Microstructure-Reconfigured Graphene Oxide Aerogel Metamaterials for Ultrarobust Directional Sensing at Human-Machine Interfaces.

Graphene aerogels hold huge promise for the development of high-performance pressure sensors for future human-machine interfaces due to their ordered microstructure and conductive network. However, their application is hindered by the limited strain sensing range caused by the intrinsic stiffness of the porous microstructure. Herein, an anisotropic cross-linked chitosan and reduced graphene oxide (CCS-rGO) aerogel metamaterial is realized by reconfiguring the microstructure from a honeycomb to a buckling structure at the dedicated cross-section plane. The reconfigured CCS-rGO aerogel shows directional hyperelasticity with extraordinary durability (no obvious structural damage after 20 000 cycles at a directional compressive strain of ≤0.7). The CCS-rGO aerogel pressure sensor exhibits an ultrahigh sensitivity of 121.45 kPa-1, an unprecedented sensing range, and robust mechanical and electrical performance. The aerogel sensors are demonstrated to monitor human motions, control robotic hands, and even integrate into a flexible keyboard to play music, which opens a wide application potential in future human-machine interfaces.

MXene/Nitrogen-Doped Carbon Nanosheet Scaffold Electrode toward High-Performance Solid-State Zinc Ion Supercapacitor.

While MXene is widely used as an electrode material for supercapacitor, the intrinsic limitation of stacking caused by the interlayer van der Waals forces has yet to be overcome. In this work, a strategy is proposed to fabricate a composite scaffold electrode (MCN) by intercalating MXene with highly nitrogen-doped carbon nanosheets (CN). The 2D structured CN, thermally converted and pickling from Zn-hexamine (Zn-HMT), serves as a spacer that effectively prevents the stacking of MXene and contributes to a hierarchically scaffolded structure, which is conducive to ion movement; meanwhile, the high nitrogen-doping of CN tunes the electronic structure of MCN to facilitate charge transfer and providing additional pseudocapacitance. As a result, the MCN50 composite electrode achieves a high specific capacitance of 418.4 F g-1 at 1 A g-1. The assembled symmetric supercapacitor delivers a corresponding power density of 1658.9 W kg-1 and an energy density of 30.8 Wh kg-1. The all-solid-state zinc ion supercapacitor demonstrates a superior energy density of 68.4 Wh kg-1 and a power density of 403.5 W kg-1 and shows a high capacitance retention of 93% after 8000 charge-discharge cycles. This study sheds a new light on the design and development of novel MXene-based composite electrodes for high performance all-solid-state zinc ion supercapacitor.

Enhanced Interfacial Electron Transfer in Photocatalyst-Natural Enzyme Coupled Artificial Photosynthesis System: Tuning Strategies and Molecular Simulations.

Laccase is capable of catalyzing a vast array of reactions, but its low redox potential limits its potential applications. The use of photocatalytic materials offers a solution to this problem by converting absorbed visible light into electrons to facilitate enzyme catalysis. Herein, MIL-53(Fe) and NH2-MIL-53(Fe) serve as both light absorbers and enzyme immobilization carriers, and laccase is employed for solar-driven chemical conversion. Electron spin resonance spectroscopy results confirm that visible light irradiation causes rapid transfer of photogenerated electrons from MOF excitation to T1 Cu(II) of laccase, significantly increasing the degradation rate constant of tetracycline (TC) from 0.0062 to 0.0127 min-1. Conversely, there is only minimal or no electron transfer between MOF and laccase in the physical mixture state. Theoretical calculations demonstrate that the immobilization of laccase's active site and its covalent binding to the metal-organic framework surface augment the coupled system's activity, reducing the active site accessible from 27.8 to 18.1 Å. The constructed photo-enzyme coupled system successfully combines enzyme catalysis' selectivity with photocatalysis's high reactivity, providing a promising solution for solar energy use.

Hydrophobic Multilayered PEG@PAN/MXene/PVDF@SiO2 Composite Film with Excellent Thermal Management and Electromagnetic Interference Shielding for Electronic Devices.

With the rapid development of electronic industry, it's pressing to develop multifunctional electromagnetic interference (EMI) shielding materials to ensure the stable operation of electronic devices. Herein, multilayered flexible PEG@PAN/MXene (Ti3C2Tx)/PVDF@SiO2 (PMF) composite film has been constructed from the level of microstructure design via coaxial electrospinning, coating spraying, and uniaxial electrospinning strategies. Benefiting from the effective encapsulation for PEG and high conductivity of MXene coating, PEG@PAN/MXene composite film with MXene coating loading density of 0.70 mg cm-2 exhibits high thermal energy storage density of 120.77 J g-1 and great EMI shielding performance (EMI SE of 34.409 dB and SSE of 49.086 dB cm3 g-1) in X-band (8-12 GHz). Therefore, this advanced composite film can not only help electronic devices prevent the influence of electromagnetic pollution in the X-band but also play an important role in electronic device thermal management. Additionally, the deposition of nano PVDF@SiO2 fibers (289 ± 128 nm) endowed the PMF composite film with great hydrophobic properties (water contact angle of 126.5°) to ensure the stable working of hydrophilic MXene coating, thereby breaks the limitation of humid application environments. The finding paves a new way for the development of novel multifunctional EMI shielding composite films for electronic devices.

Overview of Inorganic Electrolytes for All-Solid-State Sodium Batteries.

All-solid-state sodium batteries (AS3B) emerged as a strong contender in the global electrochemical energy storage market as a replacement for current lithium-ion batteries (LIB) owing to their high abundance, low cost, high safety, high energy density, and long calendar life. Inorganic electrolytes (IEs) are highly preferred over the conventional liquid and solid polymer electrolytes for sodium-ion batteries (SIBs) due to their high ionic conductivity (∼10-2-10-4 S cm-1), wide potential window (∼5 V), and overall better battery performances. This review discusses the bird's eye view of the recent progress in inorganic electrolytes such as Na-ß"-alumina, NASICON, sulfides, antipervoskites, borohydride-type electrolytes, etc. for AS3Bs. Current state-of-the-art inorganic electrolytes in correlation with their ionic conduction mechanism present challenges and interfacial characteristics that have been critically reviewed in this review. The current challenges associated with the present battery configuration are overlooked, and also the chemical and electrochemical stabilities are emphasized. The substantial solution based on ongoing electrolyte development and promising modification strategies are also suggested.

Modifying Polyvinylidene Chloride Resin with Fluorine Monomer and Cross-Linking Monomers.

Modified polyvinylidene chloride (PVDC) resin was prepared using octafluoropentyl methacrylate and trimethylolpropane trimethacrylate as modifying monomers through seeded emulsion polymerization. The successful incorporation of octafluoropentyl methacrylate into the PVDC resin was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and XPS were utilized to investigate the element distribution in the modified monomer emulsion and the mechanism of monomer modification. The results demonstrated that the fluorine monomer was reacted in the resin, and mainly concentrated on the surface of the resin. The addition of octafluoropentyl methacrylate and trimethylolpropane trimethacrylate improved the water resistance of the resin. Compared to unmodified PVDC resin, the contact angle of the modified PVDC resin increased from 89.46° to 109.51°, and the water resistance at room temperature increased from 120 to 500 h. Furthermore, the modified resin exhibited excellent mechanical properties, thermal stability, and storage stability.

Ammonia energy fraction effect on the combustion and reduced NOX emission of ammonia/diesel dual fuel.

With stringent regulations of internal combustion engine on reducing CO2 emission, ammonia has been used as an alternative fuel. Investigating how engine-related performance is affected by partial ammonia replacement of diesel fuel is essential for understanding the combustion. Therefore, in this study, a three-dimensional numerical simulation model is developed for the burning of two fuels of diesel and ammonia based on relevant parameters (i.e., compression ratio, load, ammonia energy fraction, etc.) in a lab-made diesel engine. The consequences of load and compression proportion on combustion and pollutant emissions are investigated for ammonia energy fractions between 50% and 90%. When the ammonia portion rises, the increased ammonia equivalent ratio causes ammonia to move away from the dilute combustion boundary and accelerates the combustion rate of ammonia. An increase in compression ratio significantly increases the specified thermal performance and combustion efficacy. When the compression ratio is 16, as the ammonia energy fractions increases, due to the increase in the proportion of ammonia, that is, the proportion of nitrogen atoms increases, more NOx is generated during the combustion process. When the ammonia substitution rate is 90%, as the compression ratio increases, the cylinder pressure and temperature increase. The combustion efficiency of ammonia increases, generating more NOx and NOx emissions can reach 0.66 mg/m3. At a compression ratio of 18, the NOx emissions can reach 1.59 mg/m3. However, under medium and low load conditions, as the ammonia fraction increases, the total energy of fuel decreases, and the combustion efficiency of ammonia decreases, resulting in a decrease in the heat released during combustion and a decrease in NOx emissions. When the ammonia substitution rate is 90% and the load is 25%, NOx emissions reach 0.1 mg/m3. This research provides theoretical suggestions for the profitable and use ammonia fuel in internal combustion engines in a clean manner.

Facile Design of Flexible, Strong, and Highly Conductive MXene-Based Composite Films for Multifunctional Applications.

Strong, conductive, and flexible materials with improving ion accessibility have attracted significant attention in electromagnetic interference (EMI) and foldable wearable electronics. However, it still remains a great challenge to realize high performance at the same time for both properties. Herein, a microscale structural design combined with nanostructures strategy to fabricate TOCNF(F)/Ti3 C2 Tx (M)@AgNW(A) composite films via a facile vacuum filtration process followed by hot pressing (TOCNF = TEMPO-oxidized cellulose nanofibrils, NW = nanowires) is described. The comparison reveals that different microscale structures can significantly influence the properties of thin films, especially their electrochemical properties. Impressively, the ultrathin MA/F/MA film with enhanced layer in the middle exhibits an excellent tensile strength of 107.9 MPa, an outstanding electrical conductivity of 8.4 × 106 S m-1 , and a high SSE/t of 26 014.52 dB cm2 g-1 . The assembled asymmetric MA/F/MA//TOCNF@CNT (carbon nanotubes) supercapacitor leads to a significantly high areal energy density of 49.08 µWh cm-2 at a power density of 777.26 µW cm-2 . This study proposes an effective strategy to circumvent the trade-off between EMI performance and electrochemical properties, providing an inspiration for the fabrication of multifunctional films for a wide variety of applications in aerospace, national defense, precision instruments, and next-generation electronics.

A Multifunctional Asymmetric Fabric for Sustained Electricity Generation from Multiple Sources and Simultaneous Solar Steam Generation.

Harvesting electrical energy from water and moisture has emerged as a novel ecofriendly energy conversion technology. Herein, a multifunctional asymmetric polyaniline/carbon nanotubes/poly(vinyl alcohol) (APCP) that can produce electric energy from both saline water and moisture and generate fresh water simultaneously is developed. The constructed APCP possesses a negatively charged porous structure that allows continuous generation of protons and ion diffusion through the material, and a hydrophilicity-hydrophobic interface which results in a constant potential difference and sustainable output. A single APCP can maintain stable output for over 130 h and preserve a high voltage of 0.61 V, current of 81 µA, and power density of 82.4 µW cm-3 with 0.15 cm3 unit size in the water-induced electricity generation process. When harvesting moisture energy, the APCP creates dry-wet asymmetries and triggers the spontaneous development of electrical double layer with a current density of 1.25 mA cm-3 , sufficient to power small electronics. A device consisting of four APCP can generate stable electricity of 3.35 V and produce clean water with an evaporation rate of 2.06 kg m-2  h-1 simultaneously. This work provides insights into the fabrication of multifunctional fabrics for multisource energy harvesting and simultaneous solar steam generation.

A Simple and Effective Physical Ball-Milling Strategy to Prepare Super-Tough and Stretchable PVA@MXene@PPy Hydrogel for Flexible Capacitive Electronics.

Biomimetic flexible electronics for E-skin have received increasing attention, due to their ability to sense various movements. However, the development of smart skin-mimic material remains a challenge. Here, a simple and effective approach is reported to fabricate super-tough, stretchable, and self-healing conductive hydrogel consisting of polyvinyl alcohol (PVA), Ti3 C2 Tx MXene nanosheets, and polypyrrole (PPy) (PMP hydrogel). The MXene nanosheets and Fe3+ serve as multifunctional cross-linkers and effective stress transfer centers, to facilitate a considerable high conductivity, super toughness, and ultra-high stretchability (elongation up to 4300%) for the PMP hydrogel with. The hydrogels also exhibit rapid self-healing and repeatable self-adhesive capacity because of the presence of dynamic borate ester bond. The flexible capacitive strain sensor made by PMP hydrogel shows a relatively broad range of strain sensing (up to 400%), with a self-healing feature. The sensor can precisely monitor various human physiological signals, including joint movements, facial expressions, and pulse waves. The PMP hydrogel-based supercapacitor is demonstrated with a high capacitance retention of ≈92.83% and a coulombic efficiency of ≈100%.

The Status of Representative Anode Materials for Lithium-Ion Batteries.

Since the invention of lithium-ion batteries as a rechargeable energy storage system, it has uncommonly promoted the development of society. It has a wide variety of applications in electronic equipment, electric automobiles, hybrid vehicles, and aerospace. As an indispensable component of lithium-ion batteries, anode materials play an essential role in the electrochemical characteristics of lithium-ion batteries. In this review, we described the development from lithium-metal batteries to lithium-ion batteries in detail on the time axis as the first step; This was followed by an introduction to several commonly used anode materials, including graphite, silicon, and transition metal oxide with discussions the charge-discharge mechanism, challenges and corresponding strategies, and a collation of recent interesting work; Finally, three anode materials are summarized and prospected. Hopefully, this review can serve both the newcomers and the predecessors in the field.

An Overview of Metal-Organic Framework Based Electrocatalysts: Design and Synthesis for Electrochemical Hydrogen Evolution, Oxygen Evolution, and Carbon Dioxide Reduction Reactions.

Due to the increasing global energy demands, scarce fossil fuel supplies, and environmental issues, the pursued goals of energy technologies are being sustainable, more efficient, accessible, and produce near zero greenhouse gas emissions. Electrochemical water splitting is considered as a highly viable and eco-friendly energy technology. Further, electrochemical carbon dioxide (CO2 ) reduction reaction (CO2 RR) is a cleaner strategy for CO2 utilization and conversion to stable energy (fuels). One of the critical issues in these cleaner technologies is the development of efficient and economical electrocatalyst. Among various materials, metal-organic frameworks (MOFs) are becoming increasingly popular because of their structural tunability, such as pre- and post- synthetic modifications, flexibility in ligand design and its functional groups, and incorporation of different metal nodes, that allows for the design of suitable MOFs with desired quality required for each process. In this review, the design of MOF was discussed for specific process together with different synthetic methods and their effects on the MOF properties. The MOFs as electrocatalysts were highlighted with their performances from the aspects of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and electrochemical CO2 RR. Finally, the challenges and opportunities in this field are discussed.

Composite film with adjustable number of layers for slow release of humic acid and soil remediation.

In this study, to improve the soil amendment performance of film materials, composite films with the adjustable number of layers and controlled slow-release time were prepared using sodium alginate (SA), chitosan (CS) and activated charcoal (AC) as raw materials. The prepared multilayer films exhibited a wide pH response range and excellent slow-release time. The cumulative release of humic acid (HA) increased from 19.87 ± 0.98% to 66.72 ± 1.06% with increasing the pH from 4.0 to 10.0 after 700 h of slow-release. In addition, after 50 d of remediation in red soil, plantation soil, and saline soil, the NH4+-N, Olsen-P, Olsen-K, and organic matter contents in the three soils were increased by 2.91-28.62 mg/kg, 46.97-70.43 mg/kg, 55.89-77.01 mg/kg, and 12.47-22.52 g/kg, respectively, and were able to provide sustained crop growth promotion effect. This study demonstrates the promising application of multilayer film in soil remediation and agricultural production.

Mechanically-robust electrospun nanocomposite fiber membranes for oil and water separation.

Mechanically-robust nanocomposite membranes have been developed via crosslinking chemistry and electrospinning technique based on the rational selection of dispersed phase materials with high Young's modulus (i.e., graphene and multiwalled carbon nanotubes) and Cassie-Baxter design and used for oil and water separation. Proper selection of dispersed phase materials can enhance the stiffness of nanocomposite fiber membranes while their length has to be larger than their critical length. Chemical modification of the dispersed phase materials with fluorochemcials and their induced roughness were critical to achieve superhydrophobocity. Surface analytic tools including goniometer, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, atomic force microscopy (AFM) and scanning electron microscope (SEM) were applied to characterize the superhydrophobic nanocomposite membranes. An AFM-based nanoindentation technique was used to measure quantitativly the stiffness of the nanocomposite membranes for local region and whole composites, compared with the results by a tensile test technique. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were used to confirm composition and formation of nanocomposite membranes. These membranes demonstrated excellent oil/water separation. This work has potential application in the field of water purification and remediation.

Absorption behavior of polycarboxylate superplasticizer with different molecular structures on montmorillonite.

Polycarboxylate (PCE) is a high performance superplasticizer for modern concrete. With the high quality sand becoming precious, more and more low quality sands are used in concrete. However, low quality sands generally contain a relatively high content of montmorillonite (MMT), which could seriously reduce the efficiency of PCE. In order to develop PCE suitable for concrete with low quality sands, the absorption behavior on MMT of PCE with different side chains and acid/ether ratio was investigated. In order to explore the effect of MMT on PCE, two macromonomers were selected, isoprene glycol ether 400(TPEG400) and isoprene glycol ether 2400 (TPEG2400), to synthesize six long and short side chain comb-type PCEs with acid-ether ratios of 1.5:1, 2.5:1 and 3.5:1, respectively. The MMT tolerance mechanism of comb-type PCE in MMT-containing cement slurry was examined by FT-IR, DLS, TOC and other analysis. The PCE with long side chain is much easier to be inserted into the layered structure of MMT, resulting in intercalation absorption. The absorption amount of two kinds of side chain PCE on the MMT particles decreased as the acid ether ratio increases. PCE with long side chains showed shear-thickening properties in MMT-containing cement slurry, on the contrary, short side chains showed shear-thinning properties.

A Strand Entangled Supramolecular PANI/PAA Hydrogel Enabled Ultra-Stretchable Strain Sensor.

Hydrogel electronics have attracted growing interest for emerging applications in personal healthcare management, human-machine interaction, etc. Herein, a "doping then gelling" strategy to synthesize supramolecular PANI/PAA hydrogel with a specific strand entangled network is proposed, by doping the PANI with acrylic acid (AA) monomers to avoid PANI aggregation. The high-density electrostatic interaction between PAA and PANI chains serves as a dynamic bond to initiate the strand entanglement, enabling PAA/PANI hydrogel with ultra-stretchability (2830%), high breaking strength (120 kPa), and rapid self-healing properties. Moreover, the PAA/PANI hydrogel-based sensor with a high strain sensitivity (gauge factor = 12.63), a rapid responding time (222 ms), and a robust conductivity-based sensing behavior under cyclic stretching is developed. A set of strain sensing applications to precisely monitor human movements is also demonstrated, indicating a promising application prospect as wearable devices.

A Visible Light Driven Photoelectrochemical Chloramphenicol Aptasensor Based on a Gold Nanoparticle-Functionalized 3D Flower-like MoS2/TiO2 Heterostructure.

Developing a photoactive material by combining the characteristics of a wide light response range and effective separation of photogenerated electron-hole pairs remains a huge challenge for the construction of a photoelectrochemical (PEC) sensing platform. Herein, a gold nanoparticle (AuNP)/MoS2/TiO2 composite was prepared through the facile hydrothermal method coupled with an in situ photoreduction technology. Benefiting from both the compositional and structure merits, the composite not only extends the absorption range to visible light but also enhances the photoelectric conversion efficiency by transferring photogenerated electrons into the conduction band of semiconductors from the plasmonic AuNP. Meanwhile, the thiolated aptamers were attached to the surface of AuNP/MoS2/TiO2 composites through the Au-S bonding to construct a visible light driven PEC aptasensor for ultrasensitive detection chloramphenicol (CAP). In the presence of CAP, the aptamers anchored on the surface of the photoactive materials could specifically recognize CAP and interact with it to form a bioaffinity complex with a steric hindrance effect, resulting in the rapid decrease of photocurrent responses. Based on this photocurrent suppression strategy, the constructed PEC aptasensing platform exhibited a high sensitivity with a wide linear range from 5 pM to 100 nM and a low detection limit of 0.5 pM.

Waterwheel-inspired high-performance hybrid electromagnetic-triboelectric nanogenerators based on fluid pipeline energy harvesting for power supply systems and data monitoring.

In this work, a self-powered system based on a triboelectric-electromagnetic hybrid pipeline energy harvesting module is demonstrated. Rabbit fur and poly tetra fluoroethylene (PTFE) are used as triboelectric electrodes to fabricate disk-type soft-contact triboelectric nanogenerators (TENGs) instead of traditional direct-contact TENGs to collect the mechanical energy of water flow and convert it into electrical energy. This design has a stable electrical output and gives an improved durability. Its simple fabrication process enables excellent potential for practical applications in industry. In addition, the hybridization of electromagnetic generator module and TENGs module to form a triboelectric-electromagnetic hybrid nanogenerator (TEHNG) can improve the electrical output performance, especially the current output. TEHNG cannot only power small electronic devices, such as lighting systems, but also collect independent fluid energy and monitor data signals simultaneously in harsh environments, such as fluid energy harvesting in industrial production pipelines and temperature and humidity in fluid environments. This work provides an efficient strategy to harvest multiple energies simultaneously, significantly increasing the yield and promoting the application of TENGs in engineering.

In Situ Synthesis of Uranyl-Imprinted Nanocage for Selective Uranium Recovery from Seawater.

An adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into a multivariate metal-organic framework (MOF) during the synthesis process to guide the in situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO2 (CO)3 ]4- in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g-1 , together with an 18.38 times higher selectivity to vanadium.

Microwave Hydrothermally Synthesized Metal-Organic Framework-5 Derived C-doped ZnO with Enhanced Photocatalytic Degradation of Rhodamine B.

C-doped ZnO particles have been successfully prepared by the calcination using microwave hydrothermally prepared metal-organic framework-5 (MOF-5) as the precursor. MOF-5 was turned into C-doped ZnO through calcination at 500 °C, and its cubic shape was well-maintained. X-ray photoelectron spectroscopic studies confirmed the C-doping in the ZnO. The as-prepared C-doped ZnO demonstrated a Rhodamine B (RhB) degradation efficiency of 98% in 2 h under an solar-simulated light irradiation, much higher than that of C-doped ZnO derived from MOF-5 synthesized by the ordinary hydrothermal method. The trapping experiment revealed that the crucial factors in the RhB removal were photogenerated h+ and •O2-.