Jiuxiang Dai

Nature, Published online: 29 May 2024; doi:10.1038/s41586-024-07371-7

Nature, Published online: 29 May 2024; doi:10.1038/s41586-024-07454-5

Nature, Published online: 29 May 2024; doi:10.1038/s41586-024-07438-5

A new strategy of NH₄ ⁺ pre-intercalation and Mo doping is proposed to synergistically modulate the nanostructural and electronic properties of VS₂. It shows that the expansion of interlayer spacing by NH₄ ⁺ pre-intercalation along with double-defects constructing and electronic structure regulation by Mo-doping provide new ion transport channels to accelerate Na⁺ kinetics, resulting in significantly enhanced Na⁺ storage capability.

Abstract

Sodium-ion hybrid capacitors (SIHCs) have attracted much attention due to integrating the high energy density of battery and high out power of supercapacitors. However, rapid Na⁺ diffusion kinetics in cathode is counterbalanced with sluggish anode, hindering the further advancement and commercialization of SIHCs. Here, aiming at conversion-type metal sulfide anode, taking typical VS₂ as an example, a comprehensive regulation of nanostructure and electronic properties through NH₄ ⁺ pre-intercalation and Mo-doping VS₂ (Mo-NVS₂) is reported. It is demonstrated that NH₄ ⁺ pre-intercalation can enlarge the interplanar spacing and Mo-doping can induce interlayer defects and sulfur vacancies that are favorable to construct new ion transport channels, thus resulting in significantly enhanced Na⁺ diffusion kinetics and pseudocapacitance. Density functional theory calculations further reveal that the introduction of NH₄ ⁺ and Mo-doping enhances the electronic conductivity, lowers the diffusion energy barrier of Na⁺, and produces stronger d-p hybridization to promote conversion kinetics of Na⁺ intercalation intermediates. Consequently, Mo-NVS₂ delivers a record-high reversible capacity of 453 mAh g⁻¹ at 3 A g⁻¹ and an ultra-stable cycle life of over 20 000 cycles. The assembled SIHCs achieve impressive energy density/power density of 98 Wh kg⁻¹/11.84 kW kg⁻¹, ultralong cycling life of over 15000 cycles, and very low self-discharge rate (0.84 mV h⁻¹).

Light: Science & Applications, Published online: 31 May 2024; doi:10.1038/s41377-024-01481-7

This article reviews the development of quantum dots (QDs), then systematically introduces the design and synthesis of colloidal QDs, fabrication and optimization of quantum dot light-emitting diodes (QLEDs), as well as the recent performance progress of QLED devices. In addition, the research advancement and future trends of QLED display technology are summarized and prospected.

Abstract

Colloidal quantum dots (QDs), as a class of 0D semiconductor materials, have generated widespread interest due to their adjustable band gap, exceptional color purity, near-unity quantum yield, and solution-processability. With decades of dedicated research, the potential applications of quantum dots have garnered significant recognition in both the academic and industrial communities. Furthermore, the related quantum dot light-emitting diodes (QLEDs) stand out as one of the most promising contenders for the next-generation display technologies. Although QD-based color conversion films are applied to improve the color gamut of existing display technologies, the broader application of QLED devices remains in its nascent stages, facing many challenges on the path to commercialization. This review encapsulates the historical discovery and subsequent research advancements in QD materials and their synthesis methods. Additionally, the working mechanisms and architectural design of QLED prototype devices are discussed. Furthermore, the review surveys the latest advancements of QLED devices within the display industry. The narrative concludes with an examination of the challenges and perspectives of QLED technology in the foreseeable future.

A novel family of cell manipulators is presented, which are deformable by optical tweezers and rely on their elasticity to hold single, nonadherent cells. The structures, prepared with multiphoton polymerization, provide high spatial and temporal control over the manipulation of the cells enabling single cell movement with 6° of freedom and cell–cell interactions.

Abstract

Precisely controlled manipulation of nonadherent single cells is often a pre-requisite for their detailed investigation. Optical trapping provides a versatile means for positioning cells with submicrometer precision or measuring forces with femto-Newton resolution. A variant of the technique, called indirect optical trapping, enables single-cell manipulation with no photodamage and superior spatial control and stability by relying on optically trapped microtools biochemically bound to the cell. High-resolution 3D lithography enables to prepare such cell manipulators with any predefined shape, greatly extending the number of achievable manipulation tasks. Here, it is presented for the first time a novel family of cell manipulators that are deformable by optical tweezers and rely on their elasticity to hold cells. This provides a more straightforward approach to indirect optical trapping by avoiding biochemical functionalization for cell attachment, and consequently by enabling the manipulated cells to be released at any time. Using the photoresist Ormocomp, the deformations achievable with optical forces in the tens of pN range and present three modes of single-cell manipulation as examples to showcase the possible applications such soft microrobotic tools can offer are characterized. The applications describe here include cell collection, 3D cell imaging, and spatially and temporally controlled cell–cell interaction.

2D metal phosphorous trichalcogenides (MPCh₃) have attracted considerable attention due to their distinct physical and chemical properties. This review summarizes the progress in 2D MPCh₃ nanomaterials for energy conversion and storage applications, including rechargeable batteries, supercapacitors, photocatalysis, electrocatalysis, and desalination, offering insights for the further development of novel 2D materials in the field of energy applications.

Abstract

2D metal phosphorous trichalcogenides (MPCh₃) have attracted considerable attention in sustainable energy storage and conversion due to their distinct physical and chemical characteristics, such as adjustable energy bandgap, significant specific surface area, and abundant active sites. However, research on 2D MPCh₃ primarily focuses on electrocatalysis, and understanding its energy conversion and storage mechanisms remains incomplete. This review comprehensively summarizes recent advancements in energy storage and conversion using 2D MPCh₃-based materials of various structures. It begins with a discussion of the distinctive properties and preparation techniques of 2D MPCh₃, followed by a focus on the rational design and development of these materials for diverse energy-related applications, including rechargeable batteries, supercapacitors, electrocatalysis, photocatalysis, and desalination. Finally, it outlines the key challenges and prospects for future research on 2D MPCh₃ materials.

The ferroelectric properties and polarization switching of Hf_0.5Zr_0.5O₂ thin films annealed at various temperatures are systematically investigated. Piezoresponse force microscopy, as well as switching current measurements, revealed non-monotonic changes in the polarization switching speed concerning the annealing temperature. These variations are attributed to differences in the ferroelectric-domain nucleation process induced by different defect levels in the films.

Abstract

Recently, HfO₂-based ferroelectric thin films have attracted widespread interest in developing next-generation nonvolatile memories. To form a metastable ferroelectric orthorhombic phase in HfO₂, a post-annealing process is typically necessary. However, the microscopic mechanism underlying the effect of annealing temperature on ferroelectric domain nucleation and growth is still obscure, despite its importance in optimizing the operation speed of HfO₂-based devices. In this study, the ferroelectric properties and polarization switching of Hf_0.5Zr_0.5O₂ thin films annealed at different temperatures (550–700 °C) are systematically investigated. Evidently, the crystal structure, remnant polarization, and dielectric constant monotonically change with annealing temperature. However, microscopic piezoresponse force microscopy images as well as macroscopic switching current measurements reveal non-monotonic changes in the polarization switching speed with annealing temperature. This intriguing behavior is ascribed to the difference in the ferroelectric-domain nucleation process induced by the amount of oxygen vacancies in the Hf_0.5Zr_0.5O₂ thin films annealed at different temperatures. This work demonstrates that controlling the defect concentration of ferroelectric HfO₂ by tuning the post-annealing process is critical for optimizing device performance, particularly polarization switching speed.

An electronic transformation in the LaCoO₃ monolayer from the conventional mixed high-spin/low-spin state to an unprecedented fully high-spin state is successfully achieved by constructing SrIrO₃/LaCoO₃ superlattices. This emergent fully high-spin species exhibits strong 2D ferromagnetism with a Curie temperature exceeding 100 K. Additionally, interfacial Ir/Co hybridization drives orbital reconstruction with polarization beyond standard crystal field expectations.

Abstract

Perovskite LaCoO₃ is a subject of extensive and ongoing investigation due to the delicate competition between high-spin (HS) and low-spin (LS) states of Co³⁺. On the other hand, their indistinct free energy boundary poses a significant challenge to annihilate the magnetically/electrically inert LS Co³⁺ for yielding fully HS state. Here, electronic transformation from the conventional isovalent mixed HS/LS state (La[CoHS3+,CoLS3+]O3${\mathrm{La}}[ {{\mathrm{Co}}_{HS}^{3 + },{\mathrm{Co}}_{LS}^{3 + }} ]{{{\mathrm{O}}}_3}$) into an unprecedented aliovalent fully HS state (La[CoHS3+,CoHS2+]O3${\mathrm{La}}[{\mathrm{Co}}_{HS}^{3 + },{\mathrm{Co}}_{HS}^{2 + }]{{{\mathrm{O}}}_3}$) is demonstrated in monolayer LaCoO₃ confined by 5d SrIrO₃ slabs via atomically constructing SrIrO₃/LaCoO₃ superlattices. Excitingly, this emergent fully HS La[CoHS3+,CoHS2+]O3${\mathrm{La}}[ {{\mathrm{Co}}_{HS}^{3 + },{\mathrm{Co}}_{HS}^{2 + }} ]{{{\mathrm{O}}}_3}$ monolayer exhibits not only remarkable 2D ferromagnetism beyond the Mermin–Wagner restriction, but also larger magnetization (≈1.8µ_B/Co) and higher Curie temperature (above 100 K) than that of conventional La[CoHS3+,CoLS3+]O3${\mathrm{La}}[ {{\mathrm{Co}}_{HS}^{3 + },{\mathrm{Co}}_{LS}^{3 + }} ]{{{\mathrm{O}}}_3}$ thick film and any previously reported oxide-based monolayer ferromagnets. Furthermore, Ir/Co hybridization driven orbital reconstruction with polarization beyond standard crystal field expectations is observed, which is supported by DFT calculations. The findings not only expand the electronic phase domains of LCO into fully HS state, but also provide a fresh platform for investigating the 2D magnetic physics under strongly spin-orbit coupled regime and developing new 2D spintronic devices.

A high-performance LCO cathode is developed with a gradient disordering structure design, enabling it to reach the capacity limit (up to 93% of Li utilization) while maintaining high cyclability and rate capability. Comprehensive analysis reveals this innovative structure fundamentally addresses the anisotropic lattice strain issue and exhibits remarkable fatigue resistance, even under harsh operating voltages.

Abstract

Pushing intercalation-type cathode materials to their theoretical capacity often suffers from fragile Li-deficient frameworks and severe lattice strain, leading to mechanical failure issues within the crystal structure and fast capacity fading. This is particularly pronounced in layered oxide cathodes because the intrinsic nature of their structures is susceptible to structural degradation with excessive Li extraction, which remains unsolved yet despite attempts involving elemental doping and surface coating strategies. Herein, a mechanochemical strengthening strategy is developed through a gradient disordering structure to address these challenges and push the LiCoO₂ (LCO) layered cathode approaching the capacity limit (256 mAh g⁻¹, up to 93% of Li utilization). This innovative approach also demonstrates exceptional cyclability and rate capability, as validated in practical Ah-level pouch full cells, surpassing the current performance benchmarks. Comprehensive characterizations with multiscale X-ray, electron diffraction, and imaging techniques unveil that the gradient disordering structure notably diminishes the anisotropic lattice strain and exhibits high fatigue resistance, even under extreme delithiation states and harsh operating voltages. Consequently, this designed LCO cathode impedes the growth and propagation of particle cracks, and mitigates irreversible phase transitions. This work sheds light on promising directions toward next-generation high-energy-density battery materials through structural chemistry design.

Nature Reviews Materials, Published online: 28 May 2024; doi:10.1038/s41578-024-00688-9

Author(s): Cheong-Eung Ahn, Kyung-Hwan Jin, Young-Jae Choi, Jae Whan Park, Han Woong Yeom, Ara Go, Yong Baek Kim, and Gil Young Cho

1T-transition metal dichalcogenides (TMDs) have been an exciting platform for exploring the intertwinement of charge density waves and strong correlation phenomena. While the David star structure has been conventionally considered as the underlying charge order in the literature, recent scanning tun…

[Phys. Rev. Lett. 132, 226401] Published Tue May 28, 2024

2D t-InTe crystal is developed to realize broadband-response and high-anisotropy polarized photodetection. Originating from its narrow band gap (≈1.28 eV) and low-symmetry crystal structure, 2D t-InTe-based photodetector demonstrates a UV–vis–NIR broadband photoresponse with excellent near-infrared photodetection performance, and strong anisotropic photoresponsivity with an exceptional anisotropy factor of 1.81@808 nm, confirming its promise for high-performance polarized optoelectronics.

Abstract

Polarization-sensitive photodetection grounded on low-symmetry 2D materials has immense potential in improving detection accuracy, realizing intelligent detection, and enabling multidimensional visual perception, which has promising application prospects in bio-identification, optical communications, near-infrared imaging, radar, military, and security. However, the majority of the reported polarized photodetection are limited by UV–vis response range and low anisotropic photoresponsivity factor, limiting the achievement of high-performance anisotropic photodetection. Herein, 2D t-InTe crystal is introduced into anisotropic systems and developed to realize broadband-response and high-anisotropy-ratio polarized photodetection. Stemming from its narrow band gap and intrinsic low-symmetry lattice characteristic, 2D t-InTe-based photodetector exhibits a UV–vis–NIR broadband photoresponse and significant photoresponsivity anisotropy behavior, with an exceptional in-plane anisotropic factor of 1.81@808 nm laser, surpassing the performance of most reported 2D counterparts. This work expounds the anisotropic structure-activity relationship of 2D t-InTe crystal, and identifies 2D t-InTe as a prospective candidate for high-performance polarization-sensitive optoelectronics, laying the foundation for future multifunctional device applications.

A carbon-covalent amorphous niobium oxide via formation of Nb─O─C bonds is prepared, which can effectively prevent phase transition and maintains its structure during cycling. Conversely, crystalline carbon-coated Nb₂O₅ and pure amorphous Nb₂O₅ all experience an irreversible phase transition, which is detrimental to structural stability. The a-Nb₂O₅-C exhibits a high reversible capacity, ultrafast lithium storage and long cycling stability as a LIBs anode.

Abstract

Niobium oxides are potential anode materials for ultrafast and safe lithium-ion batteries due to their high ionic conductivity and relatively high operation voltage. However, the electrochemically induced phase transformations that involve multi-electron redox reactions in a wide voltage window cause rapid capacity degradation and poor rate capability. Here, a novel carbon-covalent amorphous niobium oxide anode is reported to greatly suppress the phase transition during cycling via formation of strong Nb─O─C bonds, achieving high-capacity, fast-charge and long-duration lithium storage. This amorphous structure and forming covalent carbon contribute to good volume accommodation and high electron conductivity. The carbon-covalent amorphous Nb₂O₅ displays a high reversible capacity of 361.5 mAh g⁻¹ at 0.1 A g⁻¹ and excellent cycling stability with a capacity of 189.8 mAh g⁻¹ at a high rate of 10 A g⁻¹ after 9000 cycles. Structure characterizations reveal that the well-preserved amorphous structure without phase transition during repeated Li⁺ insertion/desertion is responsible for the superior performance. This work opens a new avenue on rational design of high-performance amorphous electrode materials for next-generation batteries.

Nature Synthesis, Published online: 29 May 2024; doi:10.1038/s44160-024-00558-w

Nature Electronics, Published online: 27 May 2024; doi:10.1038/s41928-024-01176-2

The concepts of ″Yin″ and ″Yang″ symbolizes the interplay of opposites such as heaven and earth. By employing the metaphor of ″yin″ and ″yang,″ parallels are drawn to the seemingly contradictory properties observed in hexagonal-boron nitride, where these paired properties are perceived as inherently opposite to each other. The understanding and manipulation of these contradictions would lead to a unity of opposites, which will find applications in unique circumstances.

Abstract

The exploration of 2D materials has captured significant attention due to their unique performances, notably focusing on graphene and hexagonal boron nitride (h-BN). Characterized by closely resembling atomic structures arranged in a honeycomb lattice, both graphene and h-BN share comparable traits, including exceptional thermal conductivity, impressive carrier mobility, and robust pi–pi interactions with organic molecules. Notably, h-BN has been extensively examined for its exceptional electrical insulating properties, inert passivation capabilities, and provision of an ideal ultraflat surface devoid of dangling bonds. These distinct attributes, contrasting with those of h-BN, such as its conductive versus insulating behavior, active versus inert nature, and absence of dangling surface bonds versus absorbent tendencies, render it a compelling material with broad application potential. Moreover, the unity of such contradictions endows h-BN with intriguing possibilities for unique applications in specific contexts. This review aims to underscore these key attributes and elucidate the intriguing contradictions inherent in current investigations of h-BN, fostering significant insights into the understanding of material properties.

Two-dimensional gallium sulfide (2D GaS) emitting in the ultraviolet to visible spectral range is synthesized via metal–organic chemical vapor deposition. Pulsed deposition of industry-standard precursors promotes 2D growth. The interface chemistry with the growth of a Ga adlayer as well as strain relation upon the growth of thicker layers resulting in an epitaxial relationship is revealed. Thickness control is enabled by tuning the number of GaS pulses.

Abstract

Two-dimensional (2D) materials exhibit the potential to transform semiconductor technology. Their rich compositional and stacking varieties allow tailoring materials’ properties toward device applications. Monolayer to multilayer gallium sulfide (GaS) with its ultraviolet band gap, which can be tuned by varying the layer number, holds promise for solar-blind photodiodes and light-emitting diodes as applications. However, achieving commercial viability requires wafer-scale integration, contrasting with established, limited methods such as mechanical exfoliation. Here the one-step synthesis of 2D GaS is introduced via metal–organic chemical vapor deposition on sapphire substrates. The pulsed-mode deposition of industry-standard precursors promotes 2D growth by inhibiting the vapor phase and on-surface pre-reactions. The interface chemistry with the growth of a Ga adlayer that results in an epitaxial relationship is revealed. Probing structure and composition validate thin-film quality and 2D nature with the possibility to control the thickness by the number of GaS pulses. The results highlight the adaptability of established growth facilities for producing atomically thin to multilayered 2D semiconductor materials, paving the way for practical applications.

Magnetic chains of atoms (“1D magnets”) have intriguing properties that illuminate fundamental principles in many-body physics while also promising applications in magnonics and spintronics. This article describes AgCrP₂S₆ and its family, layered crystals that host magnetic chains, focusing on their highly anisotropic properties and the additional degrees of freedom that can arise from patterning or stacking to engineer the structure.

Abstract

The exploration of 1D magnetism, frequently portrayed as spin chains, constitutes an actively pursued research field that illuminates fundamental principles in many-body problems and applications in magnonics and spintronics. The inherent reduction in dimensionality often leads to robust spin fluctuations, impacting magnetic ordering and resulting in novel magnetic phenomena. Here, structural, magnetic, and optical properties of highly anisotropic 2D van der Waals antiferromagnets that uniquely host spin chains are explored. First-principle calculations reveal that the weakest interaction is interchain, leading to essentially 1D magnetic behavior in each layer. With the additional degree of freedom arising from its anisotropic structure, the structure is engineered by alloying, varying the 1D spin chain lengths using electron beam irradiation, or twisting for localized patterning, and spin textures are calculated, predicting robust stability of the antiferromagnetic ordering. Comparing with other spin chain magnets, these materials are anticipated to bring fresh perspectives on harvesting low-dimensional magnetism.