Gas Sensors Based on Chemi?Resistive Hybrid Functional Nanomaterials

Chemi-resistive sensors based on hybrid functional materials are promising candidates for gas sensing with high responsivity,good selectivity,fast response/recovery,great stability/repeatability,room-working temperature,low cost,and easy-to-fabricate,for versatile applications.This progress report reviews the advantages and advances of these sensing structures compared with the single constituent,according to five main sensing forms:manipulating/constructing heterojunctions,catalytic reaction,charge transfer,charge carrier transport,molecular binding/sieving,and their combinations.Promises and challenges of the advances of each form are presented and discussed.Critical thinking and ideas regarding the orientation of the development of hybrid material-based gas sensor in the future are discussed.     

Multiscale Soft–Hard Interface Design for Flexible Hybrid Electronics

Emerging next-generation soft electronics will require versatile properties functioning under mechanical compliance, which will involve the use of different types of materials. As a result, control over material interfaces (particularly soft/hard interfaces) has become crucial and is now attracting intensive worldwide research efforts. A series of material and structural interface designs has been devised to improve interfacial adhesion, preventing failure of electromechanical properties under mechanical deformation. Herein, different soft/hard interface design strategies at multiple length scales in the context of flexible hybrid electronics are reviewed. The crucial role of soft ligands and/or polymers in controlling the morphologies of active nanomaterials and stabilizing them is discussed, with a focus on understanding the soft/hard interface at the atomic/molecular scale. Larger nanoscopic and microscopic levels are also discussed, to scrutinize viable intrinsic and extrinsic interfacial designs with the purpose of promoting adhesion, stretchability, and durability. Furthermore, the macroscopic device/human interface as it relates to real-world applications is analyzed. Finally, a perspective on the current challenges and future opportunities in the development of truly seamlessly integrated soft wearable electronic systems is presented.     

Rational Design of Soft–Hard Interfaces through Bioinspired Engineering

Soft–hard tissue interfaces in nature present a diversity of hierarchical transitions in composition and structure to address the challenge of stress concentrations that would otherwise arise at their interface. The translation of these into engineered materials holds promise for improved function of biomedical interfaces. Here, soft–hard tissue interfaces found in the body in health and disease, and the application of the diverse, functionally graded, and hierarchical structures that they present to bioinspired engineering materials are reviewed. A range of such bioinspired engineering materials and associated manufacturing technologies that are on the horizon in interfacial tissue engineering, hydrogel bioadhesion at the interfaces, and healthcare and medical devices are described.     

Rational Design of a High-Loading Polysulfide Cathode and a Thin-Lithium Anode for Developing Lean-Electrolyte Lithium–Sulfur Full Cells

Lithium-sulfur cells are attractive energy-storage systems because of their high energy density and the electrochemical utilization rates of the high-capacity lithium-metal anode and the low-cost sulfur cathode. The commercialization of high-performance lithium–sulfur cells with high discharge capacity and cyclic stability requires the optimization of practical cell-design parameters. Herein, a carbon structural material composed of a carbon nanotube skeleton entrapping conductive graphene is synthesized as an electrode substrate. The carbon structural material is optimized to develop a high-loading polysulfide cathode with a high sulfur loading capacity (6–12 mg cm⁻²), rate performance (C/10–C/2), and cyclic stability for 200 cycles. A thin lithium anode based on the carbon structural material is developed and exhibits long lithium stripping/plating stability for ≈2500 h with a lithium-ion transference number of 0.68. A lean-electrolyte lithium–sulfur full cell with a low electrolyte-to-sulfur ratio of 6 µL mg⁻¹ is constructed with the designed high-loading polysulfide cathode and the thin lithium anode. The integration of all the critical cell-design parameters endows the lithium–sulfur full cell with a low negative-to-positive capacity ratio of 2.4, while exhibiting stable cyclability with an initial discharge capacity of 550 mAh g⁻¹ and 60% capacity retention after 200 cycles.     

Design of Hybrid Composites with Zero Coefficient of Thermal Expansion

Structures used in aerospace are influenced by temperature. So coefficient of thermal expansion (CTE) is not only an important parameter of materials, but also a significant parameter of structural design of spacecrafts with high dimensional stability. In this paper, based on the analysis of the data from tests, theoretical formulae for predicting CTE and mechanical properties of hybrid composites are presented, and the calculation program is compiled. All the equations are verified by experiments. Optimization is conducted by computer. The results and methods presented in this paper can be used both in optimal design of hybrid composites with zero CTE and in design of hybrid composites with any certain CTE value     

Molecular Dynamics Simulation of Pervaporation of an Ethanol–Water Mixture on a Hybrid Silicon Oxide Membrane

A molecular-statistical method for simulating the process of pervaporation on hybrid silicon oxide membranes is proposed. This method is a development of the control volume method. Models of three membrane samples with different densities and pore sizes were obtained. These samples were used for the molecular-dynamics simulation of pervaporation of a 95 mol % aqueous solution of ethanol at a temperature of 343 K. It is shown that the membrane is selective with respect to water; the component flow is found to exponentially depend on the pore size.     

Hybrid FE–IDQ–CG method for dynamic parameters estimation of multilayered half-space

As a first endeavor, a hybrid finite element (FE)–incremental differential quadrature (IDQ) method together with the discrepancy principle and the conjugate gradient method (CGM) is used to develop an inverse algorithm for the parameters estimation of the axisymmetric multilayered half-spaces. The approach is based on the measurement of the dynamic transverse displacement at some boundary points of the half-space to estimate the unknown parameters of its layers. Using the accuracy and unconditional stability of the hybrid FE–IDQ method, the direct problem is solved to get the dynamic transverse displacements. After adding some random errors to the obtained results, they are considered as the measured responses by sensors. Then, the conjugate gradient method as a general and robustness optimization technique is employed to minimize the error between the measured and calculated dynamic surface responses at sensor locations. The sensitivity analysis of the displacement field is performed using a semi-analytical method. The applicability and correctness of the proposed hybrid algorithm is demonstrated through different examples by considering the influence of the layers arrangement, the measurement errors and sensor numbers.     

A Rational Reconfiguration of Electrolyte for High-Energy and Long-Life Lithium–Chalcogen Batteries

Lithium–chalcogen batteries are an appealing choice for high-energy-storage technology. However, the traditional battery that employs liquid electrolytes suffers irreversible loss and shuttle of the soluble intermediates. New batteries that adopt Li⁺-conductive polymer electrolytes to mitigate the shuttle problem are hindered by incomplete discharge of sulfur/selenium. To address the trade-off between energy and cycle life, a new electrolyte is proposed that reconciles the merits of liquid and polymer electrolytes while resolving each of their inferiorities. An in situ interfacial polymerization strategy is developed to create a liquid/polymer hybrid electrolyte between a LiPF₆-coated separator and the cathode. A polymer-gel electrolyte in situ formed on the separator shows high Li⁺ transfer number to serve as a chemical barrier against the shuttle effect. Between the gel electrolyte and the cathode surface is a thin gradient solidification layer that enables transformation from gel to liquid so that the liquid electrolyte is maintained inside the cathode for rapid Li⁺ transport and high utilization of active materials. By addressing the dilemma between the shuttle chemistry and incomplete discharge of S/Se, the new electrolyte configuration demonstrates its feasibility to trigger higher capacity retention of the cathodes. As a result, Li–S and Li–Se cells with high energy and long cycle lives are realized, showing promise for practical use.     

Simple Construction of Multistage Stable Silicon–Graphite Hybrid Granules for Lithium-Ion Batteries

Because of its high specific capacity, the silicon–graphite composite (SGC) is regarded as a promising anode for new-generation lithium-ion batteries. However, the frequently employed two-section preparation process, including the modification of silicon seed and followed mixture with graphite, cannot ensure the uniform dispersion of silicon in the graphite matrix, resulting in a stress concentration of aggregated silicon domains and cracks in composite electrodes during cycling. Herein, inspired by powder engineering, the two independent sections are integrated to construct multistage stable silicon–graphite hybrid granules (SGHGs) through wet granulation and carbonization. This method assembles silicon nanoparticles (Si NPs) and graphite and improves compatibility between them, addressing the issue of severe stress concentration caused by uncombined residue of Si NPs. The optimal SGHG prepared with 20% pitch content exhibits a highly reversible specific capacity of 560.0 mAh g⁻¹ at a current density of 200 mA g⁻¹ and a considerable stability retention of 86.1% after 1000 cycles at 1 A g⁻¹. Moreover, as a practical application, the full cell delivers an outstanding capacity retention of 85.7% after 400 cycles at 2 C. The multistage stable structure constructed by simple wet granulation and carbonization provides theoretical guidance for the preparation of commercial SGC anodes.     

Graphene–Gold Nano-ring antenna for Dual-resonance optical application

To achieve dual resonance qualification, we are suggested a sub-wavelength dual-ring Nano-antenna based on combination of Graphene and gold where Nano-Antenna with dual-resonance is attractive for spectroscopy and bio-sensing applications. The result shows that with these structures, we could be achieved dual-resonance characteristic of Infra red (IR) and optical regime. In addition, by biasing of the Graphene, we are attained a reconfigurable characteristic for our second resonance. Therefore, in this current research, the extinction, reflection and absorption cross section are studied for every structure and formation. For modeling the prototype Nano-antenna, SiN Substrate is selected with refractive index of 1.98 and silver with Palik optical characteristic for metal layer is modified. Simulation has been done with FDTD method. Of course, because of symmetry of the structure, the prototype Nano-antenna has similar manner for vertical or horizontal polarization. As a result, proposed Nano-antenna is useful for THz medical spectroscopy with simple method of designing and second frequency controlling only with graphene biasing. Here, we are debated about graphene placement and biasing interaction on the bonding and anti-bonding mode where we show that the gold and graphene interaction will affect on E-field distribution by making dipole or quad resonance.     

Ultrathin 2D Metal–Organic Framework Nanosheets In situ Interpenetrated by Functional CNTs for Hybrid Energy Storage Device

The controllable construction of two-dimensional(2D)metal–organic framework(MOF)nanosheets with favorable electrochemical performances is greatly challenging for energy storage.Here,we design an in situ induced growth strategy to construct the ultrathin carboxylated carbon nanotubes(C-CNTs)interpenetrated nickel MOF(Ni-MOF/C-CNTs)nanosheets.The deliberate thickness and specific surface area of novel 2D hybrid nanosheets can be effectively tuned via finely controlling C-CNTs involvement.Due to the unique microstructure,the integrated 2D hybrid nanosheets are endowed with plentiful electroactive sites to promote the electrochemical performances greatly.The prepared Ni-MOF/C-CNTs nanosheets exhibit superior specific capacity of 680 C g^−1 at 1 A g^−1 and good capacity retention.The assembled hybrid device demonstrated the maximum energy density of 44.4 Wh kg^−1 at a power density of 440 W kg^−1.Our novel strategy to construct ultrathin 2D MOF with unique properties can be extended to synthesize various MOF-based functional materials for diverse applications.     

Hybrid titanium–CFRP laminates for high-performance bolted joints

This paper presents an experimental and numerical investigation of the mechanical response of bolted joints manufactured using new hybrid composite laminates based on the substitution of CFRP plies with titanium plies. The local hybridization of the material is proposed to increase the efficiency of the bolted joints in CFRP structures. Two modeling strategies, based on non-linear finite element methods, are proposed for the analysis of the bolt-bearing and transition regions of the hybrid laminates. The bolt-bearing region is simulated using a three-dimensional finite element model that predicts ply failure mechanisms, whereas the free-edge of the transition region is simulated using plane stress and cohesive elements. The numerical and experimental results indicate that the use of hybrid composites can drastically increase the strength of CFRP bolted joints and therefore increase the efficiency of this type of connection. In addition, the numerical models proposed are able to predict the failure mechanisms and the strength of hybrid composite laminates with a good accuracy.     

Triboelectric–Electromagnetic Hybrid Generator for Harvesting Blue Energy

Nano-Micro Letters - The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to...     

Gradient-Concentration Design of Stable Core–Shell Nanostructure for Acidic Oxygen Reduction Electrocatalysis

Manipulating the surface structure of electrocatalysts at the atomic level is of primary importance to simultaneously achieve the activity and stability dual-criteria in oxygen reduction reaction (ORR) for proton exchange membrane fuel cells. Here, a durable acidic ORR electrocatalyst with the “defective-armored” structure of Pt shell and Pt–Ni core nanoparticle decorated on graphene (Pt–Ni@Pt_D/G) using a facile and controllable galvanic replacement reaction to generate gradient distribution of Pt–Ni composition from surface to interior, followed by a partial dealloying approach, leaching the minor nickel atoms on the surface to generate defective Pt skeleton shell, is reported. The Pt–Ni@Pt_D/G catalyst shows impressive performance for ORR in acidic (0.1 m HClO₄) electrolyte, with a high mass activity of threefold higher than that of Pt/C catalyst owing to the tuned electronic structure of locally concave Pt surface sites through synergetic contributions of Pt–Ni core and defective Pt shell. More importantly, the electrochemically active surface areas still retain 96% after 20 000 potential cycles, attributing to the Pt atomic shell acting as the protective “armor” to prevent interior Ni atoms from further dissolution during the long-term operation.     

Design and analysis of longitudinal–flexural hybrid transducer for ultrasonic peen forming

Ultrasonic peen forming (UPF) is an emerging technology that exhibits great superiority in both its flexible operating modes and the deep residual stress that it produces compared with conventional plastic forming methods.Although ultrasonic transducers with longitudinal vibration have been widely studied,they have seldom been incorporated into UPF devices for machining in confined spaces.To meet the requirements of this type of machining,a sandwich-type piezoelectric transducer with coupled lon...     

Hybrid organic–inorganic porous semiconductor transducer for multi-parameters sensing

Porous silicon (PSi) non-symmetric multi-layers are modified by organic molecular beam deposition of an organic semiconductor, namely the N,N′-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN₂). Joule evaporation of PDIF-CN₂ into the PSi sponge-like matrix not only improves but also adds transducing skills, making this solid-state device a dual signal sensor for chemical monitoring. PDIF-CN₂ modified PSi optical microcavities show an increase of about five orders of magnitude in electric current with respect to the same bare device. This feature can be used to sense volatile substances. PDIF-CN₂ also improves chemical resistance of PSi against alkaline and acid corrosion.     

A Molecular Dynamics Study for the Thermophysical Properties of Liquid Ti–Al Alloys

Molecular dynamics simulations (MDS) employing an embedded-atom-method (EAM) are applied to calculate the density and specific heat of liquid Ti–Al alloys at temperatures above and below the melting temperature in a wide composition range. Both the temperature and composition dependences of these two properties are investigated. The excess volume of Ti–Al alloys is calculated from the predicted density, and shows a negative value. The specific heat of liquid Ti–Al alloys increases linearly with a decrease of temperature. Unlike the monotonic change of density with the addition of aluminum, the specific heat reaches its maximum value at the composition of Ti–50at%Al alloy. Thus, both the density and specific heat show highly nonideal behaviors, indicating that Neumann–Kopp’s rule does not apply.     

Molecular Simulation of Joule–Thomson Inversion Curves

A method to determine Joule–Thomson inversion curves, using isobaric-isothermal Monte Carlo molecular simulations, is presented. The usual experimental practice to obtain the locus of points in which the isenthalpic derivative of temperature with respect to pressure vanishes is to process volumetric data by means of thermodynamic relations. This experimental procedure requires the very precise measurement of volumetric properties at conditions up to five times the fluid's critical temperature and twelve times its critical pressure. These harsh experimental conditions have hindered the publication of data for even simple fluids and mixtures. By using molecular simulation, these problems may be circumvented, since the computational effort is roughly independent of the actual value of the pressure or the temperature. In general, Joule–Thomson inversion curves obtained by molecular simulation may be used either as an unambiguous test for equations of state in the supercritical and high-pressure regions or for the prediction of real fluid behavior, should the potential be well known. Both applications are exemplified for a Lennard-Jones fluid for which the complete inversion curve is obtained.     

Tumor-Microenvironment-Triggered Ion Exchange of a Metal–Organic Framework Hybrid for Multimodal Imaging and Synergistic Therapy of Tumors

Nanotheranostic agents (NTAs) that integrate diagnostic capabilities and therapeutic functions have great potential for personalized medicine, yet poor tumor specificity severely restricts further clinical applications of NTAs. Here, a pro-NTA (precursor of nanotheranostic agent) activation strategy is reported for in situ NTA synthesis at tumor tissues to enhance the specificity of tumor therapy. This pro-NTA, also called PBAM, is composed of an MIL-100 (Fe)-coated Prussian blue (PB) analogue (K₂Mn[Fe(CN)₆]) with negligible absorption in the near-infrared region and spatial confinement of Mn²⁺ ions. In a mildly acidic tumor microenvironment (TME), PBAM can be specifically activated to synthesize the photothermal agent PB nanoparticles, with release of free Mn²⁺ ions due to the internal fast ion exchange, resulting in the “ON” state of both T₁-weighted magnetic resonance imaging and photoacoustic signals. In addition, the combined Mn²⁺-mediated chemodynamic therapy in the TME and PB-mediated photothermal therapy guarantee a more efficient therapeutic performance compared to monotherapy. In vivo data further show that the pro-NTA activation strategy could selectively brighten solid tumors and detect invisible lymph node metastases with high specificity.