Jing Zhang

Regulating a single substrate and achieving precise control over reaction specificity within a nanozyme is a highly challenging task. Herein, the observed peroxidase (POD)-like and haloperoxidase (HPO)-like activities of rod-shaped CeO₂ are successfully decoupled by examining the facet-dependent activation pathways of H₂O₂, which further sheds light on its facet distribution.

Abstract

CeO₂, particularly in the shape of rod, has recently gained considerable attention for its ability to mimic peroxidase (POD) and haloperoxidase (HPO). However, this multi-enzyme activities unavoidably compete for H₂O₂ affecting its performance in relevant applications. The lack of consensus on facet distribution in rod-shaped CeO₂ further complicates the establishment of structure-activity correlations, presenting challenges for progress in the field. In this study, the HPO-like activity of rod-shaped CeO₂ is successfully enhanced while maintaining its POD-like activity through a facile post-calcination method. By studying the spatial distribution of these two activities and their exclusive H₂O₂ activation pathways on CeO₂ surfaces, this study finds that the increased HPO-like activity originated from the newly exposed (111) surface at the tip of the shortened rods after calcination, while the unchanged POD-like activity is attributed to the retained (110) surface in their lateral area. These findings not only address facet distribution discrepancies commonly reported in the literature for rod-shaped CeO₂ but also offer a simple approach to enhance its antibacterial performance. This work is expected to provide atomic insights into catalytic correlations and guide the design of nanozymes with improved activity and reaction specificity.

This review summarizes the recent advances in the strain engineering of twisted 2D materials, in particular twisted bilayer graphene, toward effectively modifying their Moiré superlattices and tuning electronic structures upon mechanical straining. Through highlighting the potential of diverse straining techniques in modulating various physical properties of twisted bilayer 2D materials, this review aims to provide prospective guidance for the emerging applications of “strain-twistronics” in future devices.

Abstract

The layer-by-layer stacked van der Waals structures (termed vdW hetero/homostructures) offer a new paradigm for materials design—their physical properties can be tuned by the vertical stacking sequence as well as by adding a mechanical twist, stretch, and hydrostatic pressure to the atomic structure. In particular, simple twisting and stacking of two layers of graphene can form a uniform and ordered Moiré superlattice, which can effectively modulate the electrons of graphene layers and lead to the discovery of unconventional superconductivity and strong correlations. However, the twist angle of twisted bilayer graphene (tBLG) is almost unchangeable once the interlayer stacking is determined, while applying mechanical elastic strain provides an alternative way to deeply regulate the electronic structure by controlling the lattice spacing and symmetry. In this review, diverse experimental advances are introduced in straining tBLG by in-plane and out-of-plane modes, followed by the characterizations and calculations toward quantitatively tuning the strain-engineered electronic structures. It is further discussed that the structural relaxation in strained Moiré superlattice and its influence on electronic structures. Finally, the conclusion entails prospects for opportunities of strained twisted 2D materials, discussions on existing challenges, and an outlook on the intriguing emerging field, namely “strain-twistronics”.

Nature, Published online: 15 April 2024; doi:10.1038/s41586-024-07244-z

We introduce strong tailored light-wave-driven time-reversal symmetry breaking in monolayer hexagonal boron nitride, realizing a sub-laser-cycle controllable analogue of the topological model of Haldane and inducing non-resonant valley polarization.

This review highlights the significance of thickness-controlled synthesis in non-Van der Waals self-intercalated Cr2X3 for exploring tunable magnetism in 2D materials. By manipulating the thickness and lattice size during synthesis, researchers have opened new possibilities for tailoring the magnetic properties of these materials. The review systematically discusses the interplay between synthesis methods, crystal structure variations, and resulting magnetism in Cr2X3 thin films. It provides a comprehensive summary of existing studies, shedding light on the importance of synthesis parameters in understanding the magnetic behavior of these materials.

Abstract

In the search for two-dimensional (2D) magnets operating under ambient conditions, quasi-2D non-van der Waals (vdW) materials have attracted considerable research interest over the last five years. In addition to their high Curie temperature (T_C), their superior air stability to that of vdW 2D magnets has made them potential candidates for future room-temperature spintronics applications. Furthermore, recent progress in the thickness-dependent crystal lattice and magnetic properties of non-vdW Cr₂X₃ (X = S, Se, or Te) has brought them to areas that are once set aside for 2D vdW magnets in fundamental research and applications. Despite covalent bonding between magnetic layers, various bottom-up synthesis methods produced thickness-controlled flakes of Cr₂X₃. Moreover, layer-dependent structural and magnetic properties are among the novel research directions in these materials. This review systematically summarizes recent studies on Cr₂X₃ crystal structure, their controllable synthesis, and their respective magnetic properties. A summary of some significant results on thickness-controlled synthesis in Cr₂X₃ and thickness-dependent magnetism in Cr₂Te₃ is presented. Additionally, experimental and theoretical reports are presented to explain interlayer magnetic interaction. The work reveals the interaction between synthesis, structure, and magnetism. Finally, future research directions of new Cr₂X₃-based materials, rich magnetism in Cr₂X₃, and their potential application are discussed.

Perception is crucial for soft robots. This study reviews recent advances in flexible sensing technologies, first introducing various smart soft materials and fabrication techniques, then presenting the flexible sensing modalities and methodologies, followed by exploring the applications of flexible sensors in different fields, finally summarizing the challenges, and providing an outlook for the future.

Abstract

Soft robots have recently attracted increasing interest due to their advantages in durability, flexibility, and deformability, which enable them to adapt to unstructured environments and perform various complex tasks. Perception is crucial for soft robots. To better mimic biological systems, sensors need to be integrated into soft robotic systems to obtain both proprioceptive and external perception for effective usage. This review summarizes the latest advancements in flexible sensing feedback technologies for soft robotic applications. It begins with an introduction to the development of various flexible sensors for soft robots, followed by an in-depth exploration of smart materials and advanced manufacturing methods. A detailed description of flexible sensing modalities and methodologies is also included in the review to illustrate the continuous breakthrough of the technology. In addition, the applications of soft robots based on these advanced sensing technologies are concluded as well. The challenges of flexible sensing technologies for soft robots and promising solutions are finally discussed and analyzed to provide a prospect for future development. By examining the recent advances in intelligent flexible sensing technologies, this review is dedicated to highlighting the potential of soft robotics and motivating innovation within the field.

Altermagnets exhibit momentum-dependent spin-split states providing new opportunities for spin electronic devices. Through temperature-dependent angle-resolved photoemission spectroscopy and disordered local moment calculations, it is demonstrated that the relativistic valence band splitting of the prototypical MnTe altermagnet is of magnetic origin. This is attributed to a novel relativistic spin-splitting phenomenon concurrent with the establishment of the altermagnetic order below the Néel temperature.

Abstract

Altermagnetic (AM) materials exhibit non-relativistic, momentum-dependent spin-split states, ushering in new opportunities for spin electronic devices. While the characteristics of spin-splitting are documented within the framework of the non-relativistic spin group symmetry, there is limited exploration of the inclusion of relativistic symmetry and its impact on the emergence of a novel spin-splitting in the band structure. This study delves into the intricate relativistic electronic structure of an AM material, α−MnTe. Employing temperature-dependent angle-resolved photoelectron spectroscopy across the AM phase transition, the emergence of a relativistic valence band splitting concurrent with the establishment of magnetic order is elucidated. This discovery is validated through disordered local moment calculations, modeling the influence of magnetic order on the electronic structure and confirming the magnetic origin of the observed splitting. The temperature-dependent splitting is ascribed to the advent of relativistic spin-splitting resulting from the strengthening of AM order in α−MnTe as the temperature decreases. This sheds light on a previously unexplored facet of this intriguing material.

Monodispersed and organic amine modified lanthanum hydroxide (OA-La(OH)₃) nanocrystals are synthesized via a nonaqueous wet-chemical method. The OA-La(OH)₃ nanocrystals further expose La adsorption sites and minimize mass transfer barrier by regulating the inner Helmholtz plane (IHP), thereby dramatically increasing its phosphate adsorption capacity, pH adaptability, and anti-interference performance.

Abstract

Advanced phosphate removal is critical for alleviating the serious and widespread aquatic eutrophication, strongly depending on the development of superior adsorption materials to overcome low chemical affinity and sluggish mass transfer at low phosphate concentrations. Herein, the first synthesis of monodispersed and organic amine modified lanthanum hydroxide nanocrystals (OA-La(OH)₃) for advanced phosphate removal by modulating inner Helmholtz plane (IHP), is reported. These OA-La(OH)₃ nanocrystals with positively charged surfaces and abundant exposed La sites exhibit specific affinity toward phosphate, delivering a maximum adsorption capacity of 168 mg P g⁻¹ and a wide pH adaptability from 3.0 to 11.0, as well as a robust anti-interference performance, far surpassing those of documented phosphate removal materials. The superior phosphate removal performance of OA-La(OH)₃ is attributed to its protonated organic amine in IHP, which enhances the electrostatic attraction around the adsorbent-solution interface. Impressively, OA-La(OH)₃ can treat ≈5 000 and ≈3 200 bed volumes of simulated and real phosphate-containing wastewater to below extremely strict standard (0.1 mg L⁻¹) in a fixed-bed adsorption mode, exhibiting great potential for advanced phosphate removal. This study offers a facile modification strategy to improve phosphate removal performance of nanoscale adsorbents, and sheds light on the structure-reactivity relationship of La-based materials.

Although RRAM-based TCAM offers the advantage of reduced cell area, its constrained sensing margin can notably impede parallel data search functionality. This study demonstrates that incorporating nanocavity arrays into CBRAM technology using AAO nanotemplate and integrating with 180 nm CMOS FETs in 2T2R configuration can significantly enhance the sensing margin characteristics favorable for TCAM applications.

Abstract

The development of data-intensive computing methods imposes a significant load on the hardware, requiring progress toward a memory-centric paradigm. Within this context, ternary content-addressable memory (TCAM) can become an essential platform for high-speed in-memory matching applications of large data vectors. Compared to traditional static random-access memory (SRAM) designs, TCAM technology using non-volatile resistive memories (RRAMs) in two-transistor-two-resistor (2T2R) configurations presents a cost-efficient alternative. However, the limited sensing margin between the match and mismatch states in RRAM structures hinders the potential of using memory-based TCAMs for large-scale architectures. Therefore, this study proposes a practical device engineering method to improve the switching response of conductive-bridge memories (CBRAMs) integrated with existing complementary metal-oxide-semiconductor (CMOS) transistor technology. Importantly, this work demonstrates a significant improvement in memory window reaching 1.87 × 10⁷ by incorporating nanocavity arrays and modifying electrode geometry. Consequently, TCAM cells using nanocavity-enhanced CBRAM devices can exhibit a considerable increase in resistance ratio up to 6.17 × 10⁵, thereby closely approximating the sensing metrics observed in SRAM-based TCAMs. The improved sensing capability facilitates the parallel querying of extensive data sets. TCAM array simulations using experimentally verified device models indicate a substantial sensing margin of 65× enabling a parallel search of 2048 bits.

In this work, the vacancy engineering of 2D transition metal chalcogenides (TMCs) is reviewed from two aspects: introduction strategy and application in photocatalysis. Subsequently, the photocatalytic process of 2D TMCs with vacancy engineering is introduced. The synergies between vacancy engineering and TMCs modified by other strategies are discussed. Finally, expectations and suggestions for the development of transition metal chalcogenides are presented.

Abstract

Transition metal chalcogenides (TMCs) are widely used in photocatalytic fields such as hydrogen evolution, nitrogen fixation, and pollutant degradation due to their suitable bandgaps, tunable electronic and optical properties, and strong reducing ability. The unique 2D malleability structure provides a pre-designed platform for customizable structures. The introduction of vacancy engineering makes up for the shortcomings of photocorrosion and limited light response and provides the greatest support for TMCs in terms of kinetics and thermodynamics in photocatalysis. This work reviews the effect of vacancy engineering on photocatalytic performance based on 2D semiconductor TMCs. The characteristics of vacancy introduction strategies are summarized, and the development of photocatalysis of vacancy engineering TMCs materials in energy conversion, degradation, and biological applications is reviewed. The contribution of vacancies in the optical range and charge transfer kinetics is also discussed from the perspective of structure manipulation. Vacancy engineering not only controls and optimizes the structure of the TMCs, but also improves the optical properties, charge transfer, and surface properties. The synergies between TMCs vacancy engineering and atomic doping, other vacancies, and heterojunction composite techniques are discussed in detail, followed by a summary of current trends and potential for expansion.

Nature Communications, Published online: 13 April 2024; doi:10.1038/s41467-024-47479-y

The researchers introduce an all-silicon optical PUF that enhances IoT device security through CMOS-compatible fabrication, showcasing five unique optical responses per pixel for advanced authentication and high information entropy.

To address the paucity of studies into the mechanisms of cell-instructive nanomaterials, single-cell and RNA sequencing, as well as molecular dynamic simulations are used to elucidate the mechanism whereby nanoparticulate MgFe layer double hydroxides (LDH) can either promote the self-renewal or neurogenic differentiation of embryonic stem cells in a time-dependent manner by specific cell membrane receptors (LIFR and PTCH1) activation.

Abstract

Stem cell fate regulation by biomaterials has considerable therapeutic potential; however, the mechanisms whereby biomaterials instruct stem cells for accurate fate regulation still need to be elucidated. Layered double hydroxide (LDH) nanoparticles are widely used for tissue regeneration because of their excellent physicochemical properties and biocompatibility. This study reveals that MgFe-LDH has bidirectional regulatory effects on the differentiation of mouse embryonic stem cells into neural progenitor cells, essentially suppressing cell differentiation on the 1st day and promoting cell differentiation on the 3rd day. Single-cell transcriptome sequencing and simulated computation of structural analysis demonstrate that MgFe-LDH interacts with the membrane receptors leukemia inhibitory factor receptor (LIFR, 15 nm above the cell membrane) and pached1 (PTCH1, 6 nm above the cell membrane) on the 1st and 3rd day of differentiation, respectively. LIFR has more contact with MgFe-LDH than PTCH1 and relatively weaker electrostatic interaction energies (−11010.0 and −9829.3 kJ mol⁻¹ for PTCH1 and LIFR, respectively). These factors determine receptor binding and activation priority, followed by cell fate regulation. The results indicate that MgFe-LDH regulate the activity and fate of stem cells dually, thus creating possibilities for personalized therapy in neurodevelopment and regenerative medicine through an in-depth study of cell membrane receptors.

This article reviews recent breakthroughs in 2D transistor technology, including sub-nanometer gate length, ultra-low resistance contact, atomically thin dielectric, novel architecture form (2D fin field-effect transistor), and direct integration with Si complementary metal-oxide-semiconductor. The high-performance 2D InSe transistor approaches theoretical limit. The remaining challenges and exciting future prospects of 2D transistors for extending Moore's Law are also highlighted.

Abstract

Since Si-based Moore's law is physically limited, 2D semiconductors are proposed as successors to continue shrinking the transistor size for more Moore electronics. However, limited by experimental technology bottlenecks, the theoretical predicted superiorities of the 2D transistors over the state-of-the-art Si transistors have been lacking concrete evidence for a decade. In this review, recent exciting experimental breakthroughs for 2D transistors are presented, including gate length miniaturization to a sub-1 nm limit, electrode contact optimization to the resistance quantum limit, high-quality dielectric fabrication with an equivalent oxide thickness to sub-0.5 nm, novel architecture form (2D fin field-effect transistor), and back-end-of-line integration of directly grown 2D materials on Si complementary metal-oxide-semiconductor circuits. Remarkably, an ultrashort channel, Ohmic contact, ballistic transport, and ultrathin dielectric layer are simultaneously satisfied in the 2D InSe transistor, and device performances approaching the theoretical limit are observed. The measured key figures of merit of the ideal 2D InSe transistor are comparable to or even surpass those of the Si transistors. Finally, the challenges and outlook on more Moore electronics based on 2D transistors are highlighted.

An ideally adaptive cellular scaffold is developed by decorating a fluid interface with phospholipid membranes. In contrast to conventional solid or hydrogel scaffolds, cell adhesion behaviors thereon follow an adaptive wetting regime with surprisingly high mechanical work, which highlights an analogy of cell adhesion behaviors and droplet wetting on surfaces with a low Young's modulus.

Abstract

Living cells actively interact biochemically and mechanically with the surrounding extracellular matrices (ECMs) and undergo dramatic morphological and dimensional transitions, concomitantly remodeling ECMs. However, there is no suitable method to quantitatively discuss the contribution of mechanical interactions in such mutually adaptive processes. Herein, a highly deformable “living” cellular scaffold is developed to evaluate overall mechanical energy transfer between cell and ECMs. It is based on the water–perfluorocarbon interface decorated with phospholipids bearing a cell-adhesive ligand and fluorescent tag. The bioinert nature of the phospholipid membranes prevents the formation of solid-like protein nanofilms at the fluid interface, enabling to visualize and quantify cellular mechanical work against the ultimately adaptive model ECM. A new cellular wetting regime is identified, wherein interface deformation proceeds to cell flattening, followed by its eventual restoration. The cellular mechanical work during this adaptive wetting process is one order of magnitude higher than those reported with conventional elastic platforms. The behavior of viscous liquid drops at the air–water interface can simulate cellular adaptive wetting, suggesting that overall viscoelasticity of the cell body predominates the emergent wetting regime and regulates mechanical output. Cellular-force-driven high-energy states on the adaptive platform can be useful for cell fate manipulation.

An ultrathin, high-performance transistor layer suitable for multilayer stacking is developed for monolithic 3D integration, utilizing directly grown nanocrystalline graphene and dry-transferred MoS₂ film. This device structure retains the advantages of a dangling bond-free, ultrathin channel and low contact resistivity, making it a significant enabler for high-density 3D circuit technology.

Abstract

The potential of monolithic 3D integration technology is largely dependent on the enhancement of interconnect characteristics which can lead to thinner stacks, better heat dissipation, and reduced signal delays. Carbon materials such as graphene, characterized by sp2 hybridized carbons, are promising candidates for future interconnects due to their exceptional electrical, thermal conductivity and resistance to electromigration. However, a significant challenge lies in achieving low contact resistance between extremely thin semiconductor channels and graphitic materials. To address this issue, an innovative wafer-scale synthesis approach is proposed that enables low contact resistance between dry-transferred 2D semiconductors and the as-grown nanocrystalline graphitic interconnects. A hybrid graphitic interconnect with metal doping reduces the sheet resistance by 84% compared to an equivalent thickness metal film. Furthermore, the introduction of a buried graphitic contact results in a contact resistance that is 17 times lower than that of bulk metal contacts (>40 nm). Transistors with this optimal structure are used to successfully demonstrate a simple logic function. The thickness of active layer is maintained within sub-7 nm range, encompassing both channels and contacts. The ultrathin transistor and interconnect stack developed here, characterized by a readily etchable interlayer and low parasitic resistance, leads to heterogeneous integration of future 3D integrated circuits (ICs).

A comprehensive scheme combining an autoencoding regularized adversarial neural network and feature-adaptive variational active learning algorithm for screening low-contact electrodes for 2D semiconductor transistors in a limited data scenario is proposed. This scheme outperforms classical models and the state-of-the-art boosting techniques trained using limited datasets, as well as models trained using randomly selected data.

Abstract

Low-barrier and high-injection electrodes are crucial for high-performance (HP) 2D semiconductor devices. Conventional trial-and-error methodologies for electrode material screening are impractical because of their low efficiency and arbitrary specificity. Although machine learning has emerged as a promising alternative to tackle this problem, its practical application in semiconductor devices is hindered by its substantial data requirements. In this paper, a comprehensive scheme combining an autoencoding regularized adversarial neural network and a feature-adaptive variational active learning algorithm for screening low-contact electrode materials for 2D semiconductor transistors with limited data is proposed. The proposed scheme exhibits exceptional performance by training with only 15% of the total data points, where the mean square errors are 0.17 and 0.27 eV for the vertical and lateral Schottky barrier, respectively, and 2.88% for tunneling probability. Further, it exhibits an optimal predictive performance for 100 randomly sampled training datasets, reveals the underlying physical insight based on the identified features, and realizes continual improvement by employing detailed density-of-states descriptors. Finally, the empirical evaluations of the transport characteristics are conducted and verified by constructing MOSFET devices. These findings demonstrate the considerable potential of machine-learning techniques for screening high-efficiency electrode materials and constructing HP 2D semiconductor devices.

A nondestructive crystallographic scanning technique for 2D materials is developed, leveraging sticky-note-like van der Waals assembling–disassembling. This method visualizes the detailed crystallography of each grain within polycrystalline graphene using a single-atom-thick single-crystalline graphene and Raman signals varying dependent on interlayer twist angles. It facilitates a deeper understanding of 2D material properties, promoting further material engineering and optimization breakthroughs.

Abstract

Crystallographic characteristics, including grain boundaries and crystallographic orientation of each grain, are crucial in defining the properties of two-dimensional materials (2DMs). To date, local microstructure analysis of 2DMs, which requires destructive and complex processes, is primarily used to identify unknown 2DM specimens, hindering the subsequent use of characterized samples. Here, a nondestructive large-area 2D crystallographic analytical method through sticky-note-like van der Waals (vdW) assembling–disassembling is presented. By the vdW assembling of veiled polycrystalline graphene (PCG) with a single-atom-thick single-crystalline graphene filter (SCG-filter), detailed crystallographic information of each grain in PCGs is visualized through a 2D Raman signal scan, which relies on the interlayer twist angle. The scanned PCGs are seamlessly separated from the SCG-filter using vdW disassembling, preserving their original condition. The remaining SCG-filter is then reused for additional crystallographic scans of other PCGs. It is believed that the methods can pave the way for advances in the crystallographic analysis of single-atom-thick materials, offering huge implications for the applications of 2DMs.

Nature Synthesis, Published online: 12 April 2024; doi:10.1038/s44160-024-00523-7

Metal vacancies capable of generating magnetism can be created in 2D semiconductors by atomic-scale etching induced by electron-beam irradiation.

This study introduces a novel chelating strategy that utilizes metal manganese ions and multidentate ligands, markedly improving the structural stability and emission efficiency of CsPbBr₃ NPLs. The resultant NPLs films demonstrate an impressive PLQY of 66%, showcasing remarkable air stability with consistent blue emission for up to five days.

Abstract

Quantum-confined perovskite CsPbBr₃ Nanoplatelets (NPLs) have recently emerged as promising blue-emitting materials for perovskite light-emitting diodes (PeLEDs). Yet, their susceptibility to optical instability in solid films under ambient conditions poses a significant hindrance. This study introduces a novel chelating strategy that utilizes metal manganese ions and multidentate ligands, markedly improving the structural stability, and emission efficiency of NPLs. The approach involves adding Diethylenetriaminepentaacetic acid (DTPA) to the perovskite precursor solution, which allows for strong coordination to surface [PbBr₆]⁴⁻ octahedrons via its multiple chelation sites. Ensuing metal manganese ion integration during the purification phase addresses Pb²⁺ and Br⁻ site vacancies, culminating in near-perfect octahedral structures with significantly fewer vacancies. These metal manganese ions are then further immobilized on the NPLs surface by the chelating effect of unbound DTPA functional groups. The resultant CsPbBr₃ NPLs films demonstrate an impressive PLQY of 66%, showcasing remarkable air stability with consistent blue emission for up to 5 days. The CsPbBr₃ NPLs-based PeLEDs show electroluminescence at 460 nm with a current efficiency of 1.07 cd A⁻¹ and a maximum luminance of 220 cd m⁻². The proposed chelating strategy positions perovskite NPLs as an extremely promising prospect in future applications of high-definition displays and high-quality lighting.

Microencapsulated mixtures of fluorescent dyes in organic phase change materials are used to generate composite-based thermoresponsive fluorescent pixels, which undergo multistep color and/or intensity emission changes upon temperature variation. Arrays of these pixels are exploited for high-security 3D information encryption and 4D data storage.

Abstract

Luminescent materials are emerging promising tools for digital data encoding due to their reduced cost, facile reading, robustness, and durability. For this, the use of fluorescent systems that combine multicolor emission with sensitivity to external stimuli will be highly desirable, as they can offer rewritable data encoding together with enhanced encryption security and storage density. Herein a novel strategy is pioneered to reach this goal, which exploits the temperature-responsive emission properties of the mixtures of regular fluorophores with simple organic phase change materials (PCMs) such as paraffins. By preparing a diversity of microcapsules of these mixtures comprising different dyes and PCMs, thermosensitive fluorescent pixels can be prepared in a low-cost, straightforward, and scalable manner that exhibits multicolor dynamic emission behavior. These features are capitalized to fabricate pixel arrays that perform two advanced digital encoding operations: high-security 3D information encryption, and 4D data storage.

A rhombic 2D conjugated metal–organic framework (2D c-MOF) Cu-TBA (TBA = octahydroxyltetrabenzoanthracene) is employed as the cathode material for high-performance sodium-ion batteries. Cu-TBA outperforms its hexagonal counterpart, Cu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxyltriphenylene), demonstrating superior reversible capacity (153.6 mAh g⁻¹ at 50 mA g⁻¹) and outstanding cyclability with minimal capacity decay even after 3000 cycles at 1 A g⁻¹.

Abstract

2D conjugated metal–organic frameworks (2D c-MOFs) have garnered significant attention as promising electroactive materials for energy storage. However, their further applications are hindered by low capacity, limited cycling life, and underutilization of the active sites. Herein, Cu-TBA (TBA = octahydroxyltetrabenzoanthracene) with large conjugation units (narrow energy gap) and a unique rhombus topology is introduced as the cathode material for sodium-ion batteries (SIBs). Notably, Cu-TBA with a rhombus topology exhibits a high specific surface area (613 m² g⁻¹) and metallic band structure. Additionally, Cu-TBA outperforms its hexagonal counterpart, Cu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxyltriphenylene), demonstrating superior reversible capacity (153.6 mAh g⁻¹ at 50 mA g⁻¹) and outstanding cyclability with minimal capacity decay even after 3000 cycles at 1 A g⁻¹. This work elucidates a new strategy to enhance the electrochemical performance of 2D c-MOFs cathode materials by narrowing the energy gap of organic linkers, effectively expanding the utilization of 2D c-MOFs for SIBs.

This perspective addresses some of the key lessons learned in nanosafety research during the past 15 years with an emphasis on nano-bio interactions (interactions of nanomaterials with biological systems), in particular, the bio-corona and eco-corona.

Abstract

Engineered nanomaterials offer numerous benefits to society ranging from environmental remediation to biomedical applications such as drug or vaccine delivery as well as clean and cost-effective energy production and storage, and the promise of a more sustainable way of life. However, as nanomaterials of increasing sophistication enter the market, close attention to potential adverse effects on human health and the environment is needed. Here a critical perspective on nanotoxicological research is provided; the authors argue that it is time to leverage the knowledge regarding the biological interactions of nanomaterials to achieve a more comprehensive understanding of the human health and environmental impacts of these materials. Moreover, it is posited that nanomaterials behave like biological entities and that they should be regulated as such.

Nature, Published online: 10 April 2024; doi:10.1038/d41586-024-01006-7

An innovative solid-state lithiation strategy allows the exfoliation of layered transition-metal tellurides into nanosheets in an unprecedentedly short time, without sacrificing their quality. The observation of physical phenomena typically seen in highly crystalline TMT nanosheets opens the way to their use in applications such as batteries and micro-supercapacitors.

Nature, Published online: 10 April 2024; doi:10.1038/s41586-024-07175-9

We demonstrate the emergence of magnetism induced by a terahertz electric field in SrTiO3.

The synergistic effect between lanthanide ions and perovskite matrix for electroluminescent devices is studied. The luminescent mechanism and synthesis methods for lanthanide-ion-doped perovskite (LIDP) nanocrystals are summarized and current challenges and potential strategies in LIDP-based electroluminescent devices are analyzed. This discussion provides guidance for future LIDP-based device development, drawing insights from organic/perovskite light-emitting diodes to accelerate progress.

Abstract

Lanthanide ions doped in perovskite (LIDP) nanocrystals (NCs) provide an effective way to utilize the emission of lanthanide metals in a solution-processable way, combining the theoretical photoluminance quantum yield (PLQY) of ≈200%. To utilize advantages, LIDP-NCs have inspired studies exploring the fundamental physics of energy transfer, including the up-conversion or down-conversion process, and the optoelectronic applications of solar cells and white light-emitting didoes. This review broadens the scope of LIDP nanocrystal matrix semiconductors in electroluminescence devices in the near-infrared (NIR) range (>900 nm). A research is summarized on the synergistic effect of lanthanide ions and perovskite matrix in the near-infrared region, and discuss from the perspective of fabrication of lanthanide-based electroluminescent devices using perovskite materials as the matrix. The multiple optical transitions, bandgap tunability, and quantum-cutting effect to provide a tutorial on understanding LIDP-NCs are started. The details of synthesizing LIDP materials and aim to lay the foundation for preparing NIR electroluminescent devices with high efficiency and application value are then illustrated. The scientific issues that limit the performance of LIDP NCs-based electroluminescent devices and discuss the potential strategies for the future development of LIDP material are focused on.

In this work, the controllable synthesis of 2D Fe_1+yTe nanoflakes are realized with tunable Fe content by CVD method. Among them, the Fe_1.13±0.06Te crystal exhibits a sharp superconducting transition (ΔT _c = 1 K) at B = 0 T, and the transition temperature T _c is measured to be 10.2 K at B = 12 T. Additionally, the high-Fe content Fe_1.43±0.07Te crystal shows a relative broad superconducting transition (ΔT _c = 2.6 K) at B = 0 T, and T _c is suppressed to 3.8 K at B = 12 T, which is related to the 3D-to-2D vortex liquid transition. This research will pave the way for understanding the intrinsic mechanisms of high-temperature superconductivity.

Abstract

2D materials provide an ideal platform to explore novel superconducting behavior including Ising superconductivity, topological superconductivity and Majorana bound states in different 2D stoichiometric Ta-, Nb-, and Fe-based crystals. However, tuning the element content in 2D compounds for regulating their superconductivity has not been realized. In this work, the synthesis of high quality Fe_1+yTe with tunable Fe content by chemical vapor deposition (CVD) is reported. The quality and composition of Fe_1+yTe are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM). The superconducting behavior of Fe_1+yTe crystals with varying Fe contents is observed. The superconducting transition of selected Fe_1.13±0.06Te sample is sharp (ΔT _c = 1 K), while Fe_1.43±0.07Te with a high-Fe content shows a relative broad superconducting transition (ΔT _c = 2.6 K) at zero magnetic field. Significantly, the conspicuous vortex flow and a transition from a 3D vortex liquid state to a 2D vortex liquid state is observed in Fe_1.43±0.07Te sample. This work highlights the tunability of the superconducting properties of Fe_1+yTe and sheds light on the vortex dynamics in Fe-based superconductors, which facilitates them to understand the intrinsic mechanisms of high-temperature superconductivity.

The synthesis of Bi_2–xSb_xSe₃ nanoflakes on a mica substrate with a thickness tunable to 2 nm through a BiOCl-aidedchemical vapor deposition (CVD) process is reported. Electronic transportstudies reveal that the Field-effect transistor (FET) devices built from Bi_2–xSb_xSe₃ exhibit ambipolar properties, with a carrier density down to 1.6 × 1012 cm^–2 and field-effect mobility and Hall mobility up to 3411 and 6462 cm²V^–1 s^–1, respectively.

Abstract

Highcarrier concentration and low mobility in Bi₂Se₃ hide thetopological surface states (TSS). In the 2D ternary topological insulator (TI) Bi_2–xSb_xSe₃,compensatory Sb doping regulates the carrier concentration and mobility withambipolar performance, together with the ultrathin thickness; these factorsmake the TSS in the 2D ternary TI Bi_2–xSb_xSe₃ more observable. Here, a chemical vapor deposition (CVD) method is provided for synthesizing ultrathin Sb-doped Bi₂Se₃ nanoplates with dimensions of 2–126 nm in thickness, 3–100 µm in lateral size, and an average Sb doping ranging from 0.15 ≤ x ≤ 0.75. Bi_2–xSb_xSe₃ field effect transistors and Hall devices are manufactured to determine the carrier concentration and mobility of the obtained Bi_2–xSb_xSe₃ nanoplates. These findings demonstrate that the 2D carrier concentration for Bi_2–xSb_xSe₃ nanoplates can decrease up to 1.6 × 10¹² cm^–2. Furthermore, field-effect mobility and Hall mobility of up to 3411 cm² V^–1s^–1 and 6462 cm² V^–1 s^–1, respectively, are realized. A strong ambipolar field effect is found in low-carrier-density Bi_2–xSb_xSe₃ nanoplates, proving that these nanostructures may be freely controlled in terms of carrier type and concentration. The synthesis of high-quality Bi_2–xSb_xSe₃ nanoplates with low-carrier concentration and high-mobility provides a platform for investigating TI characteristics more clearly.

Here, an effective approach is proposed to design deep-blue thermally activated delayed fluorescence molecules based on hybrid long- and short-range charge-transfer by incorporating multiple donor moieties into organoboron multiple resonance acceptors. The resulting molecule exhibits deep-blue emission, narrow spectra, and high reverse intersystem crossing rate. The organic light-emitting diode fabricated with the designed molecule records maximum external quantum efficiency of 22.8% with the Commission Internationale de l’Éclairage coordinates of (0.163, 0.046).

Abstract

Organic luminescent materials that exhibit thermally activated delayed fluorescence (TADF) can convert non-emissive triplet excitons into emissive singlet states through a reverse intersystem crossing (RISC) process. Therefore, they have tremendous potential for applications in organic light-emitting diodes (OLEDs). However, with the development of ultra-high definition 4K/8K display technologies, designing efficient deep-blue TADF materials to achieve the Commission Internationale de l’Éclairage (CIE) coordinates fulfilling BT.2020 remains a significant challenge. Here, an effective approach is proposed to design deep-blue TADF molecules based on hybrid long- and short-range charge-transfer by incorporation of multiple donor moieties into organoboron multiple resonance acceptors. The resulting TADF molecule exhibits deep-blue emission at 414 nm with a full width at half maximum (FWHM) of 29 nm, together with a thousand-fold increase in RISC rate. OLEDs based on the champion material achieve a record maximum external quantum efficiency (EQE) of 22.8% with CIE coordinates of (0.163, 0.046), approaching the coordinates of the BT.2020 blue standard. Moreover, TADF-assisted fluorescence devices employing the designed material as a sensitizer exhibit an exceptional EQE of 33.1%. This work thus provides a blueprint for future development of efficient deep-blue TADF emitters, representing an important milestone towards meeting the blue color gamut standard of BT.2020.

In this study, a novel modular encapsulation strategy that provides high enthalpy thermal dissipation for mitigating the overheat of stretchable electronics is proposed. The hydrogel-based encapsulation can provide thermal protection through water evaporation and automatically recover its functions by absorbing moisture. This method  provides a universal pathway for improving the thermal stability of stretchable electronics in practical applications.

Abstract

The practical application of flexible and stretchable electronics is significantly influenced by their thermal and chemical stability. Elastomer substrates and encapsulation, due to their soft polymer chains and high surface-area-to-volume ratio, are particularly susceptible to high temperatures and flame. Excessive heat poses a severe threat of damage and decomposition to these elastomers. By leveraging water as a high enthalpy dissipating agent, here, a hydrogel encapsulation strategy is proposed to enhance the flame retardancy and thermal stability of stretchable electronics. The hydrogel-based encapsulation provides thermal protection against flames for more than 10 s through the evaporation of water. Further, the stretchability and functions automatically recover by absorbing air moisture. The incorporation of hydrogel encapsulation enables stretchable electronics to maintain their functions and perform complex tasks, such as fire saving in soft robotics and integrated electronics sensing. With high enthalpy heat dissipation, encapsulated soft electronic devices are effectively shielded and retain their full functionality. This strategy offers a universal method for flame retardant encapsulation of stretchable electronic devices.