systematic analysis reveals that the CH4 yield varies linearly with amine group content, whereas the C2 production rate is positively dependent on pyridinic N dopant content. This work provides insight into the rational design of carbon catalysts with CO2 -to-CH4 conversion efficiency at the industrially relevant level.

Corrosion Resistance of Sulfur-Selenium Alloy Coatings.

Despite decades of research, metallic corrosion remains a long-standing challenge in many engineering applications. Specifically, designing a material that can resist corrosion both in abiotic as well as biotic environments remains elusive. Here a lightweight sulfur-selenium (S-Se) alloy is designed with high stiffness and ductility that can serve as an excellent corrosion-resistant coating with protection efficiency of ≈99.9% for steel in a wide range of diverse environments. S-Se coated mild steel shows a corrosion rate that is 6-7 orders of magnitude lower than bare metal in abiotic (simulated seawater and sodium sulfate solution) and biotic (sulfate-reducing bacterial medium) environments. The coating is strongly adhesive, mechanically robust, and demonstrates excellent damage/deformation recovery properties, which provide the added advantage of significantly reducing the probability of a defect being generated and sustained in the coating, thus improving its longevity. The high corrosion resistance of the alloy is attributed in diverse environments to its semicrystalline, nonporous, antimicrobial, and viscoelastic nature with superior mechanical performance, enabling it to successfully block a variety of diffusing species.

Structure, Properties and Applications of Two-Dimensional Hexagonal Boron Nitride.

Hexagonal boron nitride (h-BN) has emerged as a strong candidate for two-dimensional (2D) material owing to its exciting optoelectrical properties combined with mechanical robustness, thermal stability, and chemical inertness. Super-thin h-BN layers have gained significant attention from the scientific community for many applications, including nanoelectronics, photonics, biomedical, anti-corrosion, and catalysis, among others. This review provides a systematic elaboration of the structural, electrical, mechanical, optical, and thermal properties of h-BN followed by a comprehensive account of state-of-the-art synthesis strategies for 2D h-BN, including chemical exfoliation, chemical, and physical vapor deposition, and other methods that have been successfully developed in recent years. It further elaborates a wide variety of processing routes developed for doping, substitution, functionalization, and combination with other materials to form heterostructures. Based on the extraordinary properties and thermal-mechanical-chemical stability of 2D h-BN, various potential applications of these structures are described.

Healing of Ocular Herpetic Disease Following Treatment With an Engineered FGF-1 Is Associated With Increased Corneal Anti-Inflammatory M2 Macrophages.

Herpes simplex virus 1 (HSV-1) infects the cornea and caused blinding ocular disease. In the present study, we evaluated whether and how a novel engineered version of fibroblast growth factor-1 (FGF-1), designated as TTHX1114, would reduce the severity of HSV-1-induced and recurrent ocular herpes in the mouse model. The efficacy of TTHX1114 against corneal keratopathy was assessed in B6 mice following corneal infection with HSV-1, strain McKrae. Starting day one post infection (PI), mice received TTHX1114 for 14 days. The severity of primary stromal keratitis and blepharitis were monitored up to 28 days PI. Inflammatory cell infiltrating infected corneas were characterized up to day 21 PI. The severity of recurrent herpetic disease was quantified in latently infected B6 mice up to 30 days post-UVB corneal exposure. The effect of TTHX1114 on M1 and M2 macrophage polarization was determined in vivo in mice and in vitro on primary human monocytes-derived macrophages. Compared to HSV-1 infected non-treated mice, the infected and TTHX1114 treated mice exhibited significant reduction of primary and recurrent stromal keratitis and blepharitis, without affecting virus corneal replication. The therapeutic effect of TTHX1114 was associated with a significant decrease in the frequency of M1 macrophages infiltrating the cornea, which expressed significantly lower levels of pro-inflammatory cytokines and chemokines. This polarization toward M2 phenotype was confirmed in vitro on human primary macrophages. This pre-clinical finding suggests use of this engineered FGF-1 as a novel immunotherapeutic regimen to reduce primary and recurrent HSV-1-induced corneal disease in the clinic.

Structural Defects Modulate Electronic and Nanomechanical Properties of 2D Materials.

Two-dimensional materials such as graphene and molybdenum disulfide are often subject to out-of-plane deformation, but its influence on electronic and nanomechanical properties remains poorly understood. These physical distortions modulate important properties which can be studied by atomic force microscopy and Raman spectroscopic mapping. Herein, we have identified and investigated different geometries of line defects in graphene and molybdenum disulfide such as standing collapsed wrinkles, folded wrinkles, and grain boundaries that exhibit distinct strain and doping. In addition, we apply nanomechanical atomic force microscopy to determine the influence of these defects on local stiffness. For wrinkles of similar height, the stiffness of graphene was found to be higher than that of molybdenum disulfide by 10-15% due to stronger in-plane covalent bonding. Interestingly, deflated graphene nanobubbles exhibited entirely different characteristics from wrinkles and exhibit the lowest stiffness of all graphene defects. Density functional theory reveals alteration of the bandstructures of graphene and MoS2 due to the wrinkled structure; such modulation is higher in MoS2 compared to graphene. Using this approach, we can ascertain that wrinkles are subject to significant strain but minimal doping, while edges show significant doping and minimal strain. Furthermore, defects in graphene predominantly show compressive strain and increased carrier density. Defects in molybdenum disulfide predominantly show tensile strain and reduced carrier density, with increasing tensile strain minimizing doping across all defects in both materials. The present work provides critical fundamental insights into the electronic and nanomechanical influence of intrinsic structural defects at the nanoscale, which will be valuable in straintronic device engineering.