High‐entropy alloys (HEAs) are based on five or more principal elements with equal or nearly equal molar fractions and possess many significant advantages over traditional alloys, including high ...strength and hardness, excellent corrosion resistance, outstanding thermal stability, and irradiation resistance. Phase structure plays a vital role in determining the property of HEAs. For further enhancing the performance of HEAs in various application fields, a controllable synthesis with desired phases is required. In this review, the diverse phase structures of HEAs and the related properties are first introduced. Then, alternative tuning strategies to promote the desired phase structure of HEAs are focused upon. Property adjusting of phase‐engineered HEAs is also discussed in depth. Lastly, some insights into the challenges and future prospects in this rapidly emerging research field are provided.
Phase engineering of high‐entropy alloys (HEAs) is comprehensively reviewed. HEAs with rich constituent elements exhibit many remarkable properties that are greatly influenced by phase structure. For further exploring the properties of HEAs, controllable synthesis with desired phases is required. The diverse phase structures, phase‐tuning strategies, and property adjusting of phase‐engineered HEAs is presented and discussed in depth.
Two-dimensional (2D) materials have attracted tremendous research interest since the breakthrough of graphene. Their unique optical, electronic, and mechanical properties hold great potential for ...harnessing them as key components in novel applications for electronics and optoelectronics. Their atomic thickness and exposed huge surface even make them highly designable and manipulable, leading to the extensive application potentials. What’s more, after acquiring the qualification for being the candidate for next-generation devices, the assembly of 2D materials monomers into mass or ordered structure is also of great importance, which will determine their ultimate industrialization. By designing the monomers and regulating their assembling behavior, the exploration of 2D materials toward the next-generation circuits can be spectacularly achieved. In this review, we will first overview the emerging 2D materials and then offer a clear guideline of varied physical and chemical strategies for tuning their properties. Furthermore, assembly strategies of 2D materials will also be included. Finally, challenges and outlooks in this promising field are featured on the basis of its current progress.
Conspectus Due to the confinement of the charge, spin, and heat transport in the plane, graphene and related two-dimensional (2D) materials have been demonstrated to own many unique and excellent ...properties and witnessed many breakthroughs in physics. They show great application potential in many fields, especially for electronics and optoelectronics. However, a bottleneck to widespread applications is precise and reliable fabrication, in which the control of the layer number and domain assembly is the most basic and important since they directly determine the qualities and properties of 2D materials. The chemical vapor deposition (CVD) strategy was regarded as the frontrunner to achieve this target, and the design of the catalytic substrate is of great significance since it has the most direct influence on the catalysis and mass transfer, which can be the most essential elemental steps. In recent years, as compared to traditional solid metal catalysts, the emergence of liquid metal catalysts has brought a brand-new perspective and contributes to a huge change and optimization in the fabrication of 2D materials. On one hand, strictly self-limited growth behavior is discovered and is robust to the variation of the growth parameters. The atoms in the liquid metal tend to move intensely and arrange in an amorphous and isotropic way. The liquid surface is smooth and isotropic, and the vacancies in the fluidic liquid phase enable the embedding of heteroatoms. The phase transition from liquid to solid will facilitate the unique control of the mass-transfer path, which can trigger new growth mechanisms. On the other hand, the excellent rheological properties of liquid metals allow us to explore self-assembly of the 2D materials grown on the surface, which can activate new applications based on the derived collective properties, such as the integrated devices. Indeed, liquid metals show many unique behaviors in the catalytic growth and assembly of 2D materials. Thus, this Account aims to highlight the controllable fabrication of graphene and related 2D materials on liquid metals. By utilizing the phase transition of liquid metals, the segregation of precursors in the bulk can be controlled, leading to self-limited growth. By utilizing the fluidity of the liquid metals, 2D material crystals can achieve self-assembly on their surface, including oriented stitching, ordered assembly, and heterostacking, which enables the creation of new multilevel or hybrid structures, leading to property and function extension and even the emergence of new physics. Finally, the unique liquid characteristic of liquid metals can also offer us new ideas about the transfer process. By utilizing the shear transformation of liquid metals, the direct sliding transfer of 2D materials onto arbitrary substrates can be realized. The research concerning the self-limited growth, self-assembly, and sliding transfer of 2D materials on liquid metals is just raising the curtain on the behavioral study of 2D materials on liquid metals. We believe these primary technology developments revealed by liquid metals will establish a solid foundation for both fundamental research and practical application of 2D materials.
Metal halide perovskites, as a new generation of optoelectronic materials, have attracted a great deal of interest due to their remarkable intrinsic properties. Due to the excellent optoelectronic ...properties, the perovskite crystals are widely used in lasers, photodetectors, X-ray detectors and solar cells. Considering the device performance and fabrication requirements, proper thickness of the crystal is required to avoid carrier loss and simultaneously ensure sufficient light absorption, which can realize the full potential of its excellent carrier transport property. Thus, the fabrication of perovskite crystal in a thin film with an adjustable thickness is highly desirable. The space-confined method has been demonstrated to be an effective way of preparing perovskite with controlled thickness. In this method, the thickness of perovskite can be regulated flexibly in a geometric confined space. Moreover, the size, quality and architecture of perovskite crystal films are also major concerns for practical photoelectric devices, which can also be optimized by the space-confined method owing to its good adaptability towards various modified strategies. In a word, the space-confined method is not only a simple and conventional way to adjust the thickness of perovskite crystal films, but also provides a platform to optimize their size, quality and architecture through applying appropriate strategies to the confined space. Herein, we review the space-confined growth of perovskite crystal films. Particularly, various modified strategies based on the space-confined method applied to the optimization of thickness, size, quality and architecture are highlighted. Then the stability investigating and component regulating of perovskite crystal films would be also mentioned. Furthermore, the correlation between the perovskite thickness and the device performance is discussed. Finally, several key challenges and proposed solutions of perovskite thin films based on the space-confined method are discussed.
Two-dimensional (2D) gallium nitride (GaN) has been highly anticipated because its quantum confinement effect enables desirable deep-ultraviolet emission, excitonic effect and electronic transport ...properties. However, the currently obtained 2D GaN can only exist as intercalated layers of atomically thin quantum wells or nanometer-scale islands, limiting further exploration of its intrinsic characteristics. Here, we report, for the first time, the growth of micrometer-sized 2D GaN single crystals on liquid metals via a surface-confined nitridation reaction and demonstrate that the 2D GaN shows uniformly incremental lattice, unique phonon modes, blue-shifted photoluminescence emission and improved internal quantum efficiency, providing direct evidence to the previous theoretical predictions. The as-grown 2D GaN exhibits an electronic mobility of 160 cm2·V–1·s–1. These findings pave the way to potential optoelectronic applications of 2D GaN single crystals.
Interlayer spacing is expected to influence the properties of multilayer two-dimensional (2D) materials. However, the ability to non-destructively regulate the interlayer spacing bidirectionally and ...reversibly is challenging. Here we report the preparation of 2D materials with tunable interlayer spacing by introducing active sites (Ce ions) in 2D materials to capture and immobilize Pt single atoms. The strong chemical interaction between active sites and Pt atoms contributes to the intercalation behavior of Pt atoms in the interlayer of 2D materials and further promotes the formation of chemical bonding between Pt atom and host materials. Taking cerium-embedded molybdenum disulfide (MoS
) as an example, intercalation of Pt atoms enables interlayer distance tuning via an electrochemical protocol, leading to interlayer spacing reversible and linear compression and expansion from 6.546 ± 0.039 Å to 5.792 ± 0.038 Å (~11 %). The electronic property evolution with the interlayer spacing variation is demonstrated by the photoluminescence (PL) spectra, delivering that the well-defined barrier between the multilayer and monolayer layered materials can be artificially designed.
Ultra-thin III-V semiconductors, which exhibit intriguing characteristics, such as two-dimensional (2D) electron gas, enhanced electron-hole interaction strength, and strongly polarized light ...emission, have always been anticipated in future electronics. However, their inherent strong covalent bonding in three dimensions hinders the layer-by-layer exfoliation, and even worse, impedes the 2D anisotropic growth. The synthesis of desirable ultra-thin III-V semiconductors is hence still in its infancy. Here we report the growth of a majority of ultra-thin III-V single crystals, ranging from ultra-narrow to wide bandgap semiconductors, through enhancing the interfacial interaction between the III-V crystals and the growth substrates to proceed the 2D layer-by-layer growth mode. The resultant ultra-thin single crystals exhibit fascinating properties of phonon frequency variation, bandgap shift, and giant second harmonic generation. Our strategy can provide an inspiration for synthesizing unexpected ultra-thin non-layered systems and also drive exploration of III-V semiconductor-based electronics.
Recent studies have revealed robust metabolic changes during cell differentiation. Mitochondria, the organelles where many vital metabolic reactions occur, may play an important role. Here, we report ...the involvement of SIRT3-regulated mitochondrial stress in osteoblast differentiation and bone formation. In both the osteoblast cell line MC3T3-E1 and primary calvarial osteoblasts, robust mitochondrial biogenesis and supercomplex formation were observed during differentiation, accompanied by increased ATP production and decreased mitochondrial stress. Inhibition of mitochondrial activity or an increase in mitochondrial superoxide production significantly suppressed osteoblast differentiation. During differentiation, SOD2 was specifically induced to eliminate excess mitochondrial superoxide and protein oxidation, whereas SIRT3 expression was increased to enhance SOD2 activity through deacetylation of K68. Both SOD2 and SIRT3 knockdown resulted in suppression of differentiation. Meanwhile, mice deficient in SIRT3 exhibited obvious osteopenia accompanied by osteoblast dysfunction, whereas overexpression of SOD2 or SIRT3 improved the differentiation capability of primary osteoblasts derived from SIRT3-deficient mice. These results suggest that SIRT3/SOD2 is required for regulating mitochondrial stress and plays a vital role in osteoblast differentiation and bone formation.
Oxygen evolution reaction(OER) plays an important role in many electrochemical systems. However, its sluggish kinetics severely limits the development of next-generation energy technologies. ...Recently, two-dimensional(2D) metal-organic frameworks(MOFs) have attracted much attention as a class of promising electrocatalysts. Their diverse components and tunable structures provide a new platform to design and explore ideal electrocatalysts. The ultrathin characteristics including high specific surface area, abundant exposed metal sites and fast electronic transfer further promote the electrocatalytic performance of 2D MOFs. Therefore, many attempts have been made in synthesizing 2D MOF-based electrocatalysts in recent years. This review focuses on the strategies to fabricate 2D MOFs with high electrocatalytic performances for OER. The discussion on challenge and development of their electrocatalytic application is also presented.
PDF
