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In this study, five kinds of 1-alkyl-3-methylimidazolium bromide ([C X ami]Br) ionic liquids with different alkyl chain lengths (8, 10, 12, 14, and 16) were selected as inhibitors. Then, their corrosion inhibition performances for Q235 steel in 1.0 mol L -1 HCl solution were investigated via a weight loss test, polarization curve method, and surface analysis techniques. The results show that these five imidazolium-based ionic liquids are all mixed-type inhibitors, and they can be spontaneously adsorbed onto the Q235 steel surface. The adsorption process follows the Langmuir model and involves mixed physical-chemical adsorption. Theoretical calculations confirm that the increase in alkyl chain length is conducive to the imidazolium-based ionic liquids exhibiting stronger chemical bonding abilities and forming denser adsorption films. The inhibition efficiency significantly increases below the critical micelle concentration (CMC) with an increase in alkyl chain length, and the highest inhibition efficiency is 95.17% for the [C 16 ami]Br inhibitor at the concentration of 0.005 mM. However, above the CMC, the inhibition efficiency is minimally affected by the alkyl chain length since all ionic liquid inhibitors have reached adsorption saturation on the steel surface.

Molecular motors (MM) are molecular machines, or nanomachines, that rotate unidirectionally upon photostimulation and perform mechanical work on their environment. In the last several years, it has been shown that the photomechanical action of MM can be used to permeabilize lipid bilayers, thereby killing cancer cells and pathogenic microorganisms and controlling cell signaling. The work contributes to a growing acknowledgement that the molecular actuation characteristic of these systems is useful for various applications in biology. However, the mechanical effects of molecular motion on biological materials are difficult to disentangle from photodynamic and photothermal action, which are also present when a light-absorbing fluorophore is irradiated with light. Here, an overview of the key methods used by various research groups to distinguish the effects of photomechanical, photodynamic, and photothermal action is provided. It is anticipated that this discussion will be helpful to the community seeking to use MM to develop new and distinctive medical technologies that result from mechanical disruption of biological materials., (© 2023 Wiley-VCH GmbH.)

Hemp is known for its swift growth and remarkable sustainability, requiring significantly less water, an adaptable cultivation to a wide range of climates when compared to other fibers sources, making it a practical and environmentally friendly choice for packaging materials. The current research seeks to extract cellulose nanocrystals (CNCs) from hemp fibers using alkali treatment followed by acid hydrolysis and assess their reinforcing capacity in polyvinyl alcohol (PVA) and chitosan (CS) films. AFM analysis confirmed the existence of elongated, uniquely nanosized CNC fibers. The length of the isolated CNCs was approximately 277.76 ± 61 nm, diameter was 6.38 ± 1.27 nm and its aspect ratio was 44.69 ± 11.08. The FTIR and SEM analysis indicated the successful removal of non-cellulosic compounds. Furthermore, the study explored the impact of adding CNCs at varying weight percentages (0, 0.5, 1, 2.5, and 5 wt%) as a strengthening agent on the chemical composition, structure, tensile characteristics, transparency, and water solubility of the bionanocomposite films. Adding CNCs to the CS/PVA film, up to 5 wt%, resulted in an improvement in both the Young's modulus and tensile strength of the bionanocomposite film, which are measured at (412.46 ± 10.49 MPa) and (18.60 ± 3.42 MPa), respectively, in contrast to the control films with values of (202.32 ± 22.50 MPa) and (13.72 ± 2.61 MPa), respectively. The scanning electron microscopy (SEM) images reveal the creation of a CS/PVA/CNC film that appears smooth, with no signs of clumping or clustering. The blending and introduction of CNCs have yielded transparent and biodegradable CS/PVA films. This incorporation has led to a reduction in the gas transmission rate (from 7.013 to 4.159 cm 3 (m 2 day·0.1 MPa)) -1 , a decrease in transparency (from 90.23% to 82.47%), and a lowered water solubility (from 48% to 33%). This study is the inaugural effort to propose the utilization of hemp-derived CNC as a strengthening component in the development of mechanically robust and transparent CS/PVA-CNC bio-nanocomposite films, holding substantial potential for application in the field of food packaging., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Monolayer graphene with nanometre-scale pores, atomically thin thickness and remarkable mechanical properties provides wide-ranging opportunities for applications in ion and molecular separations 1 , energy storage 2 and electronics 3 . Because the performance of these applications relies heavily on the size of the nanopores, it is desirable to design and engineer with precision a suitable nanopore size with narrow size distributions. However, conventional top-down processes often yield log-normal distributions with long tails, particularly at the sub-nanometre scale 4 . Moreover, the size distribution and density of the nanopores are often intrinsically intercorrelated, leading to a trade-off between the two that substantially limits their applications 5-9 . Here we report a cascaded compression approach to narrowing the size distribution of nanopores with left skewness and ultrasmall tail deviation, while keeping the density of nanopores increasing at each compression cycle. The formation of nanopores is split into many small steps, in each of which the size distribution of all the existing nanopores is compressed by a combination of shrinkage and expansion and, at the same time as expansion, a new batch of nanopores is created, leading to increased nanopore density by each cycle. As a result, high-density nanopores in monolayer graphene with a left-skewed, short-tail size distribution are obtained that show ultrafast and ångström-size-tunable selective transport of ions and molecules, breaking the limitation of the conventional log-normal size distribution 9,10 . This method allows for independent control of several metrics of the generated nanopores, including the density, mean diameter, standard deviation and skewness of the size distribution, which will lead to the next leap in nanotechnology., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Intercellular calcium waves (ICW) are complex signalling phenomena that control many essential biological activities, including smooth muscle contraction, vesicle secretion, gene expression and changes in neuronal excitability. Accordingly, the remote stimulation of ICW could result in versatile biomodulation and therapeutic strategies. Here we demonstrate that light-activated molecular machines (MM)-molecules that perform mechanical work on the molecular scale-can remotely stimulate ICW. MM consist of a polycyclic rotor and stator that rotate around a central alkene when activated with visible light. Live-cell calcium-tracking and pharmacological experiments reveal that MM-induced ICW are driven by the activation of inositol-triphosphate-mediated signalling pathways by unidirectional, fast-rotating MM. Our data suggest that MM-induced ICW can control muscle contraction in vitro in cardiomyocytes and animal behaviour in vivo in Hydra vulgaris. This work demonstrates a strategy for directly controlling cell signalling and downstream biological function using molecular-scale devices., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Nontrivial polarization textures have been demonstrated in ferroelectric/dielectric superlattices, where the electrostatic, elastic, and different gradient energies compete in a delicate balance. When PbTiO 3 /SrTiO 3 superlattices are grown on DyScO 3 , the coexistence of ferroelectric domains and vortex structure is observed for n = 12-20 unit cells. Here, we report an approach to achieve single-phase vortex structures in superlattices by controlling the epitaxial strain using Sr 1.04 Al 0.12 Ga 0.35 Ta 0.50 O 3 substrates. The domain width follows Kittel's law with the thickness of the ferroelectric PbTiO 3 layers. A phase transition from vortex to a disordered phase with temperature is characterized by the correlation length. Resonant soft X-ray diffraction circular dichroism at the titanium L -edge reveals enhanced chirality with the thickness of the ferroelectric layer. These results are supported by second-principles simulations, which demonstrate that the integrated helicity increases with n . The stabilization of chiral single-phase polar vortices in ferroelectric/dielectric superlattices can enable novel optoelectronic devices with enhanced ferroelectric-light interaction.

Despite extensive studies on size effects in ferroelectrics, how structures and properties evolve in antiferroelectrics with reduced dimensions still remains elusive. Given the enormous potential of utilizing antiferroelectrics for high-energy-density storage applications, understanding their size effects will provide key information for optimizing device performances at small scales. Here, the fundamental intrinsic size dependence of antiferroelectricity in lead-free NaNbO 3 membranes is investigated. Via a wide range of experimental and theoretical approaches, an intriguing antiferroelectric-to-ferroelectric transition upon reducing membrane thickness is probed. This size effect leads to a ferroelectric single-phase below 40 nm, as well as a mixed-phase state with ferroelectric and antiferroelectric orders coexisting above this critical thickness. Furthermore, it is shown that the antiferroelectric and ferroelectric orders are electrically switchable. First-principle calculations further reveal that the observed transition is driven by the structural distortion arising from the membrane surface. This work provides direct experimental evidence for intrinsic size-driven scaling in antiferroelectrics and demonstrates enormous potential of utilizing size effects to drive emergent properties in environmentally benign lead-free oxides with the membrane platform., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

This study focused on the production and characterization of phosphate glass fibers (PGF) for application as composite reinforcement. Phosphate glasses belonging to the system 52P 2 O 5 24CaO13MgO (11-(X + Y)) K 2 OXFe 2 O 3 YTiO 2 (X:1, 3, 5) and (Y:0.5, 1) were elaborated and converted to phosphate glass fibers. First, their mechanical properties and chemical durability were investigated. Then, the optimized PGF compositions were used afterward as reinforcement for thermosetting composite materials. Polyester matrices reinforced with short phosphate glass fibers (sPGF) up to 20 wt % were manufactured by the contact molding process. The mechanical and morphological properties of different sPGF-reinforced polyester systems were evaluated. The choice between the different phosphate-based glass syntheses (PGFs) was determined by their superior mechanical performance, their interesting chemical durability, and their high level of dispersion in the polyester matrix without any ad sizing as proven by SEM morphological analysis. Moreover, the characterization of mechanical properties revealed that the tensile and flexural moduli of the developed polyester-based composites were improved by increasing the sPGF content in the polymer matrix in perfect agreement with Takayanagi model predictions. The present work thus highlights some promising results to obtain high-quality phosphate glass fiber-reinforced polyester parts which can be transposed to other thermosetting or thermoplastic-based composites for high-value applications.

Advances in nanoscience have enabled the synthesis of nanomaterials, such as graphene, from low-value or waste materials through flash Joule heating. Though this capability is promising, the complex and entangled variables that govern nanocrystal formation in the Joule heating process remain poorly understood. In this work, machine learning (ML) models are constructed to explore the factors that drive the transformation of amorphous carbon into graphene nanocrystals during flash Joule heating. An XGBoost regression model of crystallinity achieves an r 2 score of 0.8051 ± 0.054. Feature importance assays and decision trees extracted from these models reveal key considerations in the selection of starting materials and the role of stochastic current fluctuations in flash Joule heating synthesis. Furthermore, partial dependence analyses demonstrate the importance of charge and current density as predictors of crystallinity, implying a progression from reaction-limited to diffusion-limited kinetics as flash Joule heating parameters change. Finally, a practical application of the ML models is shown by using Bayesian meta-learning algorithms to automatically improve bulk crystallinity over many Joule heating reactions. These results illustrate the power of ML as a tool to analyze complex nanomanufacturing processes and enable the synthesis of 2D crystals with desirable properties by flash Joule heating., (© 2022 Wiley-VCH GmbH.)

Solar-assisted electrochemical desalination has offered a new energy-water nexus technology for sustainable development in recent studies. However, only a few reports have demonstrated insufficient photocurrent, a low salt removal rate, and poor stability. In this study, a high-quality freshwater level of 5-10 ppm (from an initial feed of 10 000 ppm), an enhanced salt removal rate (217.8 µg cm -2 min -1 of NaCl), and improved cycling and long-term stability are achieved by integrating dye-sensitized solar cells (DSSCs) and redox-flow desalination (RFD) under light irradiation without additional electrical energy consumption. The DSSC redox electrolyte (I - /I 3 - ) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy-water nexus technology will open a new route for dual-role devices with photodesalination functions without energy consumption and solar-to-electricity generation.2 ) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy-water nexus technology will open a new route for dual-role devices with photodesalination functions without energy consumption and solar-to-electricity generation., (© 2021 Wiley-VCH GmbH.)

Functionalized carbon nanospheres have been synthesized in situ via a facile chemical vapor deposition strategy, fabricated by the pyrolysis of toluene/ethanol mixtures at different percentages (0, 1, 2, 3, 4, and 5 wt% of ethanol). The as-grown nanospheres have been characterized using transmission electron microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopy, x-ray diffraction, nitrogen adsorption, zeta potential measurements and x-ray photoelectron spectroscopy. Results indicate that the incorporation of ethanol in the precursor solution reflected in the presence of oxygen and hydrogen functional groups, the highest functionalized nanospheres without compromising the morphology of the sample were yielded at 3 wt% concentration. These in situ added functional groups rendered the carbon nanostructures enhancedly dispersible and stable in water, avoiding post-synthesis and harsh chemicals processing; envisaging thus applications of the nanospheres in the biomedical field where hydrophilicity of the nanomaterials is mandatory.

Fiber-reinforced polymers have emerged as one of the most popular methods to improve the polymers' characteristics owing to their prominent properties. This study aimed to investigate the properties of cellulose microfibers (CMF), cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) extracted from hemp stalks, then their effect as reinforcement for the PVA-polymer. CMF have been extracted from hemp stalks with a diameter and yield of 16.96 μm and 63 %, respectively. Needle-shaped CNC were obtained from CMF using sulfuric acid hydrolysis at two hydrolysis times, while CNF exhibited a web-like structure obtained using TEMPO-oxidation followed by mechanical treatment. Cellulose derivatives were utilized to develop cellulose-based PVA composites; their transparency, chemical structure, thermal stability and mechanical properties were investigated. The incorporation of nanocellulose demonstrated a significant increase in mechanical properties compared to the neat PVA. The extracted nanocellulose could be used as nanofillers for the preparation of transparent and mechanically strong PVA-based nanocomposites., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Biosorption using natural waste has emerged as a potential and promising strategy for removal of toxic dyes from wastewaters in comparison to conventional ones. Herein, the Codium decorticatum alga (CDA) was biologically identified and used as a biosorbent for anionic and cationic dyes from aqueous solutions. SEM analysis showed a rough surface with an irregular edge and shape while hydroxyl, amine, sulfur and carboxyl functional groups were identified using FTIR analysis. TGA/DTG confirmed the stability of CDA and the adsorption process. Batch studies were conducted to investigate the effect of operational factors such as initial pH, biosorbent dosage, temperature, initial concentration, and solid/liquid contact time on the biosorption of crystal violet (CV) and Congo red (CR) dyes. For both CV and CR dyes, the biosorption kinetics was accurately described by the pseudo-second-order model and the Langmuir isotherm was found to be best fitted for equilibrium data. Maximum uptake capacities have attained up to 278.46 mg/g for CV and 191.01 mg/g for CR. The CV and CR dye biosorption mechanism was ultimately manifested through the electrostatic interactions. The regeneration study showed that the CDA presents excellent reuse performance up to four consecutive cycles. The process optimization was performed using the response surface methodology based on Box-Behnken design (RSM-BDD). Accordingly, the optimum predicted removal efficiencies using RSM-BBD for CV and CR were obtained, respectively, at 96.9 and 89.8% using a CDA dose of 1.5 g/L, dye concentration of 20 mg/L, pH of 10 for CV, and pH of 4 for CR. Overall, CDA behaves as an efficient, recyclable, cheap, and eco-friendly adsorbent for cleaning-up of dyed effluents., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

In this study, sulfated and carboxylated cellulose nanocrystals (CNC) have been produced from newly identified cellulose-rich bio-sourced material, namely Juncus plant. The Juncus plant stems were firstly subjected to chemical treatments to produce purified cellulose microfibers (CMF) with an average diameter of 3.5 µm and yield of 36%. By subjecting CMF to sulfuric and citric/hydrochloric mixture acids hydrolysis, sulfated CNC (S-CNC) and carboxylated CNC (C-CNC) have been produced with a diameter of 7.3 ± 2.2 and 6.1 ± 2.8 nm, and a length of 431 ± 94 and 352 ± 79 nm, respectively. These newly extracted S-CNC and C-CNC exhibited a crystallinity of 81% and 83% with cellulose I structure and showed high thermal stability (>200 °C). Herein, this newly identified Juncus plant, which is a naturally-derived source, could be used as a valuable alternative to conventional sources such as wood and cotton for nanocellulose production. We speculate that the determined high thermal stability, the large aspect ratio and high crystallinity will allow the use of the extracted CNC as nano-reinforcing agents in polymers that require processing temperatures of up to 200 °C. Owing to their surface functionalities (sulfated or carboxylated surface groups), the here produced CNC could be used as nano-additives or nano-reinforcing agents for water-soluble bio-polymers in order to produce bio-nanocomposites by solvent casting techniques., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The transformation of 2H-MoS 2 from semiconducting 2H to metallic 1T phases is critical for its electrochemical and device applications, where the formation and dynamics of electronic heterostructures play a key role. Using first-principles calculations, we explore detailed atomic structures and migration processes of such interfaces. While armchair interfacial bonding is severely weakened by the distortion in 1T phase, stable structures form for either Mo- or S-orientated zigzag interfaces with low contact resistance. Different zigzag interfaces have distinct local bonding, which renders interface migration behaviors strongly anisotropic. For Mo-oriented interfaces, both a low formation energy and the migration barrier of the kinks make them prone to fast migration. In contrast, the S-oriented interfaces are more immobile due to the high formation energies of kinks and thus dominate the physical properties of the whole heterostructures. Our findings not only explain various experimental observations but also provide insights into phase transition behaviors in 2D MoS 2 .

An accelerated stress test (AST) method was developed to estimate the lifetime of ion-exchange membranes in a vanadium redox flow battery. The oxidative VO 2 ions present in the charged positive electrolyte are the predominant stressor causing loss of functional groups and membrane conductivity. Membrane aging was accelerated in ex situ tests by exploiting elevated temperatures and the increased oxidative strength of Ce + ions present in the charged positive electrolyte are the predominant stressor causing loss of functional groups and membrane conductivity. Membrane aging was accelerated in ex situ tests by exploiting elevated temperatures and the increased oxidative strength of Ce 4+ . Acceleration factors were determined on the basis of the analysis of aged radiation grafted g(S-AN) membranes. The degradation in a Ce 4+ solution was found to be ∼4 times faster than in VO 2 + and Ce 4+ solutions, suggesting a similar reaction pathway. The applicability of the test was further evaluated with the second membrane, g(AMS-MAN). Its lifetime was estimated based on the accelerated stress test and acceleration factors previously determined for the g(S-AN) membrane and compared to the lifetime projected from an extended cycling experiment in the cell. The two values were in the same range of ∼4000 h. The proposed AST can serve as a basis for predictive modeling of membrane lifetime in vanadium redox flow batteries. The potential of the method and the limitations are discussed.2 + and Ce 4+ solutions, suggesting a similar reaction pathway. The applicability of the test was further evaluated with the second membrane, g(AMS-MAN). Its lifetime was estimated based on the accelerated stress test and acceleration factors previously determined for the g(S-AN) membrane and compared to the lifetime projected from an extended cycling experiment in the cell. The two values were in the same range of ∼4000 h. The proposed AST can serve as a basis for predictive modeling of membrane lifetime in vanadium redox flow batteries. The potential of the method and the limitations are discussed.

In this work, sunflower oil cake (SOC) was identified as bio-sourced material for cellulose nanocrystals (CNC) production using chemical treatments followed by sulfuric acid hydrolysis. The hydrolysis was performed at 64% acid concentration, a temperature of 50 °C and at two different hydrolysis times, 15 min (CNC 15 ) and 30 min (CNC 30 ). It was found that CNC exhibited a diameter of 9 ± 3 nm and 5 ± 2 nm, a length of 354 ± 101 nm and 329 ± 98 nm, a crystallinity of 75% and 87%, a surface charge density of ~1.57 and ~1.88 sulfate groups per 100 anhydroglucose units and a zeta potential value of -25.6 and -30.7 mV, for CNC 15 and CNC 30 , respectively. The thermal degradation under nitrogen atmosphere started at 225 °C (CNC 15 ), which is relatively higher than the temperature for sulfuric acid hydrolyzed CNC from other sources. Due to a high importance of CNC application in aqueous systems, the rheological behaviour of CNC suspensions at various concentrations was evaluated by the steady shear viscosity measurements and the oscillatory dynamic tests. The results showed that the CNC suspensions exhibited a gel-like behaviour at very low CNC concentrations (0.1-1%) wherein a strong CNC entangled network is formed. Polymer nanoreinforcing capability of the newly produced CNC was also investigated in this study. CNC filled PVA nanocomposite films were produced at various CNC contents (1, 3, 5 and 8 wt%) and their mechanical and transparency properties were investigated, resulting in transparent nanocomposite materials with strong mechanical properties. The study suggested other possibilities to utilize agricultural wastes from SOC for CNC production with potential application as reinforcement in polymer nanocomposites., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Migration of dislocations not only determines the durability of large-scale nanoelectronic and opto-electronic devices based on polycrystalline 2D transition-metal dichalcogenides (TMDCs), but also plays an important role in enhancing the performance of novel memristors. However, a fundamental question of the migration dependence on the electronic effects, which are inevitable in practical field-effect transistors based on 2D TMDCs, and its interplay with different dislocations, remains unexplored. Here, taking WS 2 as an example, first-principle calculations are used to show that the electronic contributions arising from defect states can greatly influence the migration barriers of dislocations. The barrier height can be reduced by as much as 50%, which is mainly attributed to the change in electronic occupation and the band energy of defect levels controlled by electronic chemical potential (Fermi level). The reduced barriers in turn lead to significantly enhanced migration, and thus the plasticity. Since defect levels from dislocations locate deep inside the bandgap, the doping-induced tuning of barrier height can be achieved at relatively low doping concentration through either chemical doping or electrode gating. The effective electromechanical coupling in 2D TMDCs can provide new opportunities in material engineering for various potential applications., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The present research highlights the use of a montmorillonite clay to remove p-nitrophenol (PNP) from aqueous solution. The montmorillonite clay was characterized using powder X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, X-ray fluorescence, Brunauer-Emmett-Teller analyses, and zero point charge in order to establish the adsorption behavior-properties relationship. The physiochemical parameters like pH, initial PNP concentration, and adsorbent dose as well as their binary interaction effects on the PNP adsorption yield were statistically optimized using response surface methodology. As a result, 99.5% removal of PNP was obtained under the optimal conditions of pH 2, adsorbent dose of 2 g/l, and PNP concentration of 20 mg/l. The interaction between adsorbent dose and initial concentration was the most influencing interaction on the PNP removal efficiency. The mass transfer of PNP at the solution/adsorbent interface was described using pseudo-first-order and intraparticle diffusion. Langmuir isotherm well fitted the experimental equilibrium data with a satisfactory maximum adsorption capacity of 122.09 mg/g. The PNP adsorption process was thermodynamically spontaneous and endothermic. The regeneration study showed that the montmorillonite clay exhibited an excellent recycling capability. Overall, the montmorillonite clay is very attractive as an efficient, low-cost, eco-friendly, and recyclable adsorbent for the remediation of hazardous phenolic compounds in industrial effluents.

It is essential to precisely develop low-cost and sustainable electrocatalysts for the hydrogen evolution reaction. Herein, we explore a robust and controllable hydrothermal approach to synthesize defect-rich MoS 2 nanoflakes on exfoliated MoS 2 and WS 2 . Such well-designed hetero-structural hybrids of MoS 2 /exfoliated MoS 2 and MoS 2 /exfoliated WS 2 exhibit dramatically promoted electrochemical activity and high stability. The as-grown MoS 2 nanoflakes hybridized on exfoliated MoS 2 and WS 2 generate abundant active edge sites (rich in basal defects) and unsaturated sulfur atoms, resulting in highly enhanced electrocatalytic performance. This is expected to pave the way towards a significant improvement in transition metal dichalcogenide heterostructures as electrocatalysts., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Effective sensitization of triplet states is essential to many applications, including triplet-triplet annihilation based photon upconversion schemes. This work demonstrates successful triplet sensitization of a CdSe quantum dot (QD)-bound oligothiophene carboxylic acid (T6). Transient absorption spectroscopy provides direct evidence of Dexter-type triplet energy transfer from the QD to the acceptor without populating the singlet excited state or charge transfer intermediates. Analysis of T6 concentration dependent triplet formation kinetics shows that the intrinsic triplet energy transfer rate in 1 : 1 QD-T6 complexes is 0.077 ns -1 and the apparent transfer rate and efficiency can be improved by increasing the acceptor binding strength. This work demonstrates a new class of triplet acceptor molecules for QD-based upconversion systems that are more stable and tunable than the extensively studied polyacenes.

The functionalization of nanomaterials has long been studied as a way to manipulate and tailor their properties to a desired application. Of the various methods available, the Billups-Birch reduction has become an important and widely used reaction for the functionalization of carbon nanotubes (CNTs) and, more recently, boron nitride nanotubes. However, an easily overlooked source of error when using highly reductive conditions is the utilization of poly(tetrafluoroethylene) (PTFE) stir bars. In this work, we studied the effects of using this kind of stir bar versus using a glass stir bar by measuring the resulting degree of functionalization with 1-bromododecane. Thermogravimetric analysis studies alone could deceive one into thinking that reactions stirred with PTFE stir bars are highly functionalized; however, the utilization of spectroscopic techniques, such as Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, tells otherwise. Furthermore, in the case of CNTs, we determined that using Raman spectroscopy alone for analysis is not sufficient to demonstrate successful chemical modification., Competing Interests: The authors declare no competing financial interest.

Single photon emission (SPE) by a solid-state source requires presence of a distinct two-level quantum system, usually provided by point defects. Here we note that a number of qualities offered by novel, two-dimensional materials, their all-surface openness and optical transparence, tighter quantum confinement, and reduced charge screening-are advantageous for achieving an ideal SPE. On the basis of first-principles calculations and point-group symmetry analysis, a strategy is proposed to design paramagnetic defect complex with reduced symmetry, meeting all the requirements for SPE: its electronic states are well isolated from the host material bands, belong to a majority spin eigenstate, and can be controllably excited by polarized light. The defect complex is thermodynamically stable and appears feasible for experimental realization to serve as an SPE-source, essential for quantum computing, with Re Mo V S in MoS 2 as one of the most practical candidates.

Li-ion battery commercialized by Sony in 1991 has the highest energy-density among practical rechargeable batteries and is widely used in electronic devices, electric vehicles, and stationary energy storage system in the world. Moreover, the battery market is rapidly growing in the world and further fast-growing is expected. With expansion of the demand and applications, price of lithium and cobalt resources is increasing. We are, therefore, motivated to study Na- and K-ion batteries for stationary energy storage system because of much abundant Na and K resources and the wide distribution in the world. In this account, we review developments of Na- and K-ion batteries with mainly introducing our previous and present researches in comparison to that of Li-ion battery., (© 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cocoa bean shells (CBS) are a by-product of the cocoa bean processing industry. They represent 12-20 wt% of dry cocoa beans, after having been separated from these by a roasting process. CBS often end up as a waste product which contains around 34 wt% of cellulose. The transformation of this waste into valuable and marketable products would help to improve waste disposal. Indeed, the large annual production of this waste makes it a sustainable and renewable bio-source for the production of chemicals and fibers for advanced applications. In this work, new cellulose microfibrils (CMFs) with a tendril helical morphology and highly hydrated gel-like behavior were successfully extracted from CBS waste using a controlled chemical extraction process. During this study, several physico-chemical characterizations were carried out in order to identify the properties of each of the products at different stages of treatment. Microscopic observations show that the extracted CMFs have a tendril helical shape like climbing plant tendrils. Due to this special morphology, the extracted CMFs show a highly hydrated state forming a gel network without additional modifications. The as-extracted CMFs were used as adsorbent material for the removal of methylene blue from concentrated aqueous solution, as an application to wastewater treatment for the removal of basic dyes. Swelling properties, adsorption kinetics and isotherms were carried out in batch experiments. The results indicated that the CMFs have a high swelling capacity (190%). The pseudo second order model can be effectively used to evaluate the adsorption kinetics and the adsorption isotherms can also be described well by the Langmuir isotherm model with a maximum adsorption capacity of 381.68 mg g -1 . Thus, the as-extracted CMFs with unique characteristics have the potential to be used as efficient adsorbent material for the removal of different cationic dyes from industrial wastewater., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Despite recent increased research interest in hetero-atom (B and/or N) doping effects on the oxygen reduction reaction (ORR) performance of carbon nanomaterials, microscopic understanding of active catalytic sites and effects of B and/or N doping has not been conclusively reached. Here, through comparative first-principles simulations between BN codoping and isolated B or N doping in both graphene nanoribbons (GNRs) and carbon nanotubes (CNTs), we not only identify active sites in these doped carbon nanomaterials, but elucidate the underlying mechanism of ORR processes. While the distortion of C-C bonds in CNTs leads to strong binding of O 2 , spin density distribution along the edges plays a key role in enhancing the adsorption strength of O 2 on GNRs. The effective adsorption of O 2 facilitates the following elementary reduction reactions. Based on thermodynamic analyses, O 2 adsorption as well as the electron and proton transfer to O atom are identified as key rate-determining steps. For CNTs, a good linear scaling is found between the adsorption energies of key intermediate products and that of atomic O, and thus the latter serves as a good descriptor for ORR activities. Further, N-doped high-quality CNTs are shown to exhibit best performance. For GNRs, due to edge effects, the linear relationship is broken, which promotes the catalytic activities in the BN codoping case. These findings resolve the long-standing controversy on the synergetic effects of B and N codoping, which deepens our understanding of the reaction mechanism. This work might further facilitate the optimization of the doping strategies for high-efficiency carbon-based ORR catalysts.

Black phosphorene (BP)/carbon nanotube (CNT) heterostructures can be classified as either type I or II, depending on the size of the CNTs. An external electric field (E ext ) can modulate the interfacial electronic structures and separate the electron and hole carriers of the BP/CNT heterostructures. The giant Stark effect is observed, and the band gap of the semiconducting heterostructures can vary several-fold. The intercalation of 3d transition metals can strongly bond BP and CNTs together. Furthermore, strong ferromagnetism with Curie temperature (T C ) above room temperature is predicted. It is expected that these BP/CNT heterostructures will provide new opportunities and applications in the fields of optoelectronics and electronics as well as spintronics.

The aim of the present work is to develop processes for the production of bio-oil and bio-char from algae waste using the pyrolysis at controlled conditions. The pyrolysis was carried out at different temperatures 400-600°C and different heating rates 5-50°C/min. The algal waste, bio-oil and bio-char were successfully characterized using Elemental analysis, Chemical composition, TGA, FTIR, 1 H NMR, GC-MS and SEM. At a temperature of 500°C and a heating rate of 10°C/min, the maximum yield of bio-oil and bio-char was found to be 24.10 and 44.01wt%, respectively, which was found to be strongly influenced by the temperature variation, and weakly affected by the heating rate variation. Results show that the bio-oil cannot be used as bio-fuel, but can be used as a source of value-added chemicals. On the other hand, the bio-char is a promising candidate for solid fuel applications and for the production of carbon materials., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We study the effect of hindered aggregation on the island formation process in a one- (1D) and two-dimensional (2D) point-island model for epitaxial growth with arbitrary critical nucleus size i. In our model, the attachment of monomers to preexisting islands is hindered by an additional attachment barrier, characterized by length l_{a}. For l_{a}=0 the islands behave as perfect sinks while for l_{a}→∞ they behave as reflecting boundaries. For intermediate values of l_{a}, the system exhibits a crossover between two different kinds of processes, diffusion-limited aggregation and attachment-limited aggregation. We calculate the growth exponents of the density of islands and monomers for the low coverage and aggregation regimes. The capture-zone (CZ) distributions are also calculated for different values of i and l_{a}. In order to obtain a good spatial description of the nucleation process, we propose a fragmentation model, which is based on an approximate description of nucleation inside of the gaps for 1D and the CZs for 2D. In both cases, the nucleation is described by using two different physically rooted probabilities, which are related with the microscopic parameters of the model (i and l_{a}). We test our analytical model with extensive numerical simulations and previously established results. The proposed model describes excellently the statistical behavior of the system for arbitrary values of l_{a} and i=1, 2, and 3.

The most recent and innovative silicon carbide (SiC) fiber ceramic matrix composites, used for lightweight high-heat engine parts in aerospace applications, are woven, layered, and then surrounded by a SiC ceramic matrix composite (CMC). To further improve both the mechanical properties and thermal and oxidative resistance abilities of this material, SiC nanotubes and nanowires (SiCNT/NWs) are grown on the surface of the SiC fiber via carbon nanotube conversion. This conversion utilizes the shape memory synthesis (SMS) method, starting with carbon nanotube (CNT) growth on the SiC fiber surface, to capitalize on the ease of dense surface morphology optimization and the ability to effectively engineer the CNT-SiC fiber interface to create a secure nanotube-fiber attachment. Then, by converting the CNTs to SiCNT/NWs, the relative morphology, advantageous mechanical properties, and secure connection of the initial CNT-SiC fiber architecture are retained, with the addition of high temperature and oxidation resistance. The resultant SiCNT/NW-SiC fiber can be used inside the SiC ceramic matrix composite for a high-heat turbo engine part with longer fatigue life and higher temperature resistance. The differing sides of the woven SiCNT/NWs act as the "hook and loop" mechanism of Velcro but in much smaller scale.

Intrinsic semimetallicity of graphene and silicene largely limits their applications in functional devices. Mixing carbon and silicon atoms to form two-dimensional (2D) silicon carbide (SixC1-x) sheets is promising to overcome this issue. Using first-principles calculations combined with the cluster expansion method, we perform a comprehensive study on the thermodynamic stability and electronic properties of 2D SixC1-x monolayers with 0 ≤ x ≤ 1. Upon varying the silicon concentration, the 2D SixC1-x presents two distinct structural phases, a homogeneous phase with well dispersed Si (or C) atoms and an in-plane hybrid phase rich in SiC domains. While the in-plane hybrid structure shows uniform semiconducting properties with widely tunable band gap from 0 to 2.87 eV due to quantum confinement effect imposed by the SiC domains, the homogeneous structures can be semiconducting or remain semimetallic depending on a superlattice vector which dictates whether the sublattice symmetry is topologically broken. Moreover, we reveal a universal rule for describing the electronic properties of the homogeneous SixC1-x structures. These findings suggest that the 2D SixC1-x monolayers may present a new "family" of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.

Two-dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure-search method, both based on first-principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B12 is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate-dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Harnessing the energy from hot charge carriers is an emerging research area with the potential to improve energy conversion technologies.1-3 Here we present a novel plasmonic photoelectrode architecture carefully designed to drive photocatalytic reactions by efficient, nonradiative plasmon decay into hot carriers. In contrast to past work, our architecture does not utilize a Schottky junction, the commonly used building block to collect hot carriers. Instead, we observed large photocurrents from a Schottky-free junction due to direct hot electron injection from plasmonic gold nanoparticles into the reactant species upon plasmon decay. The key ingredients of our approach are (i) an architecture for increased light absorption inspired by optical impedance matching concepts,4 (ii) carrier separation by a selective transport layer, and (iii) efficient hot-carrier generation and injection from small plasmonic Au nanoparticles to adsorbed water molecules. We also investigated the quantum efficiency of hot electron injection for different particle diameters to elucidate potential quantum effects while keeping the plasmon resonance frequency unchanged. Interestingly, our studies did not reveal differences in the hot-electron generation and injection efficiencies for the investigated particle dimensions and plasmon resonances.

The two-dimensional (2D) transition metal dichalcogenides (TMDC, of generic formula MX2) monolayer displays the "triple-decker" structure with the chemical bond organization much more complex than in well-studied monatomic layers of graphene or boron nitride. Accordingly, the makeup of the dislocations in TMDC permits chemical variability, depending sensitively on the equilibrium with the environment. In particular, first-principles calculations show that dislocations state can be switched to highly mobile, profoundly changing the lattice relaxation and leading to superplastic behavior. With 2D MoS2 as an example, we construct full map for dislocation dynamics, at different chemical potentials, for both the M- and X-oriented dislocations. Depending on the structure of the migrating dislocation, two different dynamic mechanisms are revealed: either the direct rebonding (RB) mechanism where only a single metal atom shifts slightly, or generalized Stone-Wales (SW(g)) rotation in which several atoms undergo significant displacements. The migration barriers for RB mechanism can be 2-4 times lower than for the SW(g). Our analyses show that within a range of chemical potentials, highly mobile dislocations could at the same time be thermodynamically favored, that is statistically dominating the overall material property. This demonstrates remarkable possibility of changing material basic property such as plasticity by changing elemental chemical potentials of the environment.

CONSPECTUS: While some exceptional properties are unique to graphene only (its signature Dirac-cone gapless dispersion, carrier mobility, record strength), other features are common to other two-dimensional materials. The broader family "beyond graphene" offers greater choices to be explored and tailored for various applications. Transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), and 2D layers of pure elements, like phosphorus or boron, can complement or even surpass graphene in many ways and uses, ranging from electronics and optoelectronics to catalysis and energy storage. Their availability greatly relies on chemical vapor deposition growth of large samples, which are highly polycrystalline and include interfaces such as edges, heterostructures, and grain boundaries, as well as dislocations and point defects. These imperfections do not always degrade the material properties, but they often bring new physics and even useful functionality. It turns particularly interesting in combination with the sheer openness of all 2D sheets, fully exposed to the environment, which, as we show herein, can change and tune the defect structures and consequently all their qualities, from electronic levels, conductivity, magnetism, and optics to structural mobility of dislocations and catalytic activities. In this Account, we review our progress in understanding of various defects. We begin by expressing the energy of an arbitrary graphene edge analytically, so that the environment is regarded by "chemical phase shift". This has profound implications for graphene and carbon nanotube growth. Generalization of this equation to heteroelemental BN gives a method to determine the energy for arbitrary edges of BN, depending on the partial chemical potentials. This facilitates the tuning of the morphology and electronic and magnetic properties of pure BN or hybrid BN|C systems. Applying a similar method to three-atomic-layer TMDCs reveals more diverse edge structures for thermodynamically stable flakes. Moreover, CVD samples show new types of edge reconstruction, providing insight into the nonequilibrium growth process. Combining dislocation theory with first-principles computations, we could predict the dislocation cores for BN and TMDC and reveal their variable chemical makeup. This lays the foundation for the unique sensitivity to ambient conditions. For example, partial occupation of the defect states for dislocations in TMDCs renders them intrinsically magnetic. The exchange coupling between electrons from neighboring dislocations in grain boundaries further makes them half-metallic, which may find its applications in spintronics. Finally, brief discussion of monoelemental 2D-layer phosphorus and especially the structures and growth routes of 2D boron shows how theoretical assessment can help the quest for new synthetic routes.

The deep gap states created by defects in semiconductors typically deteriorate the performance of (opto)electronic devices. This has limited the applications of two-dimensional (2D) metal dichalcogenides (MX2) and underscored the need for a new 2D semiconductor without defect-induced deep gap states. In this work, we demonstrate that a 2D mono-elemental semiconductor is a promising candidate. This is exemplified by first-principles study of 2D phosphorus (P), a recently fabricated high-mobility semiconductor. Most of the defects, including intrinsic point defects and grain boundaries, are electronically inactive, thanks to the homoelemental bonding, which is not preferred in heteroelemental system such as MX2. Unlike MX2, the edges of which create deep gap states and cannot be eliminated by passivation, the edge states of 2D P can be removed from the band gap by hydrogen termination. We further find that both the type and the concentration of charge carriers in 2D P can be tuned by doping with foreign atoms. Our work sheds light on the role of defects in the electronic structure of materials.

Carbon nanotubes hold enormous technological promise. It can only be harnessed if one controls their chirality, the feature of the tubular carbon topology that governs all the properties of nanotubes-electronic, optical, mechanical. Experiments in catalytic growth over the last decade have repeatedly revealed a puzzling strong preference towards minimally chiral (near-armchair) tubes, challenging any existing hypotheses and making chirality control ever more tantalizing, yet leaving its understanding elusive. Here we combine the nanotube/catalyst interface thermodynamics with the kinetic growth theory to show that the unusual near-armchair peaks emerge from the two antagonistic trends at the interface: energetic preference towards achiral versus the faster growth kinetics of chiral nanotubes. This narrow distribution is inherently related to the peaked behaviour of a simple function, xe(-x).

First-principles calculations for carbyne under strain predict that the Peierls transition from symmetric cumulene to broken-symmetry polyyne structure is enhanced as the material is stretched. Interpretation within a simple and instructive analytical model suggests that this behavior is valid for arbitrary 1D metals. Further, numerical calculations of the anharmonic quantum vibrational structure of carbyne show that zero-point atomic vibrations eliminate the Peierls distortion in the mechanically free chain, preserving the cumulene symmetry. The emergence and increase of Peierls dimerization under tension then implies a qualitative transition between the two forms, which our computations place around 3% strain. Thus, the competition between the zero-point vibrations and mechanical strain determines a switch in symmetry resulting in the transition from metallic state to a dielectric, with a small effective mass and a high carrier mobility. In any practical realization, it is important that the effect is also chemically modulated by the choice of terminating groups. These findings are promising for applications such as electromechanical switching and band gap tuning via strain, and besides carbyne itself, they directly extend to numerous other systems that show Peierls distortion.

Many key performance characteristics of carbon-based lithium-ion battery anodes are largely determined by the strength of binding between lithium (Li) and sp(2) carbon (C), which can vary significantly with subtle changes in substrate structure, chemistry, and morphology. Here, we use density functional theory calculations to investigate the interactions of Li with a wide variety of sp(2) C substrates, including pristine, defective, and strained graphene, planar C clusters, nanotubes, C edges, and multilayer stacks. In almost all cases, we find a universal linear relation between the Li-C binding energy and the work required to fill previously unoccupied electronic states within the substrate. This suggests that Li capacity is predominantly determined by two key factors-namely, intrinsic quantum capacitance limitations and the absolute placement of the Fermi level. This simple descriptor allows for straightforward prediction of the Li-C binding energy and related battery characteristics in candidate C materials based solely on the substrate electronic structure. It further suggests specific guidelines for designing more effective C-based anodes. The method should be broadly applicable to charge-transfer adsorption on planar substrates, and provides a phenomenological connection to established principles in supercapacitor and catalyst design.

We study the Li clustering process on graphene and obtain the geometry, nucleation barrier, and electronic structure of the clusters using first-principles calculations. We estimate the concentration-dependent nucleation barrier for Li on graphene. While the nucleation occurs more readily with increasing Li concentration, possibly leading to the dendrite formation and failure of the Li-ion battery, the existence of the barrier delays nucleation and may allow Li storage on graphene. Our electronic structure and charge transfer analyses reveal how the fully ionized Li adatoms transform to metallic Li during the cluster growth on graphene.