Showing papers in "Nano Letters in 2022"

Electrostatic Shielding Regulation of Magnetron Sputtered Al-Based Alloy Protective Coatings Enables Highly Reversible Zinc Anodes.

Abstract: The uncontrolled zinc dendrite growth during plating leads to quick battery failure, which hinders the widespread applications of aqueous zinc-ion batteries. The growth of Zn dendrites is often promoted by the "tip effect". In this work, we propose a generate strategy to eliminate the "tip effect" by utilizing the electrostatic shielding effect, which is achieved by coating Zn anodes with magnetron sputtered Al-based alloy protective layers. The Al can form a surface insulating Al2O3 layer and by manipulating the Al content of Zn-Al alloy films, we are able to control the strength of the electrostatic shield, therefore realizing a long lifespan of Zn anodes up to 3000 h at a practical operating condition of 1.0 mA cm-2 and 1.0 mAh cm-2. In addition, the concept can be extended to other Al-based systems such as Ti-Al alloy and achieve enhanced stability of Zn anodes, demonstrating the generality and efficacy of our strategy.

Hierarchical Confinement Effect with Zincophilic and Spatial Traps Stabilized Zn-Based Aqueous Battery.

Abstract: Zn-based aqueous batteries (ZABs) have been regarded as promising candidates for safe and large-scale energy storage in the "post-Li" era. However, kinetics and stability problems of Zn capture cannot be concomitantly regulated, especially at high rates and loadings. Herein, a hierarchical confinement strategy is proposed to design zincophilic and spatial traps through a host of porous Co-embedded carbon cages (denoted as CoCC). The zincophilic Co sites act as preferred nucleation sites with low nucleation barriers (within 0.5 mA h cm-2), and the carbon cage can further spatially confine Zn deposition (within 5.0 mA h cm-2). Theoretical simulations and in situ/ex situ structural observations reveal the hierarchical spatial confinement by the elaborated all-in-one network (within 12 mA h cm-2). Consequently, the elaborate strategy enables a dendrite-free behavior with excellent kinetics (low overpotential of ca. 65 mV at a high rate of 20 mA cm-2) and stable cycle life (over 800 cycles), pushing forward the next-generation high-performance ZABs.

Atomic Tuning of Single-Atom Fe-N-C Catalysts with Phosphorus for Robust Electrochemical CO2 Reduction.

Abstract: The electrochemical reduction of CO2 to produce carbon-based fuels and chemicals possesses huge potentials to alleviate current environmental problems. However, it is confronted by great challenges in the design of active electrocatalysts with low overpotentials and high product selectivity. Here we report the atomic tuning of a single-Fe-atom catalyst with phosphorus (Fe-N/P-C) on commercial carbon black as a robust electrocatalyst for CO2 reduction. The Fe-N/P-C catalyst exhibits impressive performance in the electrochemical reduction of CO2 to CO, with a high Faradaic efficiency of 98% and a high mass-normalized turnover frequency of 508.8 h-1 at a low overpotential of 0.34 V. On the basis of ex-situ X-ray absorption spectroscopy measurements and DFT calculations, we reveal that the tuning of P in single-Fe-atom catalysts reduces the oxidation state of the Fe center and decreases the free-energy barrier of *CO intermediate formation, consequently maintaining the electrocatalytic activity and stability of single-Fe-atom catalysts.

Theoretically Revealed and Experimentally Demonstrated Synergistic Electronic Interaction of CoFe Dual-Metal Sites on N-doped Carbon for Boosting Both Oxygen Reduction and Evolution Reactions.

Abstract: Heteronuclear double-atom catalysts, unlike single atom catalysts, may change the charge density of active metal sites by introducing another metal single atom, thereby modifying the adsorption energies of reaction intermediates and increasing the catalytic activities. First, density functional theory calculations are used to figure out the best combination by modeling two transition-metal atoms from Fe, Co, and Ni onto N-doped graphene. Generally, Fe and Co sites are highly active for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), respectively. The combination of Co and Fe to form CoFe-N-C not only further improves the Fe's ORR and Co's OER activities but also greatly enhances the Co site's ORR and Fe site's OER activities. Then, we synthesize the CoFe-N-C by a two-step pyrolysis process and find that the CoFe-N-C exhibits exceptional ORR and OER electrocatalytic activities in alkaline media, significantly superior to Fe-N-C and Co-N-C and even commercial catalysts.

Integration of Janus Wettability and Heat Conduction in Hierarchically Designed Textiles for All-Day Personal Radiative Cooling.

Abstract: Personal cooling textiles are a promising energy-free pathway for confronting serious heat-related public health threats and improving industrial worker productivity. Current cooling strategies mainly focus on passive daytime radiation, and there is a lack of research on all-day cooling methods which utilize synergistic radiative, conductive, and evaporative heat dissipation. Herein, we demonstrate a hierarchical polyurethane/silicon nitride fibrous membrane with Janus wettability fabricated via a scalable electrospinning method followed by single-side hydrophilic plasma treatment. High angular-dependent solar reflectance (91%) and human body infrared emittance (93%) allow for a temperature drop of ∼21.9 °C under direct sunlight and ∼2.8 °C at night compared with traditional cotton. The innovative integration of Janus wettability and heat conduction in hierarchically designed textiles ensures a minimum sweat consumption of 0.5 mL h-1, avoiding harmfully excessive perspiration. The excellent all-day cooling performance of this hierarchical textile presents great advantages for smart textile, energy-saving, and personal cooling applications.

Vertical Cu Nanoneedle Arrays Enhance the Local Electric Field Promoting C2 Hydrocarbons in the CO2 Electroreduction.

Abstract: Electrocatalytic reduction of CO2 to multicarbon products is a potential strategy to solve the energy crisis while achieving carbon neutrality. To improve the efficiency of multicarbon products in Cu-based catalysts, optimizing the *CO adsorption and reducing the energy barrier for carbon-carbon (C-C) coupling are essential features. In this work, a strong local electric field is obtained by regulating the arrangement of Cu nanoneedle arrays (CuNNAs). CO2 reduction performance tests indicate that an ordered nanoneedle array reaches a 59% Faraday efficiency for multicarbon products (FEC2) at -1.2 V (vs RHE), compared to a FEC2 of 20% for a disordered nanoneedle array (CuNNs). As such, the very high and local electric fields achieved by an ordered Cu nanoneedle array leads to the accumulation of K+ ions, which benefit both *CO adsorption and C-C coupling. Our results contribute to the design of highly efficient catalysts for multicarbon products.

Bi2O3/BiO2 Nanoheterojunction for Highly Efficient Electrocatalytic CO2 Reduction to Formate.

Abstract: Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel Bi2O3/BiO2 heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO2 reduction reaction (ECO2RR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized Bi2O3/BiO2 heterostructure can be transformed into a novel Bi/BiO2 Mott-Schottky heterostructure, leading to enhanced adsorption performance for CO2 and *OCHO intermediates. Consequently, high selectivity toward formate larger than 95% was rendered in a wide potential window along with an optimum partial current density of -111.42 mA cm-2 that benchmarked with the state-of-the-art Bi-based ECO2RR catalysts. This work reports the construction and fruitful structural dynamic insights of a novel heterojunction electrocatalyst for ECO2RR, which paves the way for the rational design of efficient heterojunction electrocatalysts for ECO2RR and beyond.

Site-Selective Adsorption on ZnF2/Ag Coated Zn for Advanced Aqueous Zinc-Metal Batteries at Low Temperature.

Abstract: Metallic Zn as a promising anode material of aqueous batteries suffers from severe parasitic reactions and notorious dendrite growth. To address these issues, the desolvation and nucleation processes need to be carefully regulated. Herein, Zn foils coated by ZnF2-Ag nanoparticles (ZnF2-Ag@Zn) are used as a model to modulate the desolvation and nucleation processes by hybrid surfaces, where Ag has a strong affinity to Zn adatoms and ZnF2 shows an intense adsorption to H2O. This selective adsorption of different species on ZnF2 and Ag reduces the mutual interference between two species. Therefore, ZnF2-Ag@Zn exhibits the electrochemical performance much better than ZnF2@Zn or Ag@Zn. Even at -40 °C, the full cells using ZnF2-Ag@Zn demonstrate an ultralong lifespan of 5000 cycles with a capacity retention of almost 100%. This work provides new insights to improve the performance of Zn metal batteries, especially at low temperatures.

Controllable Solid-Phase Fabrication of an Fe2O3/Fe5C2/Fe-N-C Electrocatalyst toward Optimizing the Oxygen Reduction Reaction in Zinc-Air Batteries.

Abstract: Preparing advanced electrocatalysts via solid-phase reactions encounters the challenge of low controllability for multiconstituent hybridization and microstructure modulation. Herein, a hydrothermal-mimicking solid-phase system is established to fabricate novel Fe2O3/Fe5C2/Fe-N-C composites consisting of Fe2O3/Fe5C2 nanoparticles and Fe,N-doped carbon species with varying morphologies. The evolution mechanism featuring a competitive growth of different carbon sources in a closed hypoxic space is elucidated for a series of Fe2O3/Fe5C2/Fe-N-C composites. The size and dispersity of Fe2O3/Fe5C2 nanoparticles, the graphitization degree of the carbonaceous matrix, and their diverse hybridization states lead to disparate electrocatalytic behaviors for the oxygen reduction reaction (ORR). Among them, microspherical Fe2O3/Fe5C2/Fe-N-C-3 exhibits an optimal ORR performance and the as-assembled zinc-air battery shows all-round superiority to the Pt/C counterpart. This work presents a mild solid-phase fabrication technique for obtaining a variety of nanocomposites with effective control over composition hybridization and microstructural modulation, which is significantly important for the design and optimization of advanced electrocatalysts.

Stabilizing Cobalt Single Atoms via Flexible Carbon Membranes as Bifunctional Electrocatalysts for Binder-Free Zinc-Air Batteries.

Abstract: Single-atom catalysts with high activity and efficient atom utilization have great potential in the electrocatalysis field, especially for rechargeable zinc-air batteries (ZABs). However, it is still a serious challenge to rationally construct a single-atom catalyst with satisfactory electrocatalytic activity and long-term stability. Here, we simultaneously realize the atomic-level dispersion of cobalt and the construction of carbon nanotube (CNT)-linked N-doped porous carbon nanofibers (NCFs) via an electrospinning strategy. In this hierarchical structure, the Co-N4 sites provide efficient oxygen reduction/evolution electrocatalytic activity, the porous architectures of NCFs guarantee the active site's accessibility, and the interior CNTs enhance the flexibility and mechanical strength of porous fibers. As a binder-free air cathode, the as-prepared catalysts deliver superdurability of 600 h at 10 mA cm-2 for aqueous ZABs and considerable flexibility and a small voltage gap for all-solid-state ZABs. This work provides an effective single-atom design/nanoengineering for superdurable zinc-air batteries.

Single-Atom Pt Anchored on Oxygen Vacancy of Monolayer Ti3C2Tx for Superior Hydrogen Evolution.

Abstract: Two-dimensional (2D) MXene-loaded single-atom (SA) catalysts have drawn increasing attention. SAs immobilized on oxygen vacancies (OV) of MXene are predicted to have excellent catalytic performance; however, they have not yet been realized experimentally. Here Pt SAs immobilized on the OV of monolayer Ti3C2Tx flakes are constructed by a rapid thermal shock technique under a H2 atmosphere. The resultant Ti3C2Tx-PtSA catalyst exhibits excellent hydrogen evolution reaction (HER) performance, including a small overpotential of 38 mV at 10 mA cm-2, a high mass activity of 23.21 A mgPt-1, and a large turnover frequency of 23.45 s-1 at an overpotential of 100 mV. Furthermore, density functional theory calculations demonstrate that anchoring the Pt SA on the OV of Ti3C2Tx helps to decrease the binding energy and the hybridization strength between H atoms and the supports, contributing to rapid hydrogen adsorption-desorption kinetics and high activity for the HER.

MXene-Based Aerogel Anchored with Antimony Single Atoms and Quantum Dots for High-Performance Potassium-Ion Batteries

Abstract: Rationally electronic structure engineering of nanocomposite electrodes shows great promise for enhancing the electrochemical performance of rechargeable batteries. Herein, we report antimony single atoms and quantum dots (∼5 nm) codecorated Ti3C2Tx MXene-based aerogels (Sb SQ@MA) for high-performance potassium-ion batteries (PIBs). We found that the atomically dispersed Sb could modify the electronic structure of the Sb/Ti3C2Tx composite, improve the charge transfer kinetics, and enhance the potassium storage capability at the heterointerfaces. Additionally, the MXene-based aerogel with rich surface functional groups and defects provides abundant anchoring sites and endows the composite reinforced structural stability and highly efficient electron transfer. The high loading of Sb (∼60.3 wt %) with short ionic transport pathways is desired potassium reservoirs. These features synergistically enhance the rate and cycling performance of the Sb SQ@MA electrodes in PIBs. This work has demonstrated an enlightening technique to tailor the interface activity of heterostructured electrodes for electrochemical applications.

Tetrahedral Framework Nucleic Acids Can Alleviate Taurocholate-Induced Severe Acute Pancreatitis and Its Subsequent Multiorgan Injury in Mice.

Abstract: Severe acute pancreatitis (SAP) is an inflammatory disease of the pancreas accompanied by tissue injury and necrosis. It not only affects the pancreas but also triggers a systemic inflammatory response that leads to multiorgan failure or even death. Moreover, there is no effective treatment currently that can reverse the disease progression. In this study, tetrahedral framework nucleic acids (tFNAs) were utilized to treat SAP in mice for the first time and proved to be effective in suppressing inflammation and preventing pathological cell death. Serum levels of pancreatitis-related biomarkers witnessed significant changes after tFNAs treatment. Reduction in the expression of certain cytokines involved in local and systemic inflammatory response were observed, together with alteration in proteins related to cell death and apoptosis. Collectively, our results demonstrate that tFNAs could both alleviate SAP and its subsequent multiorgan injury in mice, thus offering a novel and effective option to deal with SAP in the future.

ZnF2-Assisted Synthesis of Highly Luminescent InP/ZnSe/ZnS Quantum Dots for Efficient and Stable Electroluminescence.

Abstract: High-quality InP-based quantum dots (QDs) have become very promising, environmentally benign light emitters for display applications, but their synthesis generally entails hazardous hydrofluoric acid. Here, we present a highly facile route to InP/ZnSe/ZnS core/shell/shell QDs with a near-unity photoluminescence quantum yield. As the key additive, the inorganic salt ZnF2 mildly reacts with carboxylic acid at a high temperature and in situ generates HF, which eliminates surface oxide impurities, thus facilitating epitaxial shell growth. The resulting InP/ZnSe/ZnS QDs exhibit a narrower emission line width and better thermal stability in comparison with QDs synthesized with hydrofluoric acid. Light-emitting diodes using large-sized InP/ZnSe/ZnS QDs without replacing original ligands achieve the highest peak external quantum efficiency of 22.2%, to the best of our knowledge, along with a maximum brightness of >110 000 cd/m2 and a T95 lifetime of >32 000 h at 100 cd/m2. This safe approach is anticipated to be applied for a wide range of III-V QDs.

Tailoring Silver Nanowire Nanocomposite Interfaces to Achieve Superior Stretchability, Durability, and Stability in Transparent Conductors.

Abstract: Silver nanowires (AgNWs) have been considered as a promising candidate for transparent stretchable conductors (TSCs). However, the strong interface mismatch of stiff AgNWs and elastic substrates leads to the stress concentration at their interface and ultimately the low stretchability and poor durability of TSCs. Here, to address the interfacial mismatch of AgNWs-based TSCs we put forward a universal interface tailoring strategy that introduces the mercapto compound as the intermediate cross-linked layer. The mercapto compound strongly interacts with the AgNWs, forming a dense protective layer on their surface to improve their corrosion resistance, and reacts with the polymer substrate, forming a buffer layer to release the concentrated stress. As a result, the optimized TSCs showed superior stretchability (160%), exceptional durability (230 000 cycles), competent optoelectrical performance (18.0 ohm·sq-1 with a transmittance of 86.5%), and prominent stability. This work provides clear guidance and a strong impetus for the development of transparent stretchable electronics.

Interfacial Reduction Nucleation of Noble Metal Nanodots on Redox-Active Metal-Organic Frameworks for High-Efficiency Electrocatalytic Conversion of Nitrate to Ammonia.

Abstract: Electrochemically converting nitrate to ammonia is a promising route to realize artificial nitrogen recycling. However, developing highly efficient electrocatalysts is an ongoing challenge. Herein, we report the construction of stable and redox-active zirconium metal-organic frameworks (Zr-MOFs) based on Zr6 nanoclusters and redox-reversible tetrathiafulvalene (TTF) derivatives as inorganic nodes and organic linkers, respectively. The redox-active Zr-MOF can facilitate the in situ reduction of noble metal precursors free of external reductants and realize the uniform nucleation of noble metal nanodots (NDs) on Zr-MOF, achieving the preparation of M-NDs/Zr-MOF (M = Pd, Ag, or Au). The highly porous Zr-MOF with good conductivity can facilitate the mass transfer process. Among the M-NDs/Zr-MOF catalysts, Pd-NDs/Zr-MOF exhibits the highest electrocatalytic activity, delivering a NH3 yield of 287.31 mmol·h-1·g-1cat. and a Faradaic efficiency of 58.1%. The proposed interfacial reduction nucleation strategy for anchoring M NDs on Zr-MOFs can be applied to other challenging energy conversion reactions.

Unraveling the Synergistic Effect of Heteroatomic Substitution and Vacancy Engineering in CoFe2O4 for Superior Electrocatalysis Performance.

Abstract: Metal ion substitution and anion exchange are two effective strategies for regulating the electronic and geometric structure of spinel. However, the optimal location of foreign metallic cations and the exact role of these metals and anions remain elusive. Herein, CoFe2O4-based hollow nanospheres with outstanding oxygen evolution reaction activity are prepared by Cr3+ substitution and S2- exchange. X-ray absorption spectra and theoretical calculations reveal that Cr3+ can be precisely doped into octahedral (Oh) Fe sites and simultaneously induce Co vacancy, which can activate adjacent tetrahedral (Td) Fe3+. Furthermore, S2- exchange results in structure distortion of Td-Fe due to compressive strain effect. The change in the local geometry of Td-Fe causes the *OOH intermediate to deviate from the y-axis plane, thus enhancing the adsorption of the *OOH. The Co vacancy and S2- exchange can adjust the geometric and electronic structure of Td-Fe, thus activating the inert Td-Fe and improving the electrochemical performance.

Vacancy-Rich MoSSe with Sulfiphilicity-Lithiophilicity Dual Function for Kinetics-Enhanced and Dendrite-Free Li-S Batteries.

Abstract: The sluggish redox kinetics of sulfur and the uncontrollable growth of lithium dendrites are two main challenges that impede the practical applications of lithium-sulfur (Li-S) batteries. In this study, a multifunctional host with vacancy-rich MoSSe vertically grown on reduced graphene oxide aerogels (MoSSe/rGO) is designed as the host material for both sulfur and lithium. The embedding of Se into a MoS2 lattice is introduced to improve the inherent conductivity and generate abundant anion vacancies to endow the 3D conductive graphene based aerogels with specific sulfiphilicity-lithiophilicity. As a result, the assembled Li-S batteries based on MoSSe/rGO exhibit greatly improved capacity and cycling stability and can be operated under a lean electrolyte (4.8 μL mg-1) and a high sulfur loading (6.5 mg cm-2), achieving a high energy density. This study presents a unique method to unlock the catalysis capability and improve the inherent lithiophilicity by heteroatom doping and defect chemistry for kinetics-enhanced and dendrite-free Li-S batteries.

Ice-Assisted Synthesis of Highly Crystallized Prussian Blue Analogues for All-Climate and Long-Calendar-Life Sodium Ion Batteries

Abstract: For practical sodium-ion batteries, both high electrochemical performance and cost efficiency of the electrode materials are considered as two key parameters. Prussian blue analogues (PBAs) are broadly recognized as promising cathode materials due to their low cost, high theoretical capacity, and cycling stability, although they suffer from low-crystallinity-induced performance deterioration. Herein, a facile "ice-assisted" strategy is presented to prepare highly crystallized PBAs without any additives. By suppressing structure defects, the cathode exhibits a high capacity of 123 mAh g-1 with initial Coulombic efficiency of 87.2%, a long cycling lifespan of 3000 cycles, and significantly enhanced high/low temperature performance and calendar life. Remarkably, the low structure distortion and high sodium diffusion coefficient have been identified via in situ synchrotron powder diffraction and first-principles calculations, while its thermal stability has been analyzed by in situ heated X-ray powder diffraction. We believe the results could pave the way to the low-cost and large-scale application of PBAs in all-climate sodium-ion batteries.

Kinetics of Sorption in Hygroscopic Hydrogels.

Abstract: Hygroscopic hydrogels hold significant promise for high-performance atmospheric water harvesting, passive cooling, and thermal management. However, a mechanistic understanding of the sorption kinetics of hygroscopic hydrogels remains elusive, impeding an optimized design and broad adoption. Here, we develop a generalized two-concentration model (TCM) to describe the sorption kinetics of hygroscopic hydrogels, where vapor transport in hydrogel micropores and liquid transport in polymer nanopores are coupled through the sorption at the interface. We show that the liquid transport due to the chemical potential gradient in the hydrogel plays an important role in the fast kinetics. The high water uptake is attributed to the expansion of hydrogel during liquid transport. Moreover, we identify key design parameters governing the kinetics, including the initial porosity, hydrogel thickness, and shear modulus. This work provides a generic framework of sorption kinetics, which bridges the knowledge gap between the fundamental transport and practical design of hygroscopic hydrogels.

Efficient Zn Metal Anode Enabled by O,N-Codoped Carbon Microflowers.

Abstract: Zinc metal anodes show great promise for cheap and safe energy storage devices. However, it remains challenging to regulate highly efficient Zn plating/stripping under a high depth of discharge (DOD). Guided by density functional theory calculation, we here synthesized an oxygen- and nitrogen-codoped carbon superstructure as an efficient host for high-DOD Zn metal anodes through rational monomer selection, polymer self-assembly, and structure-preserved carbonization. With microscale 3D hierarchical structures, microcrystalline graphitic layers, and zincophilic heteroatom dopants, a flower-shaped carbon (Cflower) host could guide Zn nucleation and growth in a heteroepitaxial mode, affording horizontal plating with a high Coulombic efficiency (CE) and long life. As a demonstration, the Cflower-hosted Zn anode was paired with both battery and supercapacitor cathodes and delivered large capacity/capacitance, fast rates, long life, and ca. 100% CE even under a high DOD, outclassing hostless Zn-based devices. As they possess cheap, scalable, and efficient features, Cflower hosts hold the potential for practical zinc-metal-based energy devices.

Conductive Phosphine Oxide Passivator Enables Efficient Perovskite Light-Emitting Diodes.

Abstract: Recently, surface passivation has been proved to be an essential approach for obtaining efficient and stable perovskite light-emitting diodes (Pero-LEDs). Phosphine oxides performed well as passivators in many reports. However, the most commonly used phosphine oxides are insulators, which may inhibit carrier transport between the perovskite emitter and charge-transporter layers, limiting the corresponding device performance. Here, 2,7-bis(diphenylphosphoryl)-9,9'-spirobifluorene (SPPO13), a conductive molecule with two phosphine oxide functional groups, is introduced to modify the perovskite emitting layer. The bifunctional SPPO13 can passivate the nonradiative defects of perovskite and promote electron injection at the interface of perovskite emitter and electron-transporter layers. As a result, the corresponding Pero-LEDs obtain a maximum external quantum efficiency (EQE) of 22.3%. In addition, the Pero-LEDs achieve extremely high brightness with a maximum of around 190 000 cd/m2.

Artificial Vision Adaption Mimicked by an Optoelectrical In2O3 Transistor Array.

Abstract: Simulation of biological visual perception has gained considerable attention. In this paper, an optoelectrical In2O3 transistor array with a negative photoconductivity behavior is designed using a side-gate structure and a screen-printed ion-gel as the gate insulator. This paper is the first to observe a negative photoconductivity in electrolyte-gated oxide devices. Furthermore, an artificial visual perception system capable of self-adapting to environmental lightness is mimicked using the proposed device array. The transistor device array shows a self-adaptive behavior of light under different levels of light intensity, successfully demonstrating the visual adaption with an adjustable threshold range to the external environment. This study provides a new way to create an environmentally adaptive artificial visual perception system and has far-reaching significance for the future of neuromorphic electronics.

Dynamically Tunable All-Weather Daytime Cellulose Aerogel Radiative Supercooler for Energy-Saving Building.

Abstract: A passive cooling strategy without any electricity input has shown a significant impact on overall energy consumption globally. However, designing tunable daytime radiative cooler to meet requirement of different weather conditions is still a big challenge, especially in hot, humid regions. Here, a novel type of tunable, thermally insulating and compressible cellulose nanocrystal (CNC) aerogel coolers is prepared via chemical cross-linking and unidirectional freeze casting process. Such aerogel coolers can achieve a subambient temperature drop of 9.2 °C under direct sunlight and promisingly reached the reduction of ∼7.4 °C even in hot, moist, and fickle extreme surroundings. The tunable cooling performance can be realized via controlling the compression ratio of shape-malleable aerogel coolers. Furthermore, energy consumption modeling of using such aerogel coolers in buildings in China shows 35.4% reduction of cooling energy. This work can pave the way toward designing high-performance, thermal-regulating materials for energy consumption savings.

Robust, Healable, Self-Locomotive Integrated Robots Enabled by Noncovalent Assembled Gradient Nanostructure.

Abstract: Integration, being lightweight, and intelligence are important orientations for the future advancement of soft robots. However, existing soft robots are generally hydrogels or silicone rubber, which are inherently mechanically inferior and easily damaged and difficult to integrate functions. Here, inspired by nacre, an elastomer actuator with sulfonated graphene-based gradient nanostructures is constructed via supramolecular multiscale assembly. The resulting nanocomposite possesses an ultrahigh toughness of 141.19 MJ/m3 and high room-temperature self-healing efficiency (89%). The proof-of-concept robot is demonstrated to emphasize its maximum swimming speed of 2.67 body length per second, whose speed is comparable to that of plankton, representing the outperformance of most artificial soft robots. Furthermore, the robot can stably absorb pollutants and recover its robustness and functionality even when damaged. This study breaks the mutual exclusivity of functional execution and fast locomotions, and we anticipate that our nanostructural design will offer an effective extended path to other integrated robots that required multifunction integration.

Surface Electrostatics Govern the Emulsion Stability of Biomolecular Condensates

Abstract: Liquid-liquid phase separation underlies the formation of biological condensates. Physically, such systems are microemulsions that in general have a propensity to fuse and coalesce; however, many condensates persist as independent droplets in the test tube and inside cells. This stability is crucial for their function, but the physicochemical mechanisms that control the emulsion stability of condensates remain poorly understood. Here, by combining single-condensate zeta potential measurements, optical microscopy, tweezer experiments, and multiscale molecular modeling, we investigate how the nanoscale forces that sustain condensates impact their stability against fusion. By comparing peptide-RNA (PR25:PolyU) and proteinaceous (FUS) condensates, we show that a higher condensate surface charge correlates with a lower fusion propensity. Moreover, measurements of single condensate zeta potentials reveal that such systems can constitute classically stable emulsions. Taken together, these results highlight the role of passive stabilization mechanisms in protecting biomolecular condensates against coalescence.

Antiepilepticus Effects of Tetrahedral Framework Nucleic Acid via Inhibition of Gliosis-Induced Downregulation of Glutamine Synthetase and Increased AMPAR Internalization in the Postsynaptic Membrane.

Abstract: More than 15 million out of 70 million patients worldwide do not respond to available antiepilepticus drugs (AEDs). With the emergence of nanomedicine, nanomaterials are increasingly being used to treat many diseases. Here, we report that tetrahedral framework nucleic acid (tFNA), an assembled nucleic acid nanoparticle, showed an excellent ability to the cross blood-brain barrier (BBB) to inhibit M1 microglial activation and A1 reactive astrogliosis in the hippocampus of mice after status epilepticus. Furthermore, tFNA inhibited the downregulation of glutamine synthetase by alleviating oxidative stress in reactive astrocytes and subsequently reduced glutamate accumulation and glutamate-mediated neuronal hyperexcitability. Meanwhile, tFNA promotes α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) internalization in the postsynaptic membrane by regulating AMPAR endocytosis, which contributed to reduced calcium influx and ultimately reduced hyperexcitability and spontaneous epilepticus spike frequencies. These findings demonstrated tFNA as a potential AED and that nucleic acid material may be a new direction for the treatment of epilepsy.

Freestanding and Sandwich MXene-Based Cathode with Suppressed Lithium Polysulfides Shuttle for Flexible Lithium-Sulfur Batteries.

Abstract: Flexible lithium-sulfur (Li-S) batteries with high mechanical compliance and energy density are highly desired. This manuscript reported that large-area freestanding MXene (Ti3C2Tx) film has been obtained through a scalable drop-casting method, significantly improving adhesion to the sulfur layer under the continuously bent. Titanium oxide anchored on holey Ti3C2Tx (TiO2/H-Ti3C2Tx) was also produced by the well-controlled oxidation of few-layer Ti3C2Tx, which greatly facilitates lithium ion transport as well as prevents the shuttling of lithium polysulfides. Therefore, the obtained sandwich electrode has demonstrated a high capacity of 740 mAh g-1 at 2 C and a high capacity retention of 81% at 1 C after 500 cycles. Flexible Li-S batteries based on this sandwich electrode have a capacity retention as high as 95% after bending 500 times. This work provides effective design strategies of MXene for flexible batteries and wearable electronics.

Reconfigurable Magnetic Liquid Metal Robot for High-Performance Droplet Manipulation.

Abstract: Droplet manipulation is crucial for diverse applications ranging from bioassay to medical diagnosis. Current magnetic-field-driven manipulation strategies are mainly based on fixed or partially tunable structures, which limits their flexibility and versatility. Here, a reconfigurable magnetic liquid metal robot (MLMR) is proposed to address these challenges. Diverse droplet manipulation behaviors including steady transport, oscillatory transport, and release can be achieved by the MLMR, and their underlying physical mechanisms are revealed. Moreover, benefiting from the magnetic-field-induced active deformability and temperature-induced phase transition characteristics, its droplet-loading capacity and shape-locking/unlocking switching can be flexibly adjusted. Because of the fluidity-based adaptive deformability, MLMR can manipulate droplets in challenging confined environments. Significantly, MLMR can accomplish cooperative manipulation of multiple droplets efficiently through on-demand self-splitting and merging. The high-performance droplet manipulation using the reconfigurable and multifunctional MLMR unfolds new potential in microfluidics, biochemistry, and other interdisciplinary fields.

Quantitative Evaluation of Carrier Dynamics in Full-Spectrum Responsive Metallic ZnIn2S4 with Indium Vacancies for Boosting Photocatalytic CO2 Reduction.

Abstract: The influence of defects on quantitative carrier dynamics is still unclear. Therefore, full-spectrum responsive metallic ZnIn2S4 (VIn-rich-ZIS) rich in indium vacancies and exhibiting high CO2 photoreduction efficiency was synthesized for the first time. The influence of the defects on the carrier dynamic parameters was studied quantitatively; the results showed that the minority carrier diffusion length (LD) is closely related to the catalytic performance. In situ infrared spectroscopy and theoretical calculations revealed that the presence of indium vacancies lowers the energy barrier for CO2 to CO conversion via the COOH* intermediate. Hence, the high rate of CO evolution reaches 298.0 μmol g-1 h-1, a nearly 28-fold enhancement over that with ZnIn2S4 (VIn-poor-ZIS), which is not rich in indium vacancies. This work fills the gaps between the catalytic performance of defective photocatalysts and their carrier dynamics and may offer valuable insight for understanding the mechanism of photocatalysis and designing more efficient defective photocatalysts.