Precisely Controlled Polymerization of Two-Dimensional Conducting Polymers in Quasi-Liquid Layer Enables Ultrahigh Sensing Performance.

Gas sensors based on conducting polymers offer great potential for high-performance room temperature applications due to their cost-effectiveness, high-sensitivity, and operational advantage. However, their current performance is limited by the deficiency of control in conventional polymerization methods, leading to poor crystallinity and inconsistent material properties. Here, the quasi-liquid layer (QLL) on the ice surface acts as a self-regulating nano-reactor for precise control of thermodynamics and kinetics in the polymerization, resulting in a 7.62 nm thick two-dimensional (2D) polyaniline (PANI) film matching the QLL thickness. The ultra-thin film optimizes the exposure of active sites, enhancing the detection of analyte gases at low concentrations. It is validated by fabricating a chemiresistive gas sensor with the 2D PANI film, demonstrating stable room-temperature detection of ammonia down to 10 ppt in ambient air with an impressive 10% response. This achievement represents the highest sensitivity among sensors of this kind while maintaining excellent selectivity and repeatability. Moreover, the QLL-controlled polymerization strategy offers an alternative route for precise control of the polymerization process for conducting polymers, enabling the creation of advanced materials with enhanced properties.

Photothermal Conversion of the Oleophilic PVDF/Ti3C2Tx Porous Foam Enables Non-Aqueous Liquid System Applicable Actuator.

Various physical and chemical reaction processes occur in non-aqueous liquid systems, particularly in oil phase systems. Therefore, achieving efficient, accurate, controllable, and cost-effective movement and transfer of substances in the oil phase is crucial. Liquid-phase photothermal actuators (LPAs) are commonly used for material transport in liquid-phase systems due to their remote operability and precise control. However, existing LPAs typically rely on materials like hydrogels and flexible polymers, commonly unsuitable for non-aqueous liquids. Herein, a 3D porous poly(vinylidene fluoride) (PVDF)/Ti3C2Tx actuator is developed using a solvent displacement method. It demonstrates directional movement and controlled material transport in non-aqueous liquid systems. When subject to infrared light irradiation (2.0 W cm-2), the actuator achieves motion velocities of 7.3 and 6 mm s-1 vertically and horizontally, respectively. The actuator's controllable motion capability is primarily attributed to the foam's oil-wettable properties, 3D porous oil transport network, and the excellent photothermal conversion performance of Ti3C2Tx, facilitating thermal diffusion and the Marangoni effect. Apart from multidimensional directions, the actuator enables material delivery and obstacle avoidance by transporting and releasing target objects to a predetermined position. Hence, the developed controllable actuator offers a viable solution for effective motion control and material handling in non-aqueous liquid environments.

Detection of Various Microplastics in Patients Undergoing Cardiac Surgery.

Microplastics have been detected in human stool, lungs, and placentas, which have direct exposure to the external environment through various body cavities, including the oral/anal cavity and uterine/vaginal cavity. Crucial data on microplastic exposure in completely enclosed human organs are still lacking. Herein, we used a laser direct infrared chemical imaging system and scanning electron microscopy to investigate whether microplastics exist in the human heart and its surrounding tissues. Microplastic specimens were collected from 15 cardiac surgery patients, including 6 pericardia, 6 epicardial adipose tissues, 11 pericardial adipose tissues, 3 myocardia, 5 left atrial appendages, and 7 pairs of pre- and postoperative venous blood samples. Microplastics were not universally present in all tissue samples, but nine types were found across five types of tissue with the largest measuring 469 µm in diameter. Nine types of microplastics were also detected in pre- and postoperative blood samples with a maximum diameter of 184 µm, and the type and diameter distribution of microplastics in the blood showed alterations following the surgical procedure. Moreover, the presence of poly(methyl methacrylate) in the left atrial appendage, epicardial adipose tissue, and pericardial adipose tissue cannot be attributed to accidental exposure during surgery, providing direct evidence of microplastics in patients undergoing cardiac surgery. Further research is needed to examine the impact of surgery on microplastic introduction and the potential effects of microplastics in internal organs on human health.

Coaxial Graphene/MXene Microfibers with Interfacial Buffer-Based Lightweight Distance Sensors Assisting Lossless Grasping of Fragile and Deformable Objects.

Lossless and efficient robotic grasping is becoming increasingly important with the widespread application of intelligent robotics in warehouse transportation, human healthcare, and domestic services. However, current sensors for feedback of grasping behavior are greatly restricted by high manufacturing cost, large volume and mass, complex circuit, and signal crosstalk. To solve these problems, here, we prepare lightweight distance sensor-based reduced graphene oxide (rGO)/MXene-rGO coaxial microfibers with interface buffer to assist lossless grasping of a robotic manipulator. The as-fabricated distance microsensor exhibits a high sensitivity of 91.2 m-1 in the distance range of 50-300 µm, a fast response time of 116 ms, a high resolution of 5 µm, and good stability in 500 cycles. Furthermore, the high-performance and lightweight microsensor is installed on the robotic manipulator to reflect the grasp state by the displacement imposed on the sensor. By establishing the correlation between the microsensing signal and the grasp state, the safe, non-destructive, and effective grasp and release of the target can be achieved. The lightweight and high-powered distance sensor displays great application prospects in intelligent fetching, medical surgery, multi-spindle automatic machines, and cultural relics excavation.

In situ characterisation for nanoscale structure-performance studies in electrocatalysis.

Recently, electrocatalytic reactions involving oxygen, nitrogen, water, and carbon dioxide have been developed to substitute conventional chemical processes, with the aim of producing clean energy, fuels and chemicals. A deepened understanding of catalyst structures, active sites and reaction mechanisms plays a critical role in improving the performance of these reactions. To this end, in situ/operando characterisations can be used to visualise the dynamic evolution of nanoscale materials and reaction intermediates under electrolysis conditions, thus enhancing our understanding of heterogeneous electrocatalytic reactions. In this review, we summarise the state-of-the-art in situ characterisation techniques used in electrocatalysis. We categorise them into three sections based on different working principles: microscopy, spectroscopy, and other characterisation techniques. The capacities and limits of the in situ characterisation techniques are discussed in each section to highlight the present-day horizons and guide further advances in the field, primarily aiming at the users of these techniques. Finally, we look at challenges and possible strategies for further development of in situ techniques.

Metal Halides for High-Capacity Energy Storage.

High-capacity electrochemical energy storage systems are more urgently needed than ever before with the rapid development of electric vehicles and the smart grid. The most efficient way to increase capacity is to develop electrode materials with low molecular weights. The low-cost metal halides are theoretically ideal cathode materials due to their advantages of high capacity and redox potential. However, their cubic structure and large energy barrier for deionization impede their rechargeability. Here, the reversibility of potassium halides, lithium halides, sodium halides, and zinc halides is achieved through decreasing their dimensionality by the strong π-cation interactions between metal cations and reduced graphene oxide (rGO). Especially, the energy densities of KI-, KBr-, and KCl-based materials are 722.2, 635.0, and 739.4 Wh kg-1 , respectively, which are higher than those of other cathode materials for potassium-ion batteries. In addition, the full-cell with 2D KI/rGO as cathode and graphite as anode demonstrates a lifespan of over 150 cycles with a considerable capacity retention of 57.5%. The metal halides-based electrode materials possess promising application prospects and are worthy of more in-depth researches.

A Novel Ionic Conductive Polyurethane Based on Deep Eutectic Solvent Continuing Traditional Merits.

Artificial intelligence (AI) has become increasingly popular along with the development of the bionic neural system. Ionic conductors play an important role in the AI system due to the ability of bionic sensing and signal transporting. Traditional low-polarity elastomers possess outstanding mechanical strength and stability, such as polyurethane, which is difficult to be directly endowed with ionic conductivity without impairing its properties. Herein, we have first put forward a new approach to synthesize a liquid-free ionic conductive polyurethane (CPU) through one-step copolymerization between a green deep eutectic solvent (DES) and a prepolymer of polyurethane. The as-prepared CPU can retain the native properties of the traditional polyurethane (PU) such as the homogeneous phase, ease of molding, high transparency (about 93.3%), and excellent mechanical properties. By introducing the DES as the covalent cross-linking agent and ionic conductor at the same time, the CPU also has fine ionic conductivity (3.78 × 10-5 S cm-1), environmental resistance like anti-freezing (-20 °C), and solvent resistance. Based on the excellent conductivity and mechanical strength, the flexible CPU can be applied as a sensing element in pressure sensors. The CPU-based sensor has presented long-term stability, high sensitivity, and wide-ranging response (0.17-3.28 MPa) to the applied pressure, which will be suitable for the industrial demands for practical applications.

Integrated Polypyrrole-Based Smart Clothing with Photothermal Conversion and Thermosensing Functions for Wearable Applications.

Integrated smart clothing with photothermal conversion and thermosensing functions is highly desired for next-generation smart wearable applications. Conducting polymer is a promising material that possesses efficient photothermal conversion performance, great sensitivity to temperature change, and excellent processing properties. In this study, we report a new wearable material using the conducting polymer polypyrrole (PPy) as a photothermal and thermosensing layer and nonwoven fabric as flexible textiles to fabricate integrated PPy-based smart clothing (IPSC). The surface temperature of the prepared IPSC can be as high as 68.4 °C with 808 nm near-infrared (NIR) irradiation at a power destiny of 1 kW/m2. Meanwhile, a temperature resolution of 1 °C can be achieved for IPSC. These superiorities are in favor of fabricating multifunctional smart wearables to satisfy the needs in future life.

Anion Concentration Gradient-Assisted Construction of a Solid-Electrolyte Interphase for a Stable Zinc Metal Anode at High Rates.

Coulombic efficiency (CE) and cycle life of metal anodes (lithium, sodium, zinc) are limited by dendritic growth and side reactions in rechargeable metal batteries. Here, we proposed a concept for constructing an anion concentration gradient (ACG)-assisted solid-electrolyte interphase (SEI) for ultrahigh ionic conductivity on metal anodes, in which the SEI layer is fabricated through an in situ chemical reaction of the sulfonic acid polymer and zinc (Zn) metal. Owing to the driving force of the sulfonate concentration gradient and high bulky sulfonate concentration, a promoted Zn2+ ionic conductivity and inhibited anion diffusion in the SEI layer are realized, resulting in a significant suppression of dendrite growth and side reaction. The presence of ACG-SEI on the Zn metal enables stable Zn plating/stripping over 2000 h at a high current density of 20 mA cm-2 and a capacity of 5 mAh cm-2 in Zn/Zn symmetric cells, and moreover an improved cycling stability is also observed in Zn/MnO2 full cells and Zn/AC supercapacitors. The SEI layer containing anion concentration gradients for stable cycling of a metal anode sheds a new light on the fundamental understanding of cation plating/stripping on metal electrodes and technical advances of rechargeable metal batteries with remarkable performance under practical conditions.

In Situ Construction of a Multifunctional Quasi-Gel Layer for Long-Life Aqueous Zinc Metal Anodes.

Aqueous zinc (Zn)-ion batteries are considered very promising in grid-scale energy storage systems. However, the dendrite, corrosion, and H2 evolution issues of Zn anode have restricted their further applications. Herein, to solve these issues, a hydrophilic layer, consisting of a covalent organic polymer (COP) and carboxylmethyl cellulose (CMC), is designed to in situ construct a multifunctional quasi-gel (COP-CMC/QG) interface between Zn metal and the electrolyte. The COP-CMC/QG interface can significantly improve the rechargeability of the Zn anode through enhancing Zn2+ transport kinetics, guiding uniform nucleation, and suppressing Zn corrosion and H2 evolution. As a result, the COP-CMC-Zn anode exhibits a reduced overpotential (12 mV at 0.25 mA cm-2), prolonged cycle life (over 4000 h at 0.25 mA cm-2 and 2000 h at 5 mA cm-2 in symmetrical cells), and elevated full-cell (Zn/MnO2) performance. This work provides an efficient approach to achieve long-life Zn metal anodes and paves the way toward high-performance Zn-based and other metal-ion batteries.

Reduced Graphene Oxide-Polypyrrole Aerogel-Based Coaxial Heterogeneous Microfiber Enables Ultrasensitive Pressure Monitoring of Living Organisms.

Pressure sensors for living organisms can monitor both the movement behavior of the organism and pressure changes of the organ, and they have vast perspectives for the health management information platform and disease diagnostics/treatment through the micropressure changes of organs. Although pressure sensors have been widely integrated with e-skin or other wearable systems for health monitoring, they have not been approved for comprehensive surveillance and monitoring of living organisms due to their unsatisfied sensing performance. To solve the problem, here, we introduce a novel structural design strategy to manufacture reduced graphene oxide-polypyrrole aerogel-based microfibers with a typical coaxial heterogeneous structure, which significantly enhances the sensitivity, resolution, and stability of the derived pressure microsensors. The as-fabricated pressure microsensors exhibit ultrahigh sensitivities of 12.84, 18.27, and 4.46 kPa-1 in the pressure ranges of 0-20, 20-40, and 40-65 Pa, respectively, high resolution (0.2 Pa), and good stability in 450 cycles. Furthermore, the microsensor is applied to detect the movement behavior and organic micropressure changes for mice and serves as a platform for monitoring micropressure for the integrative diagnosis both in vivo and in vitro of organisms.

Highly Efficient Photothermal Conversion of Ti3C2Tx/Ionic Liquid Gel Pen Ink for Smoothly Writing Ultrasensitive, Wide-Range Detecting, and Flexible Thermal Sensors.

Photothermal conversion behavior has a vital application to disease therapy, water purification, or uncontacted heaters. The fabrication of high-performance photothermal conversion materials especially for near-infrared (NIR) light and microstructures has attracted a great deal of attention. Among numerous substances, MXene as a new type of 2D material with semi-metallic and unique electromagnetic properties presents a broader absorption of light and even a typical plasmonic absorption near the NIR-I area (808 nm), which has made it suitable for photothermal conversion. Here, we propose a facile approach for preparing a Ti3C2Tx/ionic liquid ink with a high photothermal conversion efficiency. The as-prepared ink has showed good wettability of various substrates as well as the high sensitivity of 808 nm NIR light irradiation and a wide range of thermal variation. After packing the ink into a gel pen refill, the flexible thermal chips could be easily obtained just by pen writing on the soft surface with the designed size, which also have become an optimal candidate for the thermal alarm system.

A hybrid superconcentrated electrolyte enables 2.5 V carbon-based supercapacitors.

A hybrid solvent in salt electrolyte was developed by hybridizing aqueous and organic solvents in concentrated lithium bis(fluorosulfonyl)imide (LiFSI) salts, such an electrolyte provides an unprecedented electrochemical window of 5.35 V, which is even comparable to traditional organic electrolytes, and enables a super-stable carbon-based symmetric supercapacitor with a long life of 10 000 cycles at an operating voltage of 2.5 V.

A Universal Approach to Aqueous Energy Storage via Ultralow-Cost Electrolyte with Super-Concentrated Sugar as Hydrogen-Bond-Regulated Solute.

Aqueous energy-storage systems have attracted wide attention due to their advantages such as high security, low cost, and environmental friendliness. However, the specific chemical properties of water induce the problems of narrow electrochemical stability window, low stability of water-electrode interface reactions, and dissolution of electrode materials and intermediate products. Therefore, new low-cost aqueous electrolytes with different water chemistry are required. The nature of water depends largely on its hydroxyl-based hydrogen bonding structure. Therefore, the super-concentrated hydroxyl-rich sugar solutions are designed to change the original hydrogen bonding structure of water. The super-concentrated sugars can reduce the free water molecules and destroy the tetrahedral structure, thus lowering the binding degree of water molecules by breaking the hydrogen bonds. The ionic electrolytes based on super-concentrated sugars have the expanded electrochemical stability window (up to 2.812 V), wide temperature adaptability (-50 to 80 °C), and fair ionic conductivity (8.536 mS cm-1 ). Aqueous lithium-, sodium-, potassium-ion batteries and supercapacitors using super-concentrated sugar-based electrolytes demonstrate an excellent electrochemical performance. The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry.

Highly Selective Wearable Smartsensors for Vapor/Liquid Amphibious Methanol Monitoring.

A wearable screen-printed electrochemical smartsensor with excellent selectivity for methanol quantification has been developed. This smartsensor consists of a printable sensing system modified with platinum (Pt) confined in a reduced graphene oxide (rGO) matrix, as well as a compact electronic interface for data collection. The real-time electrochemical signal from methanol could be remotely detected and transmitted to a smartphone by blue tooth. It performs good environmental adaptability of vapor/liquid amphibious behaviors. Owing to the uniform distribution of Pt loading on the rGO nanosheets, this sensor demonstrates high selectivity, sensitivity, stability, and recoverability both in vapor and liquid during temperature or humidity diversification, compared with other resistance-based sensors. It also achieves good bending and stretching performance, and it could be a possible candidate device for the quantification of methanol in different environments.

Single crystal growth and ferromagnetism of Cr-doped Sb4Te3.

Here we report the single crystal growth, magnetic and transport properties of Cr-doped Sb4Te3, (Sb1-x Cr x )4Te3, with doping concentrations x = 0.25%, 0.5%, 0.75%, and 1%. The samples with lower doping concentrations are paramagnetic, while ferromagnetism appears in higher doped samples with the highest Curie temperature of 7 K when x = 1%. Anomalous Hall effect with clear hysteresis loop is observed in the samples with x = 1%, indicating the intrinsic ferromagnetism in the system. Hall resistivity measurements show the dominant charge carriers are holes and the density of holes increases with the doping concentration. This work provides a possible single-crystalline platform for further experimental researches on the nontrivial band topology in Sb4Te3, and enriches the ferromagnetic members in the transition metal doped (Sb2) m -Sb2Te3 topological material series.

Enhanced Ion Conduction via Epitaxially Polymerized Two-Dimensional Conducting Polymer for High-Performance Cathode in Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are one of the promising choices for the future large-scale grid energy storage, in which Mn-based cathode materials have the advantages of low cost and environmental friendliness. However, their capacity delivery and cycling stability are limited by the large bulk-induced incomplete zincation and structure pulverization. Here, we develop a strategy of epitaxial polymerization in the liquid phase to fabricate two-dimensional (2D) MnOx/polypyrrole nanosheets to enhance the zinc-ion storage by realizing the efficient utilization of active materials and improving the structural stability via a polymerized framework. An ultrahigh capacity of 408 mAh g-1 is demonstrated at 1C rate, and an excellent capacity retention of 78% is realized after 2800 cycles at 5C rate for the AZIB. Electrochemical and morphological characterizations reveal that the unique 2D structure contributes to both the electron/ion conductivity and structural stability. The epitaxial polymerization of the conducting polymer in the liquid phase provides a new perspective to the synthesis of high-performance electrode materials and 2D conducting polymers.

A graphene-based smart thermal conductive system regulated by a reversible pressure-induced mechanism.

Thermal dissipation and thermal insulation are important for maintaining the normal operation of devices, extending the service life of instruments, ensuring efficient energy utilization, and improving temperature-related human comfort. Yet it is difficult to achieve both the functions of thermal dissipation and thermal insulation in a single material with a specific thermal conductivity under specific conditions. In this work, based on the huge difference in thermal conductivity between air and reduced graphene oxide (rGO), a pressure-induced mechanism is used to regulate the amount of air inside an rGO foam, so that a periodic reversible change of thermal conductivity can be realized, achieving the dual functions of thermal dissipation and thermal insulation to meet the requirements of different application scenarios. Further fitting calculations suggest that the thermal conductivity of rGO foam is positively and negatively associated with the applied pressure and temperature, respectively, and it can be calculated for given pressure and temperature conditions. The pressure-induced reversible regulation of thermal conductivity in rGO foam provides a new design construct for smart thermal-management devices, and a new direction of application for 2D materials.

Facile Wearable Vapor/Liquid Amphibious Methanol Sensor.

Detection of methanol is a significant segment for body health and work safety in the production of chemical industry. However, there hardly exists highly selective methanol detection system with green environment for vapor or liquid adaptability, as well as large linear relationship. A facile wearable vapor/liquid amphibious electrochemical sensor for monitoring methanol has been carried out for the first time in this Article. This wearable methanol sensor was fabricated by using a simple screen-printing technology for accomplishing a microdevice platform, showing good linear relationship, high selectivity (multiple volatile chemical compounds), reliable repeatability, good stability, and excellent stretching and bending performance (nitrile glove-based sensor) without pretreatment or adding any polymers into inks. Owing to its good environmental adaptability of vapor or liquid and various sensing behaviors (high sensitivity and wide linear range) by being modified with different content of platinum catalyst, this methanol sensor would have tremendous potential application for environmental monitoring on smart wearable devices when employed based on various platforms (such as PET, cotton, and nitrile gloves).

Highly Sensitive Wearable Pressure Sensors Based on Three-Scale Nested Wrinkling Microstructures of Polypyrrole Films.

Pressure sensors have a variety of applications including wearable devices and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, and a low-cost preparation are extremely needed. Herein, we fabricate highly sensitive pressure sensors based on hierarchically patterned polypyrrole (PPy) films, which are composed of three-scale nested surface wrinkling microstructures through a simple process. Namely, double-scale nested wrinkles are generated via in situ self-wrinkling during oxidative polymerization growth of PPy film on an elastic poly(dimethylsiloxane) substrate in the mixed acidic solution. Subsequent heating/cooling processing induces the third surface wrinkling and thus the controlled formation of three-scale nested wrinkling microstructures. The multiscale nested microstructures combined with stimulus-responsive characteristic and self-adaptive ability of wrinkling morphologies in PPy films offer the as-fabricated piezoresistive pressure sensors with a high sensitivity (19.32 kPa-1), a low detection limit (1 Pa), an ultrafast response (20 ms), and excellent durability and stability (more than 1000 circles), these comprehensive sensing properties being higher than the reported results in literature. Moreover, the pressure sensors have been successfully applied in the wearable electronic fields (e.g., pulse detection and voice recognition) and microcircuit controlling, as demonstrated here.