Ordered Structures with Functional Units as a Paradigm of Material Design

A Promising Deep Ultraviolet Nonlinear Optical Crystal Activated by the Ordered Structure Design

Deep-ultraviolet nonlinear optical (DUV NLO) crystals play a vitally important role in many scientific and technological fields, yet their rational design remains an ongoing challenge. Here, through utilizing the ordered structure design, a new KBe2BO3F2-like DUV transparent NLO crystal Cs2KY(B3O6)2 has been successfully designed and synthesized, in which we first use the largest π-conjugated B3O6 functional groups to substitute the BO3 to maximize the second-harmonic generation (SHG) response and utilize the K/YO6 connecting groups to replace two BeO3F groups to optimize the layer connections. Eventually, Cs2KY(B3O6)2 exhibits not only the largest SHG responses in KBe2BO3F2-like DUV borates but also the best growth rate along c axis (the strong layer-habit along c axis has been being the greatest obstacle to prohibit the practical application of KBe2BO3F2 and its derivative). Clearly, the substitution from BO3 triangles to similar topological B3O6 groups and from (BeO3F)2 groups to similar topological K/YO6 octahedra can better modulate the functional properties of materials in the larger scale. That results in the superior comprehensive properties of Cs2KY(B3O6)2 and makes it a promising DUV NLO crystal. Therefore, the ordered structure design provides some new insights for assembling the functional and connecting groups to rationally design materials with high-performance.

Lessons from Nature: Advances and Perspectives in Bionic Microwave Absorption Materials

Inspired by the remarkable electromagnetic response capabilities of the complex morphologies and subtle microstructures evolved by natural organisms, this paper delves into the research advancements and future application potential of bionic microwave-absorbing materials (BMAMs). It outlines the significance of achieving high-performance microwave-absorbing materials through ingenious microstructural design and judicious composition selection, while emphasizing the innovative strategies offered by bionic manufacturing. Furthermore, this work meticulously analyzes how inspiration can be drawn from the intricate structures of marine organisms, plants, animals, and non-metallic minerals in nature to devise and develop BMAMs with superior electromagnetic wave absorption properties. Additionally, the paper provides an in-depth exploration of the theoretical underpinnings of BMAMs, particularly the latest breakthroughs in broadband absorption. By incorporating advanced methodologies such as simulation modeling and bionic gradient design, we unravel the scientific principles governing the microwave absorption mechanisms of BMAMs, thereby furnishing a solid theoretical foundation for understanding and optimizing their performance. Ultimately, this review aims to offer valuable insights and inspiration to researchers in related fields, fostering the collective advancement of research on BMAMs.

Ultrafast Joule Heating Modification of Methane-Pyrolyzed Carbon Black for Supercapacitor Application

Carbon black from methane pyrolysis for hydrogen is an alternative resource and can be improved for conductive material supplication. Our current work uses an ultrafast Joule heating technique to modify the methane-pyrolyzed carbon black and prepare nanoparticles of electrode material for supercapacitor application, coupled with density functional theory, structural, and electrochemical analyses. Evolution rules of the carbon and pore structures of the modified sample with an increase in temperature reveal good structure improvements. The graphitization degree of modified carbon black nanoparticles increases, and the particle morphology changes from a smooth surface, disordered structure removal, and pore formation to graphite crystallization. Band structure and state density analytical results show that the modified carbon black with a defect-free structure possesses metallic properties and exhibits good electrical conductivity. A temperature around 1576 °C to the initial graphitization was defined based on the critical point of the evolution of ordered and disordered structures, while the electrical conductivity of the carbon black nanoparticles at 2000 °C reaches 2300 S/m. The modified carbon black performed with stable charge/discharge characteristics, exhibiting a 4.31% capacitance drop at a current load of 2 A/g and a 18.31% capacitance drop at a current load of 20 A/g.

Zero Voltage-Degradation of Li2MnO3 with Ultrathin Amorphous Li─Mn─O Coating

Manganese-based lithium-rich layered oxides (Mn-LLOs) are promising candidate cathode materials for lithium-ion batteries, however, the severe voltage decay during cycling is the most concern for their practical applications. Herein, an Mn-based composite nanostructure constructed Li2MnO3 (LMO@Li2MnO3) is developed via an ultrathin amorphous functional oxide LixMnOy coating at the grain surface. Due to the thin and universal LMO amorphous surface layer etched from the lithiation process by the high-concentration alkaline solution, the structural and interfacial stability of Li2MnO3 are enhanced apparently, showing the significantly improved voltage maintenance, cycle stability, and energy density. In particular, the LMO@Li2MnO3 cathode exhibits zero voltage decay over 200 cycles. Combining with ex situ spectroscopic and microscopic techniques, the Mn2+/4+ coexisted behavior of the amorphous LMO is revealed, which enables the stable electrochemistry of Li2MnO3. This work provides new possible routes for suppressing the voltage decay of Mn-LLOs by modifying with the composite functional unit construction.

Ordered Perovskite Structure with Functional Units for High Performance and Stable Solar Cells

Ion migration is one of the most critical challenges that affects the stability of metal-halide perovskite solar cells (PSCs). However, the current arsenal of available strategies for solving this issue is limited. Here, novel perovskite active layers following the concept of ordered structures with functional units (OSFU) to intrinsically suppress ion migration, in which a three-dimensional (3D) perovskite layer is deposited by vapor deposition for light absorption and a 2D layer is deposited by solution process for ion inhibition, are constructed. As a promising result, the activation energy of ion migration increases from 0.36 eV for the conventional perovskite to 0.54 eV for the OSFU perovskite. These devices exhibit substantially enhanced operational stability in comparison with the conventional ones, retaining >85% of their initial efficiencies after 1200 h under ISOS-L-1. Moreover, the OSFU devices show negligible fatigue behavior with a robust performance under light/dark cycling aging test (ISOS-LC-1 protocol), which demonstrates the promising application of functional motif theory in this field.

Superstructure-Induced Hierarchical Assemblies for Nanoconfined Photocatalysis

Most attempts to synthesize supramolecular nanosystems are limited to a single mechanism, often resulting in the formation of nanomaterials that lack diversity in properties. Herein, hierarchical assemblies with appropriate variety are fabricated in bulk via a superstructure-induced organic-inorganic hybrid strategy. The dynamic balance between substructures and superstructures is managed using covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) as dual building blocks to regulate the performances of hierarchical assemblies. Significantly, the superstructures resulting from the controlled cascade between COFs and MOFs create highly active photocatalytic systems through multiple topologies. Our designed tandem photocatalysis can precisely and efficiently regulate the conversion rates of bioactive molecules (benzo[d]imidazoles) through competing redox pathways. Furthermore, benzo[d]imidazoles catalyzed by such supramolecular nanosystems can be isolated in yields ranging from 70 % to 93 % within tens of minutes. The multilayered structural states within the supramolecular systems demonstrate the importance of hierarchical assemblies in facilitating photocatalytic propagation and expanding the structural repertoire of supramolecular hybrids.

Establishing a unified paradigm of microwave absorption inspired by the merging of traditional microwave absorbing materials and metamaterials

The merging of traditional microwave absorbing materials with metamaterials holds significant potential for enhancing microwave absorber performance. To unlock this potential, a unified paradigm is urgently required. We have successfully established such a paradigm, focusing on regulating effective electromagnetic parameters and interfacial forms across microscopic, mesoscopic, and macroscopic scales. Building upon this foundation, we introduce an active co-design methodology for jointly optimizing full-scale structures and the concept of "full-scale microwave absorbers" (FSMAs). Under this guidance, performance improvements can be achieved efficiently, leading to crucial breakthroughs. For demonstration, we present a case study designing ultra-thin miniaturized FSMAs capable of ultra-broadband and low-frequency absorption. Simulation results show absorptivity exceeding 90% in the 2-28 GHz range, with absorptivity surpassing 85% and 74% in the 1.5-2 GHz and 1-1.5 GHz ranges, respectively. Additionally, the total thickness and macro period are only 5 mm, roughly equivalent to 0.033 wavelengths of the lowest operating frequency. Most importantly, we have broken the Rozanov limit, with experimental results further validating this design. This work significantly enhances our understanding of microwave absorption and offers a shortcut for pursuing improved performances and breakthroughs.

A Stress Self-Adaptive Silicon/Carbon "Ordered Structures" to Suppress the Electro-Chemo-Mechanical Failure: Piezo-Electrochemistry and Piezo-Ionic Dynamics

Construction of ordered structures that respond rapidly to environmental stimuli has fascinating possibilities for utilization in energy storage, wearable electronics, and biotechnology. Silicon/carbon (Si/C) anodes with extremely high energy densities have sparked widespread interest for lithium-ion batteries (LIBs), while their implementation is constrained via mechanical structure deterioration, continued growth of the solid electrolyte interface (SEI), and cycling instability. In this study, a piezoelectric Bi0.5 Na0.5 TiO3 (BNT) layer is facilely deposited onto Si/C@CNTs anodes to drive piezoelectric fields upon large volume expansion of Si/C@CNTs electrode materials, resulting in the modulation of interfacial Li+ kinetics during cycling and providing an electrochemical reaction with a mechanically robust and chemically stable substrate. In-depth investigations into theoretical computation, multi-scale in/ex situ characterizations, and finite element analysis reveal that the improved structural stability, suppressed volume variations, and controlled ion transportation are responsible for the improvement mechanism of BNT decorating. These discoveries provide insight into the surface coupling technique between mechanical and electric fields to control the interfacial Li+ kinetics behavior and improve structural stability for alloy-based anodes, which will also spark a great deal attention from researchers and technologists in multifunctional surface engineering for electrochemical systems.

Reconfigurable mechano-responsive soft film for adaptive visible and infrared dual-band camouflage

Learning from nature in terms of the camouflage used by species has enabled the continuous development of camouflage technologies for the visible to mid-infrared bands to prevent objects from being detected by sophisticated multispectral detectors, thereby avoiding potential threats. However, achieving visible and infrared dual-band camouflage without destructive interference while also realizing rapidly responsive adaptivity to the varying background remains challenging for high-demand camouflage systems. Here, we report a reconfigurable mechano-responsive soft film for dual-band camouflage. Its modulation ranges for visible transmittance and longwave infrared emittance can be up to 66.3% and 21%, respectively. Rigorous optical simulations are performed to elucidate the modulation mechanism of dual-band camouflage and identify the optimal wrinkles required to achieve the goal. The broadband modulation capability (figure of merit) of the camouflage film can be as high as 2.91. Other advantages, such as simple fabrication and a fast response, make this film a potential candidate for dual-band camouflage that can adapt to diverse environments.

Perspective and Prospects for Ordered Functional Materials

Many functional materials are approaching their performance limits due to inherent trade-offs between essential physical properties. Such trade-offs can be overcome by engineering a material that has an ordered arrangement of structural units, including constituent components/phases, grains, and domains. By rationally manipulating the ordering with abundant structural units at multiple length scales, the structural ordering opens up unprecedented opportunities to create transformative functional materials, as amplified properties or disruptive functionalities can be realized. In this perspective article, a brief overview of recent advances in the emerging ordered functional materials across catalytic, thermoelectric, and magnetic materials regarding the fabrication, structure, and property is presented. Then the possibility of applying this structural ordering strategy to highly efficient neuromorphic computing devices and durable battery materials is discussed. Finally, remaining scientific challenges are highlighted, and the prospects for ordered functional materials are made. This perspective aims to draw the attention of the scientific community to the emerging ordered functional materials and trigger intense studies on this topic.

High-Throughput Scanning Second-Harmonic-Generation Microscopy for Polar Materials

The Materials Genome Initiative aims to discover, develop, manufacture, and deploy advanced materials at twice the speed of conventional approaches. To achieve this, high-throughput characterization is essential for the rapid screening of candidate materials. In this study, a high-throughput scanning second-harmonic-generation microscope with automatic partitioning, accurate positioning, and fast scanning is developed that can rapidly probe and screen polar materials. Using this technique, typical ferroelectrics, including periodically poled lithium niobate crystals and PbZr_0.2 Ti_0.8 O₃ (PZT) thin films are first investigated, whereby the microscopic domain structures are clearly revealed. This technique is then applied to a compositional-gradient (100-x)%BaTiO₃ -x%SrTiO₃ film and a thickness-gradient PZT film to demonstrate its high-throughput capabilities. Since the second-harmonic-generation signal is correlated with the macroscopic remnant polarization over the probed region determined by the laser spot, it is free of artifacts arising from leakage current and electrostatic interference, while materials' symmetries and domain structures must be carefully considered in the data analysis. It is believed that this work can help promote the high-throughput development of polar materials and contribute to the Materials Genome Initiative.

Bioinspired multiple-degrees-of-freedom responsive metasurface by high-entropy-alloy ribbons with hierarchical nanostructures for electromagnetic wave absorption

The compound eyes of the dragonfly, Pantala flavescens Fabricius, are covered by micro-scaled ocelli capable of sensing polarized light, an attractive property for radar stealth and counterreconnaissance. In this work, we fabricated biomimetic electromagnetic wave absorption materials (EAMs) by analyzing the covert information identifications of biological systems and focusing on the design of metastructures and microstructures. Several bionic metasurfaces with anisotropic double-V meta atoms made up of (FeCoNiSi_8.9Al_8.9)C_0.2 high-entropy-alloy (HEA) ribbons for multiple-degrees-of-freedom recognition and broadband absorption are presented. The covert phase, amplitude, and angular momentum of electromagnetic waves were controlled and recognized as information by manipulating the rotation angle θ of meta atoms. A vortex wave with a topological charge of 1 was generated to recognize linearly polarization and left- and right-handed circular polarization. In addition, the polarization conversion enhanced absorption. The hierarchical nanostructures of HEA ribbons give rise to suitable electromagnetic loss and a superior impedance match. Finally, inspired by the structure of compound eyes, the designed multilayer metamaterials realized effective absorption (reflection loss (RL) ≤  - 10 dB) within the 4.5-18 GHz regime under 2.8 mm thickness. These materials provide evidence for a new way for integrated EAMs and metamaterials.

Nano-biotechnology in tumour and cancerous disease: A perspective review

In recent years, drug manufacturers and researchers have begun to consider the nanobiotechnology approach to improve the drug delivery system for tumour and cancer diseases. In this article, we review current strategies to improve tumour and cancer drug delivery, which mainly focuses on sustaining biocompatibility, biodistribution, and active targeting. The conventional therapy using cornerstone drugs such as fludarabine, cisplatin etoposide, and paclitaxel has its own challenges especially not being able to discriminate between tumour versus normal cells which eventually led to toxicity and side effects in the patients. In contrast to the conventional approach, nanoparticle-based drug delivery provides target-specific delivery and controlled release of the drug, which provides a better therapeutic window for treatment options by focusing on the eradication of diseased cells via active targeting and sparing normal cells via passive targeting. Additionally, treatment of tumours associated with the brain is hampered by the impermeability of the blood-brain barriers to the drugs, which eventually led to poor survival in the patients. Nanoparticle-based therapy offers superior delivery of drugs to the target by breaching the blood-brain barriers. Herein, we provide an overview of the properties of nanoparticles that are crucial for nanotechnology applications. We address the potential future applications of nanobiotechnology targeting specific or desired areas. In particular, the use of nanomaterials, biostructures, and drug delivery methods for the targeted treatment of tumours and cancer are explored.

K3C6N7O3·2H2O: A Multifunctional Nonlinear Optical Cyamelurate Crystal with Colossal π-Conjugated Orbitals

The delocalized π-conjugated units are considered as an advantageous gene for improving the optical nonlinearity of acentric crystals. For the first time, we synthesized a new acentric SHG-active metal cyamelurate crystal K₃C₆N₇O₃·2H₂O (I) by a facile solution method, containing a colossal planar π-conjugated (C₆N₇O₃)^3- unit. It displays a strong second-order harmonic generation (SHG) of 4 × KDP and a giant anisotropic birefringence of 0.446 at 1064 nm. The theoretical calculations reveal that such substantial improvement is contributed from the strong molecular susceptibility of (C₆N₇O₃)^3- units and their near-perfect coplanar arrangement. Moreover, I exhibits a broadband ultraviolet photoluminescence at 366 nm, suggesting its multifunctional capacity and great potential for compact highly integrated optoelectronic devices.

Wireless Miniature Magnetic Phase-Change Soft Actuators

Wireless miniature soft actuators are promising for various potential high-impact applications in medical, robotic grippers, and artificial muscles. However, these miniature soft actuators are currently constrained by a small output force and low work capacity. To address such challenges, a miniature magnetic phase-change soft composite actuator is reported. This soft actuator exhibits an expanding deformation and enables up to a 70 N output force and 175.2 J g-1 work capacity under remote magnetic radio frequency heating, which are 106 -107 times that of traditional magnetic soft actuators. To demonstrate its capabilities, a wireless soft robotic device is first designed that can withstand 0.24 m s-1 fluid flows in an artery phantom. By integrating it with a thermally-responsive shape-memory polymer and bistable metamaterial sleeve, a wireless reversible bistable stent is designed toward future potential angioplasty applications. Moreover, it can additionally locomote inside and jump out of granular media. At last, the phase-change actuator can realize programmable bending deformations when a specifically designed magnetization profile is encoded, enhancing its shape-programming capability. Such a miniature soft actuator provides an approach to enhance the mechanical output and versatility of magnetic soft robots and devices, extending their medical and other potential applications.

Gradient Annealing as a New Strategy to Fabricate Gradient Nanoparticle Array on Microwires

Creating gradients of nanostructure on the surface has found broad applications such as enhanced optical spectroscopy, optical storage of information, and broadband solar energy harvesting. Here, a facile strategy is presented for fabricating gradient nanoparticle arrays with tunable size. It takes a ZnO:Ga microwire as the starting material, and the Ga³⁺ doping gradient along the microwire is induced by the high voltage applied. Such a doping gradient facilitates the formation of a temperature gradient in a Joule heating process. And this temperature gradient produced by this technique can be as high as 800 °C/mm, which could be later used for gradient annealing of thin metal films. After annealing, the thin metal films turn to gradient nanoparticle arrays. The obtained gradient nanoparticle arrays are confirmed effective in multi-wavelength surface enhanced Raman scattering enhancement.

Strong, Water-Resistant, and Ionic Conductive All-Chitosan Film with a Self-Locking Structure

Renewable and biodegradable natural polymeric materials are attractive candidates for replacing nonbiodegradable plastics. However, it is challenging to fabricate polysaccharide-based materials (such as cellulose and chitin) that can be used in humid or even watery environments due to their inferior stability against water. Here, a self-locking structure is constructed to develop a strong, water-resistant, and ionic conductive all-chitosan film without other additives. The densely packed self-locking structure introduces strong interactions between chitosan nanofibers, preventing the fibers from disentangling even in watery environments. The resulting film exhibits outstanding tensile strength of ∼144 MPa, superior wet strength of ∼54.3 MPa, and high ionic conductivity of 0.0012 S/cm at 10-4 M KCl, which are significantly higher than those of conventional polysaccharide-based materials and many commercially used plastics. Additionally, it also possesses outstanding flexibility, excellent thermal stability, good antimicrobial ability, and biodegradability, which make it a promising eco-friendly alternative to plastics for many potential applications, such as packaging bags, drinking straws, and ion regulation membranes.

Mechanically Reinforced Silkworm Silk Fiber by Hot Stretching

Silkworm silk, which is obtained from domesticated Bombyx mori (B. mori), can be produced in a large scale. However, the mechanical properties of silkworm silk are inferior to its counterpart, spider dragline silk. Therefore, researchers are continuously exploring approaches to reinforce silkworm silk. Herein, we report a facile and scalable hot stretching process to reinforce natural silk fibers obtained from silkworm cocoons. Experimental results show that the obtained hot-stretched silk fibers (HSSFs) retain the chemical components of the original silk fibers while being endowed with increased β-sheet nanocrystal content and crystalline orientation, leading to enhanced mechanical properties. Significantly, the average modulus of the HSSFs reaches 21.6 ± 2.8 GPa, which is about twice that of pristine silkworm silk fibers (11.0 ± 1.7 GPa). Besides, the tensile strength of the HSSFs reaches 0.77 ± 0.13 GPa, which is also obviously higher than that of the pristine silk (0.56 ± 0.08 GPa). The results show that the hot stretching treatment is effective and efficient for producing superstiff, strong, and tough silkworm silk fibers. We anticipate this approach may be also effective for reinforcing other natural or artificial polymer fibers or films containing abundant hydrogen bonds.

Inverse Design of Ferroelectric-Order in Perovskite Crystal for Self-Powered Ultraviolet Photodetection

It has always been a hot topic to design an orderly mesoscopic structure in functional materials to tailor the macroscopic properties or realize new functions. The existence of domains in ferroelectric materials has been proven to affect the macroscopic properties, being actively studied in nonlinear optical conversion and piezoelectric effects. However, the high-efficiency photoelectric conversion capability of ferroelectric crystals has not yet been explored. Here, the authors study the orderly arrangement of ferroelectric order in KTa_{1- x} Nb_x O₃ (KTN) perovskite crystals, and design the "head-to-head" domains by tuning the Curie temperature T_c , thereby generating abundant charged domain walls and robust conductive channels for electrons and holes. An ultrahigh ultraviolet photoresponsivity is achieved in the KTN crystal under zero bias voltage, being about four orders magnitude higher than that of the well-known ferroelectric materials. The substantial improvement can be attributed to the judiciously designed ferroelectric order, as demonstrated by the conductive atomic force microscopy. In addition, KTN detector exhibits high stability and reliability after high-temperature and fatigue treatment. KTN crystal features giant photoresponsivity, high electric-optical coefficient, and large χ⁽²⁾ nonlinearity concurrently, indicating its great potential for application of all-optical devices on photonic chips.

Designing Artificial Vibration Modes of Piezoelectric Devices Using Programmable, 3D Ordered Structure with Piezoceramic Strain Units

Piezoelectric ceramic devices, which utilize multifarious vibration modes to realize electromechanical coupling and energy conversions, are extensively used in high-technological fields. However, the excitation of basic modes is mainly subjected to natural eigenfrequency of ceramic devices, which is related to the structure and material parameters. Herein, inspired by metamaterial theory, a programmable, 3D ordered structure with piezoceramic strain units (3D OSPSU) is developed to artificially generate basic modes in a broad frequency band other than only in narrow eigenfrequency. A (2 × 2 × 2) arrayed, co-fired, multilayer 3D OSPSU is painstakingly designed and fabricated for generating basic modes, such as flexural, extension, shear, torsion, and even coupled modes at nonresonance. To validate the 3D OSPSU method, a five-degree-of-freedom micro-nano actuating platform based on only one co-fired multilayer ceramic is constructed. The proposed methodology provides a new paradigm for creating extraordinary material properties of piezoelectric ceramics and will inspire brand-new piezoelectric device designs.

Microscale Silicon-Based Anodes: Fundamental Understanding and Industrial Prospects for Practical High-Energy Lithium-Ion Batteries

To accelerate the commercial implementation of high-energy batteries, recent research thrusts have turned to the practicality of Si-based electrodes. Although numerous nanostructured Si-based materials with exceptional performance have been reported in the past 20 years, the practical development of high-energy Si-based batteries has been beset by the bias between industrial application with gravimetrical energy shortages and scientific research with volumetric limits. In this context, the microscale design of Si-based anodes with densified microstructure has been deemed as an impactful solution to tackle these critical issues. However, their large-scale application is plagued by inadequate cycling stability. In this review, we present the challenges in Si-based materials design and draw a realistic picture regarding practical electrode engineering. Critical appraisals of recent advances in microscale design of stable Si-based materials are presented, including interfacial tailoring of Si microscale electrode, surface modification of SiO_x microscale electrode, and structural engineering of hierarchical microscale electrode. Thereafter, other practical metrics beyond active material are also explored, such as robust binder design, electrolyte exploration, prelithiation technology, and thick-electrode engineering. Finally, we provide a roadmap starting with material design and ending with the remaining challenges and integrated improvement strategies toward Si-based full cells.

Material exploration via designing spatial arrangement of octahedral units: a case study of lead halide perovskites

Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications. The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials. At present, most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units, whereas designing the spatial arrangement of the functional units has received relatively little consideration. In this work, via a global structure search based on density functional theory (DFT), we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge- and corner-sharing. We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape, such as 2,2'-bisimidazole (BIM). DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2I6, synthesized through a solution process, exhibits high electronic dimensionality, a direct allowed bandgap of 2.1 eV, small effective masses for both electrons and holes, and high optical absorption coefficients, which indicates a significant potential for optoelectronic applications. The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.

Full Concentration Gradient-Tailored Li-Rich Layered Oxides for High-Energy Lithium-Ion Batteries

Lithium-rich layered oxides (LLOs) are prospective cathode materials for next-generation lithium-ion batteries (LIBs), but severe voltage decay and energy attenuation with cycling still hinder their practical applications. Herein, a series of full concentration gradient-tailored agglomerated-sphere LLOs are designed with linearly decreasing Mn and linearly increasing Ni and Co from the particle center to the surface. The gradient-tailored LLOs exhibit noticeably reduced voltage decay, enhanced rate performance, improved cycle stability, and thermal stability. Without any material modifications or electrolyte optimizations, the gradient-tailored LLO with medium-slope shows the best electrochemical performance, with a very low average voltage decay of 0.8 mV per cycle as well as a capacity retention of 88.4% within 200 cycles at 200 mA g^-1 . These excellent findings are due to spinel structure suppression, electrochemical stress optimization, and Jahn-Teller effect inhibition. Further investigation shows that the gradient-tailored LLO reduces the thermal release percentage by as much as about 41% when the battery is charged to 4.4 V. This study provides an effective method to suppress the voltage decay of LLOs for further practical utilization in LIBs and also puts forward a bulk-structure design strategy to prepare better electrode materials for different rechargeable batteries.

Coupled Vacancy Pairs in Ni-Doped CoSe for Improved Electrocatalytic Hydrogen Production Through Topochemical Deintercalation

Vacancy engineering plays vital role in the design of high-performance electrocatalysts. Here, we introduced coupled cation-vacancy pairs in Ni-doped CoSe to achieve boosted hydrogen evolution reaction (HER) activity through a facile topochemical intercalation approach. Adjacent Co vacancy pairs and heteroatom Ni doping contribute together for the upshift of the Se 4p_z orbital, which induces larger overlap between the Se 4p and H 1s orbitals. As a result, the free energy of H adsorption can be lowered significantly. With an advanced HER activity of 185.7 mV at 10 mA cm^-2 , this work provides new direction and guidance for the design of novel electrocatalysts.

Long-Range Ordered Amorphous Atomic Chains as Building Blocks of a Superconducting Quasi-One-Dimensional Crystal

Crystalline and amorphous structures are two of the most common solid-state phases. Crystals having orientational and periodic translation symmetries are usually both short-range and long-range ordered, while amorphous materials have no long-range order. Short-range ordered but long-range disordered materials are generally categorized into amorphous phases. In contrast to the extensively studied crystalline and amorphous phases, the combination of short-range disordered and long-range ordered structures at the atomic level is extremely rare and so far has only been reported for solvated fullerenes under compression. Here, a report on the creation and investigation of a superconducting quasi-1D material with long-range ordered amorphous building blocks is presented. Using a diamond anvil cell, monocrystalline (TaSe₄ )₂ I is compressed and a system is created where the TaSe₄ atomic chains are in amorphous state without breaking the orientational and periodic translation symmetries of the chain lattice. Strikingly, along with the amorphization of the atomic chains, the insulating (TaSe₄ )₂ I becomes a superconductor. The data provide critical insight into a new phase of solid-state materials. The findings demonstrate a first ever case where superconductivity is hosted by a lattice with periodic but amorphous constituent atomic chains.

Chameleon-Inspired Stress-Responsive Multicolored Ultratough Films

Chameleons have a distinguished talent to rapidly shift their colors by active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores. This reversible structural color variation is derived from the birefringence, which is triggered by the special anisotropic structure interacting with natural light. Inspired by the inorganic oligomers and their superiorities for constructing ultratough materials with a special structure, we demonstrated here a chameleon's skin-like film constructed by ultrasmall calcium phosphate oligomers (∼1.75 nm in diameter) as the precursor of crystalline hydroxyapatite nanoline (HNL) arrays and polyvinyl alcohol as the elastic matrix. The resulting films exhibit excellent toughness (48.3 ± 5.2 MJ m^-3). Under the applied cyclic stress, the HNLs embedded in the polymer network can reversibly arrange into a highly ordered crystal arrays owing to the driving action of polymer chains. The intense birefringence of the stretched films is easily observed with the naked eye under crossed polarizers, allowing for rapid and simple measurement of the applied stress. This work provides a pathway for the development of functional composites with super toughness by ultrasmall inorganic oligomers for their potential applications in smart devices for stress detection.

Designing Ordered Structure with Piezoceramic Actuation Units (OSPAU) for Generating Continual Nanostep Motion

Continual precision actuations with nanoscale resolution over large ranges have extensive requirements in advanced intelligent manufacturing and precise surgical robots. To produce continual nanostep motion, conventionally, multiple pairs of piezo-actuators are employed to operate in inchworm principle under complex three- or four-phase timing signal drive. Inspired by the idea of ordered structures with functional units, a much simpler nanostep piezoelectric actuator consisting of (2 × 2) arrayed, cofired multilayer piezoceramic actuation units is developed, which operates in an artificially generated quasi shear mode (AGQSM) that is missing in natural piezoelectric ceramics. Under only one-phase square-wave voltage drive, the actuator can produce a stable, continual nanostep motion in two ways at nonresonant frequencies, and the obtained minimum step displacement is as low as 7 nm in open control, indicating its potential application as a precise finger or knife actuator in surgical robots. This work is of great guiding significance for future actuator designs using the methodology of ordered structure with piezoceramic actuation units and AGQSM.

Significantly Enhanced Thermoelectric Properties of Organic-Inorganic Hybrids with a Periodically Ordered Structure

The deficient order in amorphous components severely affects the thermoelectric (TE) properties in polymers. Encouragingly, two-dimensional layered double hydroxides (LDHs) have been regarded as an efficient host material to tune the conformation of guest molecules and construct ordered hybrids. Herein, we report a facile construction of periodically ordered organic-inorganic TE hybrids by alternative stacking of inorganic LDH nanosheets and organic poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) molecules. The ordered structure of PEDOT:PSS-LDH gave rise to the extended molecular configuration of PEDOT:PSS, resulting in the improved carrier mobility in the hybrids. Moreover, the energy filtering was induced by such a periodically ordered structure, which blocked the low-energy carriers preferentially and improved the Seebeck coefficient in the hybrids. Therefore, the power factor of the PEDOT:PSS-LDH hybrid was 120-fold higher than that of pristine PEDOT:PSS. These results not only establish an effective method for the construction of periodically ordered TE materials but also address the significance of an ordered structure of molecules in TE materials.

Crystalline Domain Battery Materials

The development of next-generation energy storage materials for secondary batteries relies more and more on the delicate design and tailoring of their local structures and properties. Crystalline domain battery materials (CDBMs) are defined as a family of materials that are hierarchically engineered primarily by bonding selective atoms in certain space groups with short-range order to form nanoscale crystal domains as fundamental constructive and functional units, secondarily by integrating these interactive crystal domains under certain configurations into grains to implement electrochemical synergy, and finally by optimizing grains through nanoengineering toward advanced electrode materials. In CDBMs, adjacent crystal domains can undergo structural co-transformations with noticeable interrelationships, and the overall electrochemical performance is determined not only by the intrinsic structure of each crystal domain (element, bonding, valence, stacking, orientation, etc.) but also by the configuration of crystal domains (size, ratio, interface, distribution, interaction, etc.). Pioneering studies have shown significant enhancement of electrochemical performance by controlling crystal domains, suggesting the prospect of developing novel electrode materials through crystal-domain engineering. However, fundamental understanding and delicate fabrication of this material family, in terms of structural identification, electrochemical structure evolution, reaction mechanism, design and adjustment, and structure-performance relationship, among others, still face great challenges to meet the compelling requirements of high-performance electrode materials for secondary batteries. This Account systematically introduces the structure and electrochemistry of CDBMs. The efficient structural identification of crystal domains, which is still challenging due to their structural complexity, is demonstrated using prototype materials by advanced characterization techniques such as high-energy X-ray diffraction combined with Rietveld refinement and spherical aberration-corrected transmission electron microscopy. Investigations on the structural evolution of CDBMs in electrochemical reactions by ex-situ and in-situ techniques provide insights into reaction scenarios such as how ions migrate in and across crystal domains and how these crystal domains transform synergistically. A crystal-domain reaction mechanism is thus proposed to explain the electrochemistry of these materials. Design principles and adjustment strategies for designated crystal-domain structures including their components, ratios, distributions, and interfaces are deduced from the structural identification, evolution and reaction mechanism. The relationship between crystal-domain structures and electrochemical performance can further be elucidated, inspiring us to explore efficient strategies for optimizing the electrochemical performance, as validated by examples of high-performance batteries using materials with controlled crystal-domain structures. Based on these systematic studies, the trends in the rapid enrichment, deep investigation, and practical application of CDBMs are envisioned to promote continuous studies on this nascent energy storage material family.

Emerging new phase boundary in potassium sodium-niobate based ceramics

A review of the newly emerging “new phase boundary” in potassium sodium niobate-based ceramics with high performance.

“Old dog, new tricks”: the lone pair effect inducing divergent optical responses in lead cyanurates containing π-bonds

The stereochemically active lone pair effect of Pb²⁺ and induced narrower bandgaps were elaborated in Pb₃(HC₃N₃O₃)₂(OH)₂ for the first time.

A long-lifespan, flexible zinc-ion secondary battery using a paper-like cathode from single-atomic layer MnO2 nanosheets

Aqueous zinc ion secondary batteries (ZIBs) have recently attracted considerable attention and global interest due to their low cost, aqueous-based nature and great safety. Unfortunately, the intrinsic properties of poor cycle life, low energy density and uncontrolled dendrite growth during the charge/discharge process for metallic Zn anodes significantly hinder their practical application. In this work, we rationally designed two-dimensional (2D) δ-MnO₂ nanofluidic channels by the ordered restacking of exfoliated MnO₂ single atomic layers, which exhibited a high zinc ion transport coefficient (1.93 × 10^-14 cm² s^-1) owing to their appropriate d-spacing and the negative charge of the inner channel walls. More importantly, we found that Zn dendrite growth was prevented in the as-assembled ZIBs, resulting in superior stability compared with the bulk-MnO₂ sample. Our design sheds light on developing high-performance ZIBs from two-dimensional nanofluidic channels, and this strategy might be applicable to the storage of other metal ions (Mg²⁺, Ca²⁺, Al³⁺, etc.) in next-generation electrochemical energy storage devices.

Ultrafast Zinc-Ion Diffusion Ability Observed in 6.0-Nanometer Spinel Nanodots

Rechargeable aqueous Zn-ion batteries (ZIBs) have recently attracted much attention due to their low cost and superior safety. Unfortunately, their low capacity and poor cycle life still hinder their practical application. Here, we have developed a general synthesis strategy for ultrasmall spinel oxide nanodots (Mn₃O₄, CoMn₂O₄, MnCo₂O_4.5, Co₃O₄, and ZnMn₂O₄) with abundant oxygen vacancies and highly active surface. Among them, 6.0-nanometer-sized Mn₃O₄ nanodots deliver the best Zn-ion storage ability with a high reversible capacity of 386.7 mA h g^-1 at 0.1 A g^-1, excellent rate performance, and a long-term stability of 500 cycles at 0.5 A g^-1. Taking advantage of the highly activated surficial atoms, shortened transfer pathway, and introduction of numerous oxygen vacancies, an ultrahigh Zn²⁺ diffusion coefficient of 2.4 × 10^-10 cm² s^-1 has been detected during the discharge process. This value is more than 2 orders of magnitude higher than that of other spinel oxide nanostructures in previous reports and also the highest one in all of the as-reported ZIB cathode materials to date. Our finding offers promising opportunities for the development of ZIB cathode materials with high energy density, long-term cycling stability, excellent flexibility, and wearability.

Lead-Free Hybrid Metal Halides with a Green-Emissive [MnBr4] Unit as a Selective Turn-On Fluorescent Sensor for Acetone

Organic-inorganic hybrid metal halides with zero-dimensional (0D) structure has emerged as a new class of light-emitting materials. Herein, a new lead-free compound (C₉NH₂₀)₂MnBr₄ has been discovered and a temperature-dependent phase transition has been identified for two phases (space group P2₁/c and C2/c) in which individual [MnBr₄]^2- anions connect with organic cations, (C₉NH₂₀⁺) (1-buty-1-methylpyrrolidinium⁺), forming periodic structure with 0D blocks. A green emission band, peaking at 528 nm with a high photoluminescence quantum efficiency (PLQE) of 81.08%, has been observed at room temperature, which is originated from the ⁴T₁(G) to ⁶A₁ transition of tetrahedrally coordinated Mn²⁺ ions, as also elaborated by density functional theory calculation. Accordingly, a fast, switchable, and highly selective fluorescent sensor platform for different organic solvents based on the luminescence of (C₉NH₂₀)₂MnBr₄ has been developed. We believe that the hybrid metal halides with high PLQE and the exploration of these as a fluorescence sensor will expand the applications scope of bulk 0D materials for future development.