Stretchable, Electrochemically-Stable Electrochromic Devices Based on Semi-Embedded Ag@Au Nanowire Network.

Stretchable electrochromic (EC) devices that can adapt the irregular and dynamic human surfaces show promising applications in wearable display, adaptive camouflage, and visual sensation. However, challenges exist in lacking transparent conductive electrodes with both tensile and electrochemical stability to assemble the complex device structure and endure harsh electrochemical redox reactions. Herein, a wrinkled, semi-embedded Ag@Au nanowire (NW) networks are constructed on elastomer substrates to fabricate stretchable, electrochemically-stable conductive electrodes. The stretchable EC devices are then fabricated by sandwiching a viologen-based gel electrolyte between two conductive electrodes with the semi-embedded Ag@Au NW network. Because the inert Au layer inhibits the oxidation of Ag NWs, the EC device exhibits much more stable color changes between yellow and green than those with pure Ag NW networks. In addition, since the wrinkled semi-embedded structure is deformable and reversibly stretched without serious fractures, the EC devices still maintain excellent color-changing stability under 40% stretching/releasing cycles.

Synergistic Interaction of Dual-Polymer Networks Containing Viologens-Anchored Poly(ionic liquid)s Enabling Long-Life and Large-Area Electrochromic Organogels.

Viologens-based electrochromic (EC) devices with multiple color changes, rapid response time, and simple all-in-one architecture have aroused much attention, yet suffer from poor redox stability caused by the irreversible aggregation of free radical viologens. Herein, the semi-interpenetrating dual-polymer network (DPN) organogels are introduced to improve the cycling stability of viologens-based EC devices. The primary cross-linked poly(ionic liquid)s (PILs) covalently anchored with viologens can suppress irreversible face-to-face contact between radical viologens. The secondary poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) chains with strong polar groups of -F can not only synergistically confine the viologens by the strong electrostatic effect, but also improve the mechanical performance of the organogels. Consequently, the DPN organogels show excellent cycling stability (87.5% retention after 10 000 cycles) and mechanical flexibility (strength of 3.67 MPa and elongation of 280%). Three types of alkenyl viologens are designed to obtain blue, green, and magenta colors, demonstrating the universality of the DPN strategy. Large-area EC devices (20 × 30 cm) and EC fibers based on organogels are assembled to demonstrate promising applications in green and energy-saving buildings and wearable electronics.

Electron-level insight into efficient synergistic oxygen evolution catalysis at multimetallic sites in PtNiFeCoCu high-entropy alloys.

The exploration of high-quality and efficient electrocatalysts is crucial for the advancement of clean energy utilization and the development of energy conversion technologies. Recently, high-entropy alloys (HEA) have been actively explored as viable catalysts for water electrolysis due to their unique performance such as wide scope for compositional adjustments, excellent catalytic activity, and outstanding stability. However, the mechanism of synergistic oxygen evolution by HEA electrocatalysts at multiple sites has not been systematically and clearly demystified. Herein, in this paper, Pt is combined with inexpensive metals Ni, Cu, Fe, and Co to form a stable HEA structure. The synergistic catalytic mechanism of the PtNiFeCoCu HEA in the oxygen evolution reaction (OER) has been investigated, and the structure has been demonstrated to exhibit excellent hydrogen evolution reaction (HER) activity. The results suggest that the PtNiFeCoCu HEA catalyst achieved a lower overpotential of 0.44 V in the acidic OER, demonstrating that the PtNiFeCoCu HEA is a bifunctional electrocatalyst. In addition, oxygen intermediates are synergistically adsorbed on the surface of high-entropy alloys through multimetallic sites, which breaks the limitation of limited active sites. Further calculations indicated that the favorable OER activity of the catalyst originated from the strong associative coupling of the d orbitals of the synergistic metal sites to the 2p orbitals of the oxygen intermediates with enhanced synergistic effects. This work further elucidates the multisite synergistic catalysis of the PtNiFeCoCu HEA, providing a unique perspective to uncover the source of the high catalytic performance of HEA electrocatalysts.

Insight into the Fe atom-FeS cluster synergistic catalysis mechanism for the oxygen evolution reaction in NiS2-based electrocatalysts.

The development of highly active oxygen evolution reaction (OER) catalysts with fast kinetics is crucial for the advancement of clean energy and fuel conversion to achieve a sustainable energy future. Recently, the synergistic effect of single-atom doping and multicomponent clusters has been demonstrated to significantly improve the catalytic activity of materials. However, such synergistic effects involving multi-electron and proton transfer processes are quite complex and many crucial mechanistic details need be well comprehended. We ingeniously propose a catalyst, (Fed-FeSc)@NiS2 (d stands for doping and c stands for clustering), with Fe and FeS acting synergistically on a NiS2 substrate. Specifically, fully dynamic monitoring of multiple active sites at the (Fed-FeSc)@NiS2 interface using metadynamics is innovatively performed. The results show that the rate determining step value at the overpotential of 1.23 V for the synergistic (Fed-FeSc)@NiS2 is 1.55 V, decreased by 6.67% and 35.29% compared to those of the independently acting single-atom doping and multi-clusters. The unique synergistic structure dramatically increases the d-band centre of the Fe site (-1.45 eV), endowing (Fed-FeSc)@NiS2 with more activity than conventional commercial Ir-C catalysts. This study provides insights into the synergistic effects of single-atom doping and multi-component clusters, leading to exploratory inspiration for the design of highly efficient OER catalysts.

Thermal and electrical transport properties of two-dimensional Dirac graphenylene: a first-principles study.

The development of high performance two-dimensional thermoelectric (TE) materials is crucial for enhancing the conversion of waste heat into electricity and for achieving the transition to new energy. In recent years, two-dimensional Dirac materials with high carrier mobility and non-trivial topological properties have been expected to extend the application of carbon-based materials in the TE field. However, research on the TE properties of two-dimensional Dirac materials is still scarce, and the relevant physical mechanisms that affect the TE figure of merit of the materials are still unclear. Therefore, we carefully selected a typical and experimentally synthesized Dirac structure, graphenylene, and systematically studied its thermal transport and electrical transport properties using density functional theory (DFT) and Boltzmann transport theory. The results show that the ZT value of graphenylene exhibits an extremely significant anisotropy. There is a significant discrepancy in the figure of merit (ZT) values of n-type and p-type systems at the optimum doping concentration, i.e., the ZT value of the n-type system (0.49) is one order of magnitude greater than that of the p-type system (0.06). Graphenylene exhibits excellent electronic performance due to its unique electronic band structure and has an extremely high conductivity (for the n-type system, electrical conductivity at room temperature is 109 S m-1). Interestingly, graphenylene has an unusually higher ZT at low temperature (0.5 at 300 K) than at high temperature (0.3 at 800 K) for n-type doping along the x-axis, contrary to the conventional view that higher ZT values exist in the high temperature range. This work provides a deep insight into the TE properties of two-dimensional Dirac carbon materials and offers new perspectives for enhancing the TE performance and application of carbon-based nanomaterials.

New insights into phase transition behavior and electrochemistry corrosion of three-dimensional biphenylene.

It is estimated that the annual cost of corrosion in most countries accounts for 3-4% of gross domestic product, far exceeding the losses caused by natural disasters, prompting scientists to continuously search for high-performance anti-corrosion materials. Among these high-performance materials, two-dimensional carbon materials represented by graphene have received widespread attention due to their excellent chemical stability and anti-permeability. However, some studies have found that the poor ability of graphene to bind to the interface and the electrical coupling caused by metallicity make it possible to protect copper from corrosion only for a short period of time. To circumvent these issues, through phase behavior research, interface binding property simulation and corrosion mechanism exploration, we propose a more promising anti-corrosive three-dimensional (3D) biphenylene diamond-like carbon membrane (BP-DLC). The kinetic study results show that due to the Gibbs free energy of biphenylene structures below three layers being lower than 0, few-layer biphenylene can spontaneously generate phase transitions of limited size, forming a biphenylene diamond-like membrane and exhibiting superior mechanical properties and a certain degree of flexibility. Mechanical and electronic performance results further show that there is a strong bonding effect between BP-DLC and the metal surface, which further enhances the bistate heterostructure and prolongs the coating life of BP-DLC materials. Compared with pure graphene and Cu substrates, BP-DLC membranes exhibit stronger corrosion resistance by reducing porosity, increasing charge transfer and hindering the diffusion of corrosion ions to the substrate. This study provides a new strategy for constructing corrosion-resistant materials by designing long-term stable and highly corrosion-resistant diamond-like membranes.

Electrochemical Actuators with Multicolor Changes and Multidirectional Actuation.

Electrochemical (EC) actuators have garnered significant attention in recent years, yet there are still some critical challenges to limit their application range, such as responsive time, multifunctionality, and actuating direction. Herein, an EC actuator with a back-to-back structure is fabricated by stacking two membranes with bilayer V2 O5 nanowires/single-walled carbon nanotubes (V2 O5 NWs/SWCNTs) networks, and shows a synchronous high actuation amplitude (about ±9.7 mm, ±28.4°) and multiple color changes. In this back-to-back structure, the inactive SWCNTs layer is used as a conductive current collector, and the bilayer network is attached to a porous polymer membrane. The dual-responsive processes of V2 O5 nanowires (V2 O5 NWs) actuation films and actuators are also deeply investigated through in situ EC X-ray diffraction and Raman spectroscopy. The results show that the EC actuation of the V2 O5 NWs/SWCNTs film is highly related to the redox behavior of the pseudocapacitive V2 O5 NWs layer. At last, both V2 O5 NWs and W18 O49 nanowires (W18 O49 NWs)-based EC actuators are constructed to demonstrate the multicolor changes and multidirectional actuation induced by the opposite lattice changes of V2 O5 NWs and W18 O49 NWs during ionic de-/intercalation, guiding the design of multifunctional EC actuators in the future.

Ultrathin, Washable, and Large-Area Graphene Papers for Personal Thermal Management.

Freestanding, flexible/foldable, and wearable bifuctional ultrathin graphene paper for heating and cooling is fabricated as an active material in personal thermal management (PTM). The promising electrical conductivity grants the superior Joule heating for extra warmth of 42 °C using a low supply voltage around 3.2 V. Besides, based on its high out-of-plane thermal conductivity, the graphene paper provides passive cooling via thermal transmission from the human body to the environment within 7 s. The cooling effect of graphene paper is superior compared with that of the normal cotton fiber, and this advantage will become more prominent with the increased thickness difference. The present bifunctional graphene paper possesses high durability against bending cycles over 500 times and wash time over 1500 min, suggesting its great potential in wearable PTM.

High Thermoelectric Performance in Ti3C2Tx MXene/Sb2Te3 Composite Film for Highly Flexible Thermoelectric Devices.

Flexible thin-film thermoelectric devices (TEDs) can generate electricity from the heat emitted by the human body, which holds great promise for use in energy supply and biomonitoring technologies. The p-type Sb2Te3 hexagon nanosheets are prepared by the hydrothermal synthesis method and compounded with Ti3C2Tx to make composite films, and the results show that the Ti3C2Tx content has a significant impact on the thermoelectric properties of the composite films. When the Ti3C2Tx content is 2 wt%, the power factor of the composite film reaches ≈59 µW m-1 K-2. Due to the outstanding electrical conductivity, high specific surface area, and excellent flexibility of Ti3C2Tx, the composite films also exhibit excellent thermoelectric and mechanical properties. Moreover, the small addition of Ti3C2Tx has a negligible effect on the phase composition of Sb2Te3 films. The TED consists of seven legs with an output voltage of 45 mV at ΔT = 30 K. The potential of highly flexible thin film TEDs for wearable energy collecting and sensing is great.

Dual-Function Wearable Hydrogel Optical Fiber for Monitoring Posture and Sweat pH.

In recent years, wearable devices have been widely used for human health monitoring. Such monitoring predominantly relies on the principles of optics and electronics. However, electronic detection is susceptible to electromagnetic interference, and traditional optical fiber detection is limited in functionality and unable to simultaneously detect both physical and chemical signals. Hence, a wearable, embedded asymmetric color-blocked optical fiber sensor based on a hydrogel has been developed. Its sensing principle is grounded in the total internal reflection within the optical fiber. The method for posture sensing involves changes in the light path due to fiber bending with color blocks providing wavelength-selective modulation by absorption changes. Sweat pH sensing is facilitated by variations in fluorescence intensity triggered by sweat-induced conformational changes in Rhodamine B. With just one fiber, it achieves both physical and chemical signal detection. Fabricated using a molding technique, this fiber boasts excellent biocompatibility and can accurately discern single and multiple bending points, with a recognition range of 0-90° for a single segment, a detection limit of 0.02 mm-1 and a sweat pH sensing linear regression R2 of 0.993, alongside great light propagation properties (-0.6 dB·cm-1). With its extensive capabilities, it holds promise for applications in medical monitoring.

Air-Working Electrochromic Artificial Muscles.

Artificial muscles are indispensable components for next-generation robotics to mimic the sophisticated movements of living systems and provide higher output energies when compared with real muscles. However, artificial muscles actuated by electrochemical ion injection have problems with single actuation properties and difficulties in stable operation in air. Here, air-working electrochromic artificial muscles (EAMs) with both color-changing and actuation functions are reported, which are constructed based on vanadium pentoxide nanowires and carbon tube yarn. Each EAM can generate a contractile stroke of ≈12% during stable operation in the air with multiple color changes (yellow-green-gray) under ±4 V actuation voltages. The reflectance contrast is as high as 51%, demonstrating the excellent versatility of the EAMs. In addition, a torroidal EAM arrangement with fast response and high resilience is constructed. The EAM's contractile stroke can be displayed through visual color changes, which provides new ideas for future artificial muscle applications in soft robots and artificial limbs.

Hyperstable Eutectic Core-Spun Fiber Enabled Wearable Energy Harvesting and Personal Thermal Management Fabric.

Electronic textiles have gradually evolved into one of the most important mainstays of flexible electronics owing to their good wearability. However, textile multifunctionality is generally achieved by stacking functional modules, which is not conducive to wearability. Integrating these modules into a single fiber provides a better solution. In this work, a core-spun functional fiber (CSF) constructed from hyper-environmentally stable Zn-based eutectogel as the core layer and polytetrafluoroethylene as the sheath is designed. The CSF achieves a synergistic output effect of piezoelectricity-enhanced triboelectricity, as well as reliable hydrophobicity, and high mid-infrared emissivity and visible light reflectivity. A monolayer functionalized integrated textile is woven from the CSF to enable effective energy (mechanical and droplet energy) harvesting and personal thermal management functions. Furthermore, scenarios for the energy supply, motion detection, and outdoor use of electronic fabrics for electronics applications are demonstrated, opening new avenues for the functional integration of electronic textiles.

An afferent nerve-like electronic device with somatic mechanical perception and sensation management.

Tactile and pain perception are essential for biological skin to interact with the external environment. This complex interplay of sensations allows for the detection of potential threats and appropriate responses to stimuli. However, the challenge is to enable flexible electronics to respond to mechanical stimuli such as biological skin, and researchers have not clearly reported the successful integration of somatic mechanical perception and sensation management functions into neuro-like electronics. In this work, an afferent nerve-like device with a pressure sensor and a perception management module is proposed. The pressure sensor comprises two conductive fabric layers and an ionic hydrogel, forming a capacitor structure that emulates the swift transition from tactile to pain perception under mechanical stimulation. Drawing inspiration from the neuronal "gate control" mechanism, the sensation management module adjusts signals in response to rubbing, accelerating the discharge process and reducing the perception duration, thereby replicating the inhibitory effect of biological neurons on pain following tactile interference. This integrated device, encompassing somatic mechanical perception and sensation management, holds promise for applications in soft robotics, prosthetics, and human-machine interaction.

CoFe hydroxide towards CoP2-FeP4 heterojunction for efficient and long-term stable water oxidation.

Electrochemical water splitting stands out as a promising avenue for green hydrogen production, yet its efficiency is fundamentally governed by the oxygen evolution reaction (OER). In this work, we investigated the growth mechanism of CoFe hydroxide formed by in situ self-corrosion of iron foam for the first time and the significant influence of dissolved oxygen in the immersion solution on this process. Based on this, the CoP2-FeP4/IF heterostructure catalytic electrode demonstrates exceptional OER activity in a 1 M KOH electrolyte, with an overpotential of only 253 ± 4 mV (@10 mA cm-2), along with durability exceeding 1000 h. Density functional theory calculations indicate that constructing heterojunction interfaces promotes the redistribution of interface electrons, optimizing the free energy of adsorbed intermediate during the water oxidation process. This research highlights the importance of integrating self-corroding in-situ growth with interface engineering techniques to develop efficient water splitting materials.

Electrochemical sensing fibers for wearable health monitoring devices.

Real-time monitoring of health conditions is an emerging strong issue in health care, internet information, and other strongly evolving areas. Wearable electronics are versatile platforms for non-invasive sensing. Among a variety of wearable device principles, fiber electronics represent cutting-edge development of flexible electronics. Enabled by electrochemical sensing, fiber electronics have found a wide range of applications, providing new opportunities for real-time monitoring of health conditions by daily wearing, and electrochemical fiber sensors as explored in the present report are a promising emerging field. In consideration of the key challenges and corresponding solutions for electrochemical sensing fibers, we offer here a timely and comprehensive review. We discuss the principles and advantages of electrochemical sensing fibers and fabrics. Our review also highlights the importance of electrochemical sensing fibers in the fabrication of "smart" fabric designs, focusing on strategies to address key issues in fiber-based electrochemical sensors, and we provide an overview of smart clothing systems and their cutting-edge applications in therapeutic care. Our report offers a comprehensive overview of current developments in electrochemical sensing fibers to researchers in the fields of wearables, flexible electronics, and electrochemical sensing, stimulating forthcoming development of next-generation "smart" fabrics-based electrochemical sensing.

Scale-Bridging Mechanics Transfer Enables Ultrabright Mechanoluminescent Fiber Electronics.

Mechanoluminescent (ML) fibers and textiles enable stress visualization without auxiliary power, showing great potential in wearable electronics, machine vision, and human-computer interaction. However, traditional ML devices suffer from inefficient stress transfer in soft-rigid material systems, leading to low luminescence brightness and short cycle life. Here, we propose a tendon-inspired scale-bridging mechanics transfer mechanism for ML composites, which employs molecular-scale copolymerized cross-linking and nanoscale inorganic nanoparticles as hierarchical stress transfer sites. This strategy effectively reduces the dissipation of stress in molecular chain segments and alleviates local stress concentration, increases luminescence by 9 times, and extends cycle life to more than 10,000 times. Furthermore, a scalable (kilometer-scale) anti-Plateau-Rayleigh instability manufacturing technology is developed for thermoset ML fibers, compatible with various existing textile techniques. We also demonstrate its system-level applications in motion capture, underwater interaction, etc., providing a feasible strategy for the next generation of smart visual textiles.

Topological MXene Network Enabled Mixed Ion-Electron Conductive Hydrogel Bioelectronics.

Mixed ion-electron conductive (MIEC) bioelectronics has emerged as a state-of-the-art type of bioelectronics for bioelectrical signal monitoring. However, existing MIEC bioelectronics is limited by delamination and transmission defects in bioelectrical signals. Herein, a topological MXene network enhanced MIEC hydrogel bioelectronics that simultaneously exhibits both electrical and mechanical property enhancement while maintaining adhesion and biocompatibility, providing an ideal MIEC bioelectronics for electrophysiological signal monitoring, is introduced. Compared with nontopology hydrogel bioelectronics, the MXene topology increases the dynamic stability of bioelectronics by a factor of 8.4 and the electrical signal by a factor of 10.1 and reduces the energy dissipation by a factor of 20.2. Besides, the topology-enhanced hydrogel bioelectronics exhibits low impedance (<25 Ω) at physiologically relevant frequencies and negligible impedance fluctuation after 5000 stretch cycles. The creation of multichannel bioelectronics with high-fidelity muscle action mapping and gait recognition was made possible by achieving such performance.

Phyto-inspired sustainable and high-performance fabric generators via moisture absorption-evaporation cycles.

Collecting energy from the ubiquitous water cycle has emerged as a promising technology for power generation. Here, we have developed a sustainable moisture absorption-evaporation cycling fabric (Mac-fabric). On the basis of the cycling unidirectional moisture conduction in the fabric and charge separation induced by the negative charge channel, sustainable constant voltage power generation can be achieved. A single Mac-fabric can achieve a high power output of 0.144 W/m2 (5.76 × 102 W/m3) at 40% relative humidity (RH) and 20°C. By assembling 500 series and 300 parallel units of Mac-fabrics, a large-scale demo achieves 350 V of series voltage and 33.76 mA of parallel current at 25% RH and 20°C. Thousands of Mac-fabric units are sewn into a tent to directly power commercial electronic products such as mobile phones in outdoor environments. The lightweight (300 g/m2) and soft characteristics of the Mac-fabric make it ideal for large-area integration and energy collection in real circumstances.

Triboelectric micro-flexure-sensitive fiber electronics.

Developing fiber electronics presents a practical approach for establishing multi-node distributed networks within the human body, particularly concerning triboelectric fibers. However, realizing fiber electronics for monitoring micro-physiological activities remains challenging due to the intrinsic variability and subtle amplitude of physiological signals, which differ among individuals and scenarios. Here, we propose a technical approach based on a dynamic stability model of sheath-core fibers, integrating a micro-flexure-sensitive fiber enabled by nanofiber buckling and an ion conduction mechanism. This scheme enhances the accuracy of the signal transmission process, resulting in improved sensitivity (detectable signal at ultra-low curvature of 0.1 mm-1; flexure factor >21.8% within a bending range of 10°.) and robustness of fiber under micro flexure. In addition, we also developed a scalable manufacturing process and ensured compatibility with modern weaving techniques. By combining precise micro-curvature detection, micro-flexure-sensitive fibers unlock their full potential for various subtle physiological diagnoses, particularly in monitoring fiber upper limb muscle strength for rehabilitation and training.

Single body-coupled fiber enables chipless textile electronics.

Intelligent textiles provide an ideal platform for merging technology into daily routines. However, current textile electronic systems often rely on rigid silicon components, which limits seamless integration, energy efficiency, and comfort. Chipless electronic systems still face digital logic challenges owing to the lack of dynamic energy-switching carriers. We propose a chipless body-coupled energy interaction mechanism for ambient electromagnetic energy harvesting and wireless signal transmission through a single fiber. The fiber itself enables wireless visual-digital interactions without the need for extra chips or batteries on textiles. Because all of the electronic assemblies are merged in a miniature fiber, this facilitates scalable fabrication and compatibility with modern weaving techniques, thereby enabling versatile and intelligent clothing. We propose a strategy that may address the problems of silicon-based textile systems.