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Rechargeable aqueous zinc-ion batteries (AZIBs) that directly use metallic zinc as anode and mildly acidic Zn2+-containing aqueous solutions as electrolytes have exhibited promising complementarity for well-established lithium-ion batteries. The fabrication of high-voltage, high-capacity, and durable cathode and stable anode are the burning issues of fabricating high-performance AZIBs. Herein, the small amount of dual-cation preintercalated and amorphous carbon confined vanadium dioxide (Ni0.006Ca0.0045VO2@C) was prepared for high-performance Zn2+-storage materials, and subsequent in situ electrochemical anodic oxidation strategy was used to convert Ni0.006Ca0.0045VO2@C to δ-(Ni,Ca)V2O5@C as high-capacity AZIB cathode. The elaborate architecture not only showed a high specific capacity of 433.8 mAh g−1 at 0.1 A g−1 but also retained a reversible capacity of 74 mAh g−1 after 4000 cycles at 5 A g−1. In addition, the Zn2+/H+ co-intercalation mechanism was also verified by employing ex situ XRD and ex situ XPS. Finally, the flexible quasi-solid-state ZIBs were also assembled with the Ni0.006Ca0.0045VO2@C as cathode and polyvinyl alcohol hydrogel as electrolyte, suggesting its promising application for the superior Zn2+-storage performance.

The design and preparation of electrode materials are of great significance for improving the overall performance of energy storage devices. Zeolitic imidazolate frameworks (ZIFs) and their derivatives have attracted significant attention as they provide a library of new energy storage materials. ZIFs act as the perfect precursor due to their high porosity, controllable crystal structures, and tunable chemical compositions. The high structural tunability endows ZIFs and ZIFs-derivatives with broad application prospects in various energy storage devices. In this review, we discussed the crystal structures and preparation methods of ZIFs and focused on the application progress of ZIFs and ZIFs-derivatives in supercapacitors and batteries. Furthermore, we summarized the current challenges and provided perspectives about ZIFs and their derivatives for future electrode materials, aiming to fully understand this field and promote the widespread use of ZIF-based composites and ZIF-derived materials in the field of energy storage.

Unique two-dimensional (2D) porous nanosheets with overwhelmingly rich channels and large specific surface area exhibit superior electrochemical capacitance performance, as compared to the conventional zero- and one-dimensional counterparts. As ternary transition metal sulfides (TMSs) are well recognized for their high electrochemical activity and capacity, and the replacement of oxygen with sulfur may result in high stability and flexible properties of the nanomaterials, as compared to transition metal oxides, herein we report the synthesis of 2D porous nanosheet arrays of ZnxCo1-xS (x = 0, 0.25, 0.5, 0.75, and 1) via a facile hydrothermal process. Due to the synergistic effect of the metal components and a unique 2D porous structure, the Zn0.5Co0.5S electrode was found to stand out as the best among the series, with a high specific capacity of 614 C g−1 at 1 A g−1 and excellent cycle retention rate of 90 % over 10, 000 cycles at 10 A g−1. Notably, a supercapattery based on a Zn0.5Co0.5S positive electrode and an activated carbon (AC) negative electrode (Zn0.5Co0.5S//AC) was found to display a 1.6 V voltage window, a 61 mA h g−1 specific capacity at 1 A g−1, a 49 Wh kg–1 energy density at 957 W kg–1 power density, and excellent cycling performance (88 % over 10, 000 cycles), suggesting tremendous potential of Zn0.5Co0.5S in the development of high-performance supercapattery devices.

Metal phosphates, such as LiFePO4 (LFP), have been attracting extensive attention as electrode materials for next-generation rechargeable metal-ion batteries (MIBs), due to their high theoretical capacity, good chemical stability, long lifespan, and natural abundance. In this review, the recent progress of the design and engineering of metal phosphate-based electrode materials for MIBs is summarized. Specifically, the survey will focus on three types of phosphates, monometallic phosphates, bimetallic phosphates, and multi-metal phosphates, within the context of their intrinsic structure and corresponding electrochemical performance. A range of experimental variables will be carefully analyzed, such as sample synthesis, crystal structure, and electrochemical reaction mechanism, in conjunction with theoretical calculations. The applications of these materials as MIB electrodes are then featured for diverse MIBs, such as lithium-ion battery, sodium-ion batteries, potassium-ion batteries, calcium-ion batteries, and magnesium-ion batteries. We conclude the review with a perspective where the promises and challenges of phosphate-based electrodes for MIBs are highlighted, along with future research directions.

Typical layered structures with large capacity have attracted much interest in lithium ion batteries and emerging post-lithium ion batteries. However, these typical layered oxides, including α-, δ-V2O5, δ-MnO2, and α-MoO3, have suffered poor electrical conductivity, severe structural deterioration, and sluggish diffusion kinetics during the repetitive charging/discharging process. In recent years, interlayer engineering of preintercalation strategies has offered effective solutions for solving these problems. Structural water molecules (H2O), monovalent alkali cations (Li+/Na+/K+) and ammonium ion ( NH 4 + ), multivalent alkali-earth cations (Mg2+/Ca2+/Ba2+) and aluminum ion (Al3+), various transition metal cations (Mn2+/Fe2+/Co2+/Ni2+/Cu2+/Zn2+/Ag+, etc.), and organic molecules (PANI/PEDOT/PEO, etc.) have been proved to be efficient “pillars” for stabilizing the fragile layered structure and enhanced diffusion kinetics. These prominent effects have boosted the developments of preintercalated layered structures for emerging multivalent metal-ion batteries, especially rechargeable aqueous zinc ion batteries (AZIBs). In this review, we have clarified the representative crystal structures, preparation methods, advanced characterization methods and corresponding mechanistic insights, and successful applications of these preintercalated layered oxides in multivalent metal-ion batteries.

Two-dimensional (2D) titanium (Ti)-based nanomaterials have been extensively investigated due to their small strain expansion, abundant ion diffusion paths, high safety, and low cost. Nonetheless, such Ti-based nanosheets typically exhibit only poor electrical conductivity and can easily restack. Great efforts have been contributed to alleviating these issues based on nanofabrication and nanoengineering strategies. In this review, we survey the recent progress of the preparation and applications of 2D Ti-based nanostructures in electrochemical energy storage, such as supercapacitors, lithium-ion batteries, sodium-ion batteries, and other multivalent metal-ion batteries, with a focus on the crystal structure, electrochemical energy storage mechanism, and advanced in situ characterization techniques. Finally, a perspective is included to highlight the challenges and promises in the exploitation of 2D Ti-based materials for further enhancement of the performance of energy storage devices.

Niobium (Nb)-based materials show great potential in the field of supercapacitors (SCs) and hybrid ion capacitors (HICs) because of their unique crystal structure, rapid ion diffusion ability, excellent chemical durability, and high safety, although they are rare and expensive. However, pure niobium pentoxide has poor conductivity, so the preparation of composite materials and doped materials can effectively enhance its conductivity, thus improving its rate capability. In this review, we summarize the research advances in Nb-based oxides and composites, niobium nitrides, niobium carbides, niobium selenides, and niobium sulfides in recent years. We compare the effect of crystal structures, synthesis methods, and morphology control on the electrochemical performance of niobium-based materials. The energy storage mechanism of Nb-based materials is discussed through corresponding electrochemical reactions and advanced characterization technologies. In addition, the feasible strategies to improve the electrochemical performance of Nb electrodes are briefly introduced. Finally, the future challenges and outlooks of Nb-based materials in energy storage devices are also discussed.

In this work, for the first time, we managed to derive the hierarchical porous carbon (HPC) at a large scale from the carbonization of franchet groundcherry fruit peels. With the interconnected por...

As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 $${\boldsymbol{\mu }}$$ µ m diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.

The emergence of energy crisis and greenhouse effect has prompted people to develop energy storage equipment with excellent performance. Supercapacitors (SCs), also known as electrochemical capacitors, are widely studied for their high power density, fast charge and discharge and long cycle life. Rare earth is a group of elements with unique structure and properties. Rare earth-based nanomaterials, especially rare earth oxides, hydroxides and sulfides, have attracted much attention due to their good redox properties and environmentally friendly characteristics. Rare earth-based SCs nanomaterials can be obtained by environmentally friendly, simple and low-cost methods, such as hydrothermal/solvothermal method, electrodeposition method, atomic layer deposition method, etc. This paper reviews the synthesis methods, morphology and electrochemical properties of various rare earth-based nanomaterials and their composites for SCs. Finally, based on the reported literature, we discussed some challenges faced by rare earth-based nanomaterials and the issues that need attention in SCs and other electrochemical energy storage fields in the future.

Description, A light weight, economic, and high–energy density Zn/MnO2 fiber battery was integrated with a textile body area network., Electronic textiles (e-textiles), having the capability of interacting with the human body and surroundings, are changing our everyday life in fundamental and meaningful ways. Yet, the expansion of the field of e-textiles is still limited by the lack of stable and biocompatible power sources with aesthetic designs. Here, we report a rechargeable solid-state Zn/MnO2 fiber battery with stable cyclic performance exceeding 500 hours while maintaining 98.0% capacity after more than 1000 charging/recharging cycles. The mechanism of the high electrical and mechanical performance due to the graphene oxide–embedded polyvinyl alcohol hydrogel electrolytes was rationalized by Monte Carlo simulation and finite element analysis. With a collection of key features including thin, light weight, economic, and biocompatible as well as high energy density, the Zn/MnO2 fiber battery could seamlessly be integrated into a multifunctional on-body e-textile, which provides a stable power unit for continuous and simultaneous heart rate, temperature, humidity, and altitude monitoring.

In this study, we present the observation of the giant magnetoelastic effect that occurs in soft elastomer systems without the need of external magnetic fields and possesses a magnetomechanical coupling factor that is four times larger than that of traditional rigid metal-based ferromagnetic materials. To investigate the fundamental scientific principles at play, we built a linear model by using COMSOL Multiphysics, which was consistent with the experimental observations. Next, by combining the giant magnetoelastic effect with electromagnetic induction, we developed a magnetoelastic generator (MEG) for biomechanical energy conversion. The wearable MEG demonstrates an ultrahigh output current of 97.17 mA, a low internal impedance of around ∼40 Ω, and an intrinsic waterproof property. We further leveraged the wearable MEG as an ultrahigh current power source to drive a Joule-heating textile for personalized thermoregulation, which increased the temperature of the fiber-shaped resistor by 0.2 °C. The development of the wearable MEG will act as an alternative and compelling approach for on-body electricity generation and arouse a wide range of possibilities in the renewable energy community.

Summary We discovered a giant magnetoelasticity in soft matter with up to 5-fold enhancement of magnetomechanical coupling factors compared to that of rigid metal alloys without an externally applied magnetic field. A wavy chain analytical model based on the magnetic dipole-dipole interaction and demagnetizing field was established, fitting well to the experimental observation. To explore its potentials in electronic textiles, we coupled it with magnetic induction to invent a textile magnetoelastic generator (MEG), a new working mechanism for biomechanical energy conversion, featuring an intrinsic waterproofness, an ultralow internal impedance of approximately 20 Ω, and a high short-circuit current density of 1.37 mA/cm2, which is about four orders of magnitude higher than that of other textile generator counterparts. Meanwhile, assisted by machine learning, the textile MEG could continuously monitor the respiratory activities on heavily perspiring skin without any encapsulation, allowing a timely diagnosis of the respiration abnormalities in a self-powered manner. We foresee that this discovery can be extended to wide-range soft-matter systems, emerging as a compelling approach to develop electronic textiles for energy, sensing, and therapeutic applications.

Magnetoelastic effect characterizes the change of materials’ magnetic properties under mechanical deformation, which is conventionally observed in some rigid metals or metal alloys. Here we show magnetoelastic effect can also exist in 1D soft fibers with stronger magnetomechanical coupling than that in traditional rigid counterparts. This effect is explained by a wavy chain model based on the magnetic dipole-dipole interaction and demagnetizing factor. To facilitate practical applications, we further invented a textile magnetoelastic generator (MEG), weaving the 1D soft fibers with conductive yarns to couple the observed magnetoelastic effect with magnetic induction, which paves a new way for biomechanical-to-electrical energy conversion with short-circuit current density of 0.63 mA cm−2, internal impedance of 180 Ω, and intrinsic waterproofness. Textile MEG was demonstrated to convert the arterial pulse into electrical signals with a low detection limit of 0.05 kPa, even with heavy perspiration or in underwater situations without encapsulations., The authors invented a textile magnetoelastic generator, weaving 1D soft fibers with conductive yarns to couple the observed magnetoelastic effect with magnetic induction, which paves a new way for biomechanical-to-electrical energy conversion.

Wearable bioelectronics for continuous and reliable pulse wave monitoring against body motion and perspiration remains a great challenge and highly desired. Here, a low-cost, lightweight, and mechanically durable textile triboelectric sensor that can convert subtle skin deformation caused by arterial pulsatility into electricity for high-fidelity and continuous pulse waveform monitoring in an ambulatory and sweaty setting is developed. The sensor holds a signal-to-noise ratio of 23.3 dB, a response time of 40 ms, and a sensitivity of 0.21 μA kPa(−1). With the assistance of machine learning algorithms, the textile triboelectric sensor can continuously and precisely measure systolic and diastolic pressure, and the accuracy is validated via a commercial blood pressure cuff at the hospital. Additionally, a customized cellphone application (APP) based on built-in algorithm is developed for one-click health data sharing and data-driven cardiovascular diagnosis. The textile triboelectric sensor enabled wireless biomonitoring system is expected to offer a practical paradigm for continuous and personalized cardiovascular system characterization in the era of the Internet of Things.

Silica aerogels are prone to be destroyed due to their brittleness and low mechanical properties, which limits their applications. To break the unfavorable situation, we presented a scalable and facile approach to assemble blocky silica-reduced graphene oxide (SiO2-rGO) hybrid sponges by atmospheric pressure drying technique. Briefly, ungelled silica solution from two-step sol-gel of tetraethoxysilane (TEOS), was incorporated into compressible graphene sponge (CGS). Different silicon concentration ratios had great influence on the performance of hybrid sponges. When VTEOS: Vethanol was fixed at 1:15, the sample had good flexibility and could absorb 8.5–10.2 times its own mass of solvents, but the adsorption efficiency slightly decreased with the increase of the number of experiments. When VTEOS: Vethanol was fixed at 4:7, the SiO2-rGO hybrid sponges exhibited unbroken shape, low volume shrinkage (24%), large specific surface area (803.351 m2/g), and high mass retention (83.64%) at 790 °C of thermal treatment. Moreover, they could support approximately 146 times their weight without structural damage, and possess excellent hydrophobicity with 129 ± 1° of water contact angle. These superior properties enable SiO2-rGO hybrid sponges to exhibit highly efficient absorption of oils and toxic solvents, to be regenerated (10 times) with the full release of adsorbates by heat treatment.

Forthcoming wearable and portable electronics such as Google Glass and smart cloths urgently require the development of foldable Li-ion batteries (LIBs) to fit diverse shapes, operate under repeated folding motions, and facilitate collapsible designs. Here we report for the first time a hydrothermal reduction synthesis of a very thin (5-μm-thick) Ni film with inverted pyramids (NFIP); the resultant film exhibits an extremely high conductivity of 1.25 × 105 S cm-1. This inverted pyramid design enables the realization of an NFIP whose resistance deviates by 0.19% and 0.72% from its initial value after 22,000 (outward) and 18,000 (inward) folding cycles. The foldable LIB show a capacity retention of 98.4% at 20 C after being subjected to 5000 cycles of full folding (180°) compared to that delivered under the initial flat state. We also demonstrate a foldable LIB integrated with a Google Glass model in which the battery powers an LED lamp during 9000 cycles of folding (90°) motions.

Varieties of nanostructured SnO2 have been widely investigated as promising anode material for next generation lithium-ion batteries (LIBs). However, traditional nanostructures suffer from re-agglomeration and excessive side reactions, which lead to low coulombic efficiency, poor rate performance and dramatic capacity decay. Here we develop an easy and robust strategy to fabricate carbon framework microbelts anchoring ultrafine SnO2 nanoparticles (U-SnO2 NPs@ CF-MBs), which takes advantage of the synergistic effect between high conductivity of large-size carbon framework and high activity of ultrafine SnO2 nanoparticles. The as-fabricated U-SnO2 NPs@C-BsF composite deliver high capacity of 925 mAh g−1 after 250 cycles at current density of 200 mA g−1, high rate capacity of 464 mAh g−1 at a high current density of 5000 mA g−1 and long cycle performance of 788 mAh g−1 after 1000 cycles at current density of 1500 mA g−1 in half cells. When applied in a full cell by coupling with a LiCoO2 cathode, the fabricated U-SnO2 NPs@ CF-MBs composite full cells keep a high capacity of 510 mAh g−1 after 80 cycles. Notably, the electrode exhibit two platforms located at 3.3 and 2.6 V, which indicate that the conversion between SnO2 and Sn is also highly reversible in full cells. The excellent lithium storage of large-scale U-SnO2 NPs@ CF-MBs ensures its great promise for commercial utilization in the future LIBs.

The magnetoelastic effect—the variation of the magnetic properties of a material under mechanical stress—is usually observed in rigid alloys, whose mechanical modulus is significantly different from that of human tissues, thus limiting their use in bioelectronics applications. Here, we observed a giant magnetoelastic effect in a soft system based on micromagnets dispersed in a silicone matrix, reaching a magnetomechanical coupling factor indicating up to four times more enhancement than in rigid counterparts. The results are interpreted using a wavy chain model, showing how mechanical stress changes the micromagnets’ spacing and dipole alignment, thus altering the magnetic field generated by the composite. Combined with liquid-metal coils patterned on polydimethylsiloxane working as a magnetic induction layer, the soft magnetoelastic composite is used for stretchable and water-resistant magnetoelastic generators adhering conformably to human skin. Such devices can be used as wearable or implantable power generators and biomedical sensors, opening alternative avenues for human-body-centred applications. Micromagnets dispersed in a polymer matrix are used to realize a soft magnetoelastic generator with high magnetomechanical coupling factor, used for wearable and implantable power generation and sensing applications.

In order to grasp the effect of soft and hard coal pore structure on gas adsorption characteristics, based on fractal geometry theory, low-temperature nitrogen adsorption and constant temperature adsorption test methods are used to test the pore structure characteristics of soft coal and its influence on gas adsorption characteristics. We used box dimension algorithm to measure the fractal dimension and distribution of coal sample microstructure. The research results show that the initial nitrogen adsorption capacity of soft coal is greater than that of hard coal, and the adsorption hysteresis loop of soft coal is more obvious than that of hard coal. And the adsorption curve rises faster in the high relative pressure section. The specific surface area and pore volume of soft coal are larger than those of hard coal. The number of pores is much larger than that of hard coal. In particular, the superposition of the adsorption force field in the micropores and the diffusion in the mesopores enhance the adsorption potential of soft coal. Introducing the concept of adsorption residence time, it is concluded that more adsorption sites on the surface of soft coal make the adsorption and residence time of gas on the surface of soft coal longer. Fractal characteristics of the soft coal surface are more obvious. The saturated adsorption capacity of soft coal and the rate of reaching saturation adsorption are both greater than those of hard coal. The research results of this manuscript will provide a theoretical basis for in-depth analysis of the adsorption/desorption mechanism of coalbed methane in soft coal seams and the formulation of practical coalbed methane control measures.

Antimony trisulfide (Sb2S3) is a prospective electrode material for lithium-ion batteries (LIBs) because of its thermal stability, low price, and high specific capacity. However, the commercialization of Sb2S3 as an anode material is greatly hindered by its poor electronic conductivity and massive volume variation during charge/discharge cycles. Moreover, growing demand in reducing greenhouse gas emission requires the material preparation process to be pollution free and highly energy efficient. Herein, we introduce, for the first time, an eco-friendly and highly efficient one-step annealing method to construct a three-dimensional (3D) flexible conductive network and buffer matrix for N-doped Sb2S3-carbon fibers (NSSCs) as a high-performance anode. It is assembled by mixing sulfur and antimony in the atomicity level with a stoichiometric ratio as the electrospinning precursor and then annealed in a sealed quartz tube to assure the high atom utilization of nitrogen and sulfur. Benefiting from the 3D structure and compositional advantages, the NSSC electrode with improved conductivity and carbon buffer matrix exhibits superior Li-storage performance. As a result, this work not only promotes the commercialization of antimony trisulfide but also points out a general eco-friendly method, which can be widely applied to synthesize a variety of flexible metal sulfides and metal nitrides with high atom utilization and zero discharge.

The triboelectric nanogenerator (TENG) has been proved to be a green and efficient energy harnessing technology for electricity generation from ambient mechanical motions based on its ability to leverage the triboelectrification process. Enhancing TENG output performance through rational structural design still triggers increasing research interest. Here, we report a ternary electrification layered architecture beyond the current binary TENG systems, with improved performance for mechanical energy harvesting. Introducing a ternary Kapton layer into the traditional binary electrification layered architecture of TENGs consisting of copper and fluorinated ethylene propylene, yields a 2.5 times enhancement of peak power output, representing a 6.29-fold increase compared to the TENG composed of copper and Kapton. A wide-range of material configurations were systematically tested using this ternary electrification layered architecture to prove its practical effectiveness. The ternary electrification layered architecture invented in this work provides an alternative strategy to enhance TENG output performance, which represents a solid step for TENGs application in high-performance mechanical energy harvesting.

Two dimensional (2D) porous materials have great potential in electrochemical energy conversion and storage. Over the past five years, our research group has focused on Simple, Mass, Homogeneous and Repeatable Synthesis of various 2D porous materials and their applications for electrochemical energy storage especially for supercapacitors (SCs). During the experimental process, through precisely controlling the experimental parameters, such as reaction species, molar ratio of different ions, concentration, pH value of reaction solution, heating temperature, and reaction time, we have successfully achieved the control of crystal structure, composition, crystallinity, morphology, and size of these 2D porous materials including transition metal oxides (TMOs), transition metal hydroxides (TMHOs), transition metal oxalates (TMOXs), transition metal coordination complexes (TMCCs) and carbon materials, as well as their derivatives and composites. We have also named some of them with CQU-Chen (CQU is the initialism of Chongqing University, Chen is the last name of Lingyun Chen), such as CQU-Chen-Co-O-1, CQU-Chen-Ni-O-H-1, CQU-Chen-Zn-Co-O-1, CQU-Chen-Zn-Co-O-2, CQU-Chen-OA-Co-2-1, CQU-Chen-Co-OA-1, CQU-Chen-Ni-OA-1, CQU-Chen-Gly-Co-3-1, CQU-Chen-Gly-Ni-2-1, CQU-Chen-Gly-Co-Ni-1, etc. The introduction of 2D porous materials as electrode materials for SCs improves the energy storage performances. These materials provide a large number of active sites for ion adsorption, supply plentiful channels for fast ion transport and boost electrical conductivity and facilitate electron transportation and ion penetration. The unique 2D porous structures review is mainly devoted to the introduction of our contribution in the 2D porous nanostructured materials for SC. Finally, the further directions about the preparation of 2D porous materials and electrochemical energy conversion and storage applications are also included.

The efficient conversion of ultrasound into electrical energy remains a highly desirable wireless powering solution, with potentially profound ramifications in energy transfer across virtually all industrial fields, especially for implantable medical devices. Triboelectric nanogenerators have been shown to effectively carry out ultrasound energy transduction, though efficiency remains poor. Here, we devise a computational model to investigate the optimal triboelectric nanogenerator irradiation conditions, including frequency, probe distance, size, and design, as represented by irradiated triboelectric surface area displacement. Our investigation may set the foundations for the establishment of a standardized protocol for efficient ultrasound mechanical energy harvesting. This holds considerable significance and could be paramount in designing an ever-growing number of applicative solutions in wireless energy transfer, providing a scalable, cost effective and time saving solution in the development of implantable medical devices.

Here, we demonstrate the in situ growth of SnO2 nanosheets on a freestanding carbonized eggshell membrane (CEM), which provides three-dimensional, bicontinuous electron and ion transport pathways through a massively interconnected carbon fiber skeleton and interpenetrated pore network, respectively. This CEM has other advantages such as the ability to alleviate mechanical stress during cycling as a buffer matrix. When used as an additive-free anode in a sodium-ion battery, SnO2 nanosheets can realize a complete electrochemical reaction and maintain good cycling stability with the help of a CEM. For instance, SnO2 nanosheets delivered a high reversible capacity of 656 mA h g–1 in the 5th cycle at 0.1 A g–1, approaching 98% of its theoretical specific capacity, and maintained a high reversible specific capacity of 420 mA h g–1 after 200 cycles at 0.2 A g–1.

In this paper, a novel molecularly imprinted electrochemical sensor (MIECS) based on a glassy carbon electrode (GCE) modified with graphene quantum dots (GQDs) coated on hollow nickel nanospheres (hNiNS) for the rapid determination of bisphenol S (BPS) was proposed for the first time. HNiNS and GQDs as electrode modifications were used to enlarge the active area and electron-transport ability for amplifying the sensor signal, while molecularly imprinted polymer (MIP) film was electropolymerized by using pyrrole as monomer and BPS as template to detect BPS via cyclic voltammetry (CV). Scanning electron microscope (SEM), energy-dispersive spectrometry (EDS), CV and differential pulse voltammetry (DPV) were employed to characterize the fabricated sensor. Experimental conditions, such as molar ratio of monomer to template, electropolymerization cycles, pH, incubation time and elution time were optimized. The DPV response of the MIECS to BPS was obtained in the linear range from 0.1 to 50μM with a low limit of detection (LOD) of 0.03μM (S/N = 3) under the optimized conditions. The MIECS exhibited excellent response towards BPS with high sensitivity, selectivity, good reproducibility, and stability. In addition, the proposed MIECS was also successfully applied for the determination of BPS in the plastic samples with simple sample pretreatment.

A key challenge in the development of electrochemical energy storage (EES) is the design and engineering of electrode materials for electrochemical reactions. Transition metal oxalates (TMOxs) have been widely used in various EES applications due to their low cost, simple synthesis, and excellent electrochemical performance. In this review, the recent advances in the design and engineering of transition metal oxalate-based micro- and nanomaterials for EES are summarized. Specifically, the survey will focus on three types of micro- and nano-scale TMOxs (monometallic, bimetallic, and trimetallic TMOxs), their composites (TMOx-metal oxide, TMOx-hydroxide, TMOx-GO, and TMOx-MOFs composites), and derivatives, including transition metal oxides (TiO2, V2O5, MnxOy, Co3O4, NiO, CuO, and Nb2O5), multi-transition metal oxides (MCo2O4 (M = Ni, Cu, and Zn), NiMn2O4, and NxOy-MxOy), transition metal sulfide (NiS2), and carbon materials (ordinary carbon, GO and their composites), within the context of their intrinsic structure and corresponding electrochemical performance. A range of experimental variables will be carefully analyzed, such as sample synthesis, crystal structure, and electrochemical reaction mechanism. The applications of these materials as EES electrodes are then featured for supercapacitors (SCs) and lithium-ion batteries (LIBs). We conclude the review with a perspective of future research prospects and challenges.

Doping polymers with ceramic nanofillers is a widely-adopted routine for developing high-performance nanocomposites. However, improving the interaction between the nanofillers and the polymer matrix for an enhanced composite performance remains highly desired in the community. Herein, we systematically investigated the barium titanate doped polyvinylidene fluoride (BTO/PVDF) piezoelectric nanocomposites in a fiber form through comprehensive phase-field simulation and detailed experimental characterization. Both experimental and theoretical results indicated that the introduction of 2.15 vol% polydopamine (PDA) coating on the BTO nanoparticles could remarkably promote the local all-trans conformation and modulus match at the nanofillers-polymer interface, giving rise to the maximum piezoelectric charge coefficient and piezoelectric voltage coefficient as well as mechanical stiffness. To demonstrate the effectiveness of the PDA modification, a polydopamine modified nonwoven piezoelectric (PMNP) textile was constructed based on the composite fiber, which showed outstanding sensitivity and long-term stability for wearable biomonitoring, including limb motion detection, facial expression identification, respiratory monitoring, and human-machine interfacing. This work endows insight into the fundamental mechanism of the interfacial coupling effect in polymer composites for the development of high-performance wearable textile bioelectronics.

Improving the performance of advanced energy conversion and storage equipments has always been a key issue in energy research. In recent years, layered double hydroxides (LDHs), especially NiFe-LDHs, have been widely used in catalysts, photoactive materials, acid absorbers, supercapacitors and other fields because of their versatility and high efficiency. In addition, due to its unique layered structure and fascinating characteristics, two-dimensional (2D) NiFe-LDHs materials show excellent performance in various energy conversion and storage fields. This review concentrated on rationally designing of 2D NiFe-LDHs by various methods including co-precipitation method, hydrothermal treat, ion exchange, and electrodeposition method. We describe the morphology and interfacial design of 2D NiFe-LDHs and their composites, among which these 2D materials usually take on nanoscale shapes and they adopt shell-core structure, heterostructure, and others. After that this paper expounds advanced characterization technologies to analyse these materials. This review has summarized their electrochemical energy conversion and storage applications. Finally, the future challenges and prospects of 2D NiFe-LDHs materials in energy storage devices and other fields are summarized.

Pervasive and portable energy solutions are highly desired in the era of Internet of Things for powering wide-range distributed electronics. Human body contains renewable biomechanical energy sources, which could be harnessed for sustainable electricity generation as portable power sources for wearable bioelectronics. Herein, we propose an ultralow-cost, efficient, portable hand-driven triboelectric nanogenerator (HD-TENG) enabled by whirligig spinning to harvest energy from low-frequency and linear human biomechanical motions. Remarkably, the operating HD-TENG could easily achieve a rotational speed of over 10,000 rpm with a gentle hand stretching in a linear and periodic manner. The reported HD-TENG was demonstrated to charge a 220 μ F commercial capacitor up to 3 V in less than 80 s, and continuously drive a smart bracelet for health monitoring, and a portable MPEG-1 audio layer III for music playing. With a collection features of high output power, light weight, excellent portability, ease of transport, cost-effectiveness, and environmental friendliness, the ingeniously designed HD-TENG represents a convenient green power supply approach for wearable bioelectronics in the era of Internet of Things.

Given that catechol and nitrite can be easily released into the environment and cause serious damage to our physical and ecological environment, it is necessary to develop a fast and reliable detection method for catechol and nitrite analysis. In our work, an electrochemical catechol and nitrite sensor was created based on gold nanoparticles (AuNPs) deposited on chitosan@N,S co-doped multiwalled carbon nanotubes (CS@N,S co-doped MWCNTS) composite modified glassy carbon electrode. The preliminary prepared composite materials were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The AuNPs/CS@N,S co-doped MWCNTS modified electrode shows a good linear relationship between 1 μmol·L–1 (μM) and 5000 μM for catechol, and the detection limit was calculated as 0.2 μM. For nitrite the linear relationship was 1–7000 μM with the detection limit of 0.2 μM. The sensitivity of the created sensor was evalua...

SiCp/Cu composites with a compact microstructure were successfully fabricated by vacuum hot-pressing method. In order to suppress the detrimental interfacial reactions and ameliorate the interfacial bonding between copper and silicon carbide, molybdenum coating was deposited on the surface of silicon carbide by magnetron sputtering method and crystallized heat-treatment. The effects of the interfacial design on the thermo-physical properties of SiCp/Cu composites were studied in detail. Thermal conductivity and expansion test results showed that silicon carbide particles coated with uniform and compact molybdenum coating have improved the comprehensive thermal properties of the SiCp/Cu composites. Furthermore, the adhesion of the interface between silicon carbide and copper was significantly strengthened after molybdenum coating. SiCp/Cu composites with a maximum thermal conductivity of 274.056 W/(m·K) and a coefficient of thermal expansion of 9 ppm/K were successfully prepared when the volume of silicon carbide was about 50%, and these SiCp/Cu composites have potential applications for the electronic packageing of the high integration electronic devices.

In this brief, a low-temperature microwave annealing (MWA) method is demonstrated for the formation of ohmic contact to AlN/GaN high electron mobility transistors (HEMTs) for the first time. Compared with the traditional rapid thermal annealing (RTA) technique, MWA-HEMT can achieve a comparable low ohmic contact resistance with much smoother surface of ohmic contacts. Transmission electron microscopy results show that no direct current path connecting the 2-D electron gas and the metal is formed. Temperature-dependent contact resistance measurement indicates that field emission tunneling dominates the current transport mechanism in ohmic contact formation. The maximum dc output current density of 1.4 A/mm and the peak extrinsic transconductance ( ${G}_{\textsf {m}}$ ) of 270 mS/mm are measured on ${2} \times {8} \,\,{\sf \mu } $ $m^2$ gate MWA-HEMTs. Besides, MWA-HEMTs have higher ${I}_{ \mathrm{ ON}}/{I}_{ \mathrm{ OFF}}$ ratio due to the lower gate leakage current than that of RTA-HEMTs.

We propose a method of modelling the infiltration process of a liquid aluminium matrix into a porous silicon carbide particle (SiCp) preform based on porous medium geometry obtained from scanning electron microscopy (SEM) images. Our simulation illustrates that via a pore-scale, two-phase flow model, an improved description of the flow structure in the porous medium can be obtained compared with the description offered by traditional methods, such as those based on the capillarity and wetting conditions of porous media and Darcy’s law, the Brinkman equations or Richards’ equation. Simultaneously, we validate the proposed model by comparing simulated and experimental data. In particular, the simulation results successfully capture several important features of a pore-scale, two-phase flow: the evolution of the flow front during the infiltration process, the most probable locations of potential defects, the preferential flow paths, the pressure distribution, the velocity field and the permeability of the porous SiCp preform.

Red phosphorus (RP) has attracted extensive attention as an anodic material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of 2596 mA h g− 1 and earth abundance. However, the facile and large-scale preparation of the red phosphorus nanomaterials via a solution synthesis remains a challenge. Herein, we develop a simple and facile solution method to prepare red phosphorus nanoparticles (RP NPs). PCl3 readily reacts with HSiCl3 in the presence of amines at room temperature to produce amorphous RP NPs with sizes about 100–200 nm in high yields. When used as an anode for rechargeable lithium ion battery, the RP NP electrode exhibits good electrochemical performance with a reversible capacity of 1380 mA h g− 1 after 100 cycles at a current density of 100 mA g− 1, and Coulombic efficiencies reaching almost 100% for each cycle. The study shows that this solution synthesis is a facile and convenient approach for large-scale production of RP NP materials for use in high-performance Li-ion batteries. Electronic supplementary material The online version of this article (10.1186/s11671-018-2770-4) contains supplementary material, which is available to authorized users.

Carbon is a fascinating element that can be found in a wide spectrum of materials and plays a significant role in diverse disciplines across the scientific community. Carbon nanomaterials take many forms with numerous applications. Controllably tailoring carbon nanomaterials at the molecular scale can be considered as a basic innovation yet remains a significant challenge because of carbon’s intrinsic structural and chemical stability. Herein, we report a molecular scissor to efficiently tailor carbon nanomaterials of different dimensions at a molecular level. By using the Mg/Zn bimetallic effect and CO2 molecules, a molecular scissor was invented to engineer the surface of carbon nanomaterials with highly interconnected graphene pillared superstructures. The molecular scissor redesigned the carbon materials with improved surface properties for use in various applications. For energy storage application, both ultrahigh surface area and conductivity can be achieved concurrently with substantial ion-reserved accommodation and rapid mass-transfer expressway. As a demonstration, a flexible solid-state supercapacitor based on the surface-tailored carbon fiber was developed with Polyvinyl alcohol(PVA)/Na2SO4 gel electrolytes. It delivered a remarkably high energy density of 4.63 mW h cm–3 at a power density of 3520 mW cm–3. This work paves a new way to reinvent carbon materials at the molecular scale and promote their applications for energy storage, sensing, environmental remediation, and healthcare.

Direct alcohol fuel cell (DAFC) exhibits multiple unique advantages, such as high energy conversion efficiency, low cost, ready availability of fuels, minimal environmental pollution, and ease of operation, and has found diverse applications as a small, micro mobile power supply. A critical challenge for the development of DAFC is the design and engineering of effective anode catalysts, where electrooxidation of alcohols occurs. Within this context, two-dimensional (2D) electrocatalysts represent a viable option, due to their unique materials properties, such as large surface area, ease of charge migration and mass transfer, and mechanical robustness during electrochemical reactions. In this review, we summarize recent breakthroughs in the structural engineering of a range of 2D functional nanomaterials, including noble metals and alloys, metal oxides/hydroxides, metal carbides, and precious metal-based nanocomposites, in the electrocatalytic oxidation of alcohols (primarily methanol and ethanol), within the context of reaction mechanisms, and include a perspective highlighting the promises and challenges in future research.

We have fabricated the Cu (50 nm)/Nb–Ni (5 nm)/Si heterostructures, annealed at various temperatures up to 800 °C in a high vacuum system, to investigate the barrier performance of the ultrathin amorphous Nb–Ni film between Cu and Si. No impurity peaks are observed from the X-ray diffraction patterns of the Cu/Nb–Ni/Si heterostructures annealed up to 800 °C. The island-like surface is observed for the 800 °C annealed sample, indicating the failure of the Nb–Ni barrier layer, which is attributed to agglomeration of Cu film resulting from the dewetting of Cu with the underlying Nb–Ni layer during high temperature annealing. The activation energy for Cu dewetting with Nb–Ni layer is estimated to be 0.86 eV. Our result demonstrates that ultra-thin amorphous Nb–Ni film can be an ideal diffusion barrier layer for Cu interconnection.

Developing lightweight, flexible, and foldable electrodes with decent mechanical durability and electrochemical activity is a highly desirable goal for solid-state electrochemical energy storage devices yet remains a formidable challenge to overcome. Herein, we invent a freestanding robust PANI membrane via introducing the dynamic boronate bond to bridge rigid PANI chains with complaint polyvinyl alcohol (PVA) chains. The resultant PANI/PVA membrane (PPM) exhibits remarkable elasticity (17.8% strain) along with excellent tensile strength (33.7 MPa), outperforming the majority of existing state-of-the-art flexible electrochemical PANI membranes. Additionally, the PPM can be further assembled into a wearable solid-state supercapacitor with high electrochemical performance as well as decent mechanical durability. The lightweight, flexible, and foldable PANI membrane represents a great advancement in electrode materials for next-generation wearable solid-state electrochemical energy storage devices.

Approximately 22% of the 86 million people in the United States living with prediabetes are unaware of their condition. Detection of acetone in human respiration offers an effective and painless approach for the diagnosis of prediabetes. In this work, a wearable active acetone biosensor employing chitosan and reduced graphene oxide (RGO) as sensitive materials was developed to non-invasively diagnose prediabetes. When operated under 97.3% relative humidity at room temperature, the prepared chitosan and RGO composite film-based sensor exhibited a good sensing response of 27.89% under 10 ppm acetone in respiratory gases, which is about 5 times higher than the sensing response of pure chitosan film-based devices. In addition, finite element analysis and phase-field simulation were conducted to provide theoretical support for the active sensing mechanism. This work not only presents a wirelessly powered wearable active acetone biosensor, but also paves the way for a new method of non-invasive prediabetes diagnosis.

Under the time theme of the energy crisis and environmental pollution, a great deal of attention has been devoted to the field of supercapacitors (SCs) for relieving this situation. Two-dimensional (2D) materials show great potential in various energy storage fields due to their unique and attractive characteristics. Especially, different types of 2D spinel structured Co-based MCo2O4 (M = Co, Ni, Zn, Cu, Fe, and Mn) materials are supposed to be promising candidates of electrode materials for SCs, which ascribes to their natural abundance and superior electrochemical performances including relatively high electron conductivity, rich electroactive sites, high specific capacitance, and good cycling stability. Moreover, 2D spinel structured Co-based materials can incorporate with other nanomaterials to form various diverse composites such as heterostructures, carbonaceous composites, transition metal oxide (TMO) composites, transition metal hydroxide (TMH) composites, transition metal sulfide (TMS) composites, transition metal phosphide (TMP) composites, and ternary composites, which can deliver satisfactory electrochemical performances. In this review, we highlighted the 2D spinel structured Co-based materials and their composites for SC applications. Finally, the future challenges and outlooks of 2D spinel structured Co-based materials in energy storage devices were also discussed.

The shock resistance of ship piping systems is very difficult to study owing to the large scales of such systems, and the high level and variability of the impact loading involved. To address these issues, the present work establishes a numerical model of pipe systems based on multi-span beam bending moment theory. An analysis of the bending moments of different multi-span continuous beams under static loading demonstrates that the simplified model employing just five spans provides a bending moment for target equal diameter straight tube (EDST) segments that deviates from theoretical calculations by less than 1%. Moreover, the bending moments obtained by the five-span model for a target EDST segment deviate by only about 4% from corresponding results obtained by the finite element (FE) method under both uniformly distributed static loading and complex static loading. The proposed simplified five-span model is then employed to calculate the stress responses obtained at individual critical points in a complex piping system under impact loading. The results obtained deviate at most by less than 15% from corresponding results obtained from the FE method based on the overall piping system model. Moreover, the average deviation for all critical points considered was only 5.87%. The results show that the shock response obtained using the simplified five-span model is essentially equivalent to that of the complex model. The proposed simplified five-span method is thereby demonstrated to be reasonable for simplifying large-scale complex piping systems when conducting shock resistance research.

Silicon carbide (SiC) reinforced aluminum composites with three dimensional interpenetrating network structure (3D-SiC/Al) were fabricated by the gas pressure infiltration method, and their thermophysical properties were investigated. The results show that the geometry of SiC reinforcement has a significant impact on the thermophysical properties of the composites. Continuous SiC reinforced aluminum composites (3D-SiC/Al) have higher thermal conductivities and lower coefficients of thermal expansion (CETs) than those of particulate SiC reinforced aluminum composites (SiC p /Al) with the same SiC volume fraction. The co-continuous structures of both the SiC reinforcement and the Al matrix in 3D-SiC/Al can be the reason behind this phenomena. As a result, when SiC volume fraction values were the same, 3D-SiC/Al composites will be more suitable for electronic packaging applications comparing with SiC p /Al composite.

Laser-weldable Si p –SiC p /Al hybrid composites with high volume fraction (60%–65%) of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Si p –SiC p /Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Si p /Al layer and SiC p /Al layer was homogeneous and continuous. Further investigation revealed that the Si p –SiC p /Al hybrid composites possessed low density (2.96 g/cm 3 ), high gas tightness (1.0 mPa·cm 3 )/s), excellent thermal management function as a result of high thermal conductivity (194 W/(m·K) and low coefficient of thermal expansion (7.0×10 −6 K −1 ). Additionally, Si p –SiC p /Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding (48 mPa·cm 3 )/s) can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.