Edge-to-Edge Oriented Self-Assembly of ReS2 Nanoflakes

Gallium-Based Liquid Metals in Rechargeable Batteries: From Properties to Applications

Gallium-based (Ga-based) liquid metals have attracted considerable interest due to their low melting points, enabling them to feature both liquid properties and metallic properties at room temperature. In light of this, Ga-based liquid metals also possess excellent deformability, high electrical and thermal conductivity, superior metal affinity, and unique self-limited surface oxide, making them popular functional materials in energy storage. This provides a possibility to construct high-performance rechargeable batteries that are deformable, free of dendrite growth, and so on. This review primarily starts with the property of Ga-based liquid metal, and then focuses on the potential applications in rechargeable batteries by exploiting these advantages, aiming to construct the correlation between properties and structures. The glorious applications contain interface protection, self-healing electrode construction, thermal management, and flexible batteries. Finally, the opportunities and obstacles for the applications of liquid metal in batteries are presented.

Soccer Ball-like Assembly of Edge-to-edge Oriented 2D-silica Nanosheets: A Promising Catalyst Support for High-Temperature Reforming

Controlled assembly of nanoparticles into well-defined assembled architectures through precise manipulation of spatial arrangement and interactions allows the development of advanced mesoscale materials with tailored structures, hierarchical functionalities, and enhanced properties. Despite remarkable advancements, the controlled assembly of highly anisotropic 2Dnanosheets is significantly challenging, primarily due to the limited availability of selective edge-to-edge connectivity compared to the abundant large faces. Innovative strategies are needed to unlock the full potential of 2D-nanomaterialsin self-assembled structures with distinct and desirable properties. This research unveils the discovery of controlled self-assembly of 2D-silica nanosheets (2D-SiNSs) into hollow micron-sized soccer ball-like shells (SA-SiMS). The assembly is driven by the physical flexibility of the 2D-SiNSs and the differential electricdouble-layer charge gradient creating electrostatic bias on the edge and face regions. The resulting SA-SiMS structures exhibit high mechanical stability, even at high-temperatures, and exhibit excellent performance as catalyst support in the dry reforming of methane. The SA-SiMS structures facilitate improved mass transport, leading to enhanced reaction rates, while the thin silica shell prevents sintering of small catalyst nanocrystals, thereby preventing coke formation. This discovery sheds light on the controllable self-assembly of 2D nanomaterials and provides insights into the design and synthesis of advanced mesoscale materials with tailored properties.

Curvature geometry in 2D materials

The two-dimensional (2D) material family can be regarded as the extreme externalization form of the matter in the planar 2D space. These atomically thin materials have abundant curvature structures, which will significantly affect their atomic configurations and physicochemical properties. Curvature engineering offers a new tuning freedom beyond the thoroughly studied layer number, grain boundaries, stacking order, etc. The precise control of the curvature geometry in 2D materials can redefine this material family. Special attention will be given to this emerging field and highlight possible future directions. With the step-by-step achievement in understanding the curvature engineering effect in 2D materials and establishing reliable delicate curvature controlling strategies, a brand-new era of 2D materials research could be developed.

A Versatile Method for the End-Functionalization of Polycarbenes

End-functionalization is an effective strategy for constructing functional materials. A method for chain-end functionalization of helical polycarbenes is herein developed that relied on Sonogashira coupling reaction. In this work, a family of helical polycarbenes with controlled molecular mass (M_n ) and low polydispersity (M_w /M_n ) is readily prepared using Pd(II) and the Wei-Phos ligand as initiator. The Pd(II) complex is confirmed to remain at the chain end of polycarbene. Subsequently, a series of terminal alkyne derivatives with interesting functional groups, including the F atom, aldehyde, or anthracene groups, are synthesized. They could be installed at the chain end of polycarbene through Sonogashira coupling reaction catalyzed by the Pd(II) complex at the chain end. Moreover, a couple of hybrid block copolymers are easily obtained by installing terminal alkynes modified by another type of polymer. The structures of the isolated polymers are confirmed by ¹ H nuclear magnetic resonance (¹ H NMR), ¹⁹ F nuclear magnetic resonance (¹⁹ F NMR), ³¹ P nuclear magnetic resonance (³¹ P NMR), and Fourier transform infrared spectroscopy (FT-IR), respectively. The self-assembly properties of the hybrid block copolymers are also investigated by atomic force spectroscopy analysis. By the hereby developed method, various functional groups can be introduced at the chain end of helical polycarbenes for constructing functional polymer materials, moreover, the transition metal residues at the end of polymer chains can be easily removed.

Atomically Thin Materials for Next-Generation Rechargeable Batteries

Atomically thin materials (ATMs) with thicknesses in the atomic scale (typically <5 nm) offer inherent advantages of large specific surface areas, proper crystal lattice distortion, abundant surface dangling bonds, and strong in-plane chemical bonds, making them ideal 2D platforms to construct high-performance electrode materials for rechargeable metal-ion batteries, metal-sulfur batteries, and metal-air batteries. This work reviews the synthesis and electronic property tuning of state-of-the-art ATMs, including graphene and graphene derivatives (GE/GO/rGO), graphitic carbon nitride (g-C₃N₄), phosphorene, covalent organic frameworks (COFs), layered transition metal dichalcogenides (TMDs), transition metal carbides, carbonitrides, and nitrides (MXenes), transition metal oxides (TMOs), and metal-organic frameworks (MOFs) for constructing next-generation high-energy-density and high-power-density rechargeable batteries to meet the needs of the rapid developments in portable electronics, electric vehicles, and smart electricity grids. We also present our viewpoints on future challenges and opportunities of constructing efficient ATMs for next-generation rechargeable batteries.

Bidirectional and reversible tuning of the interlayer spacing of two-dimensional materials

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 (MoS2) 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.

Atomic Scale Tracking of Single Layer Oxide Formation: Self-Peeling and Phase Transition in Solution

Liquid phase electron microscopy (TEM) is used to track the formation of In₂ O₃ ultrathin nanosheet in solution at atomic scale. This observation reveals that the formation of few atomic layer nanosheet goes through a complicated phase transition process from InCl₃ ^. 3H₂ O to In(OH)₃ and then to In₂ O₃ . Interestingly, the intermediate InCl₃ ^. 3H₂ O nanosheet can grow via either layer by layer or the strain-driven enation growth from precursor solution. Moreover, in situ TEM results and density functional theory (DFT) calculations demonstrate that the oleylamine is responsible for the self-peeling process. These findings can provide atomic-level insight for the understanding of how 2D nanomaterial grows and transforms in solution.

Direct fabrication of two-dimensional ReS2 on SiO2/Si substrate by a wide-temperature-range atomic layer deposition

The building of high-quality, especially thickness-controllable ReS₂, is the crux of researching it and developing its wider application. In this work, ultrathin (1-5 layers) ReS₂ with controllable thickness and improved quality is obtained on SiO₂/Si substrates, using wide-temperature-range (WTR) atomic layer deposition (ALD). First, a WTR ALD system for building thin films and in situ annealing is constructed. ReS₂ of precise thicknesses can be achieved by regulating the number of ALD cycles, controlling the reaction temperature and plasma treatment. In particular, a method of in situ H₂S annealing is used to reduce S defects, which improves the quality of ReS₂. After annealing, the atomic ratio of S/Re in ReS₂ increases from 1.74 to 1.92, considering the presence of Re-O bond at the SiO₂-ReS₂ interface, which indicates that the S defects in ReS₂ films are completely eliminated at annealing temperature of 850 °C and 900 °C. In particular, at an annealing temperature of 900 °C, ReS₂ recrystallizes to form about 120 nm triangular grains, and its frictional force is reduced by 27.5% compared with the as-grown ReS₂.

Voltage Stimulated Anion Binding of Metalloporphyrin-induced Crystalline 2D Nanoflakes

Voltage-stimulated redox-active materials have received significant attention in the field of organic electronics and sensor technology. Such stimuli-responsive materials trigger the formation of crystalline nanostructures and facilitate the design of efficient smart devices hitherto unknown. Herein, we report that free-base and metallo-tetratolylporphyrin-linked ferrocene derivatives (H₂ TTP-Fc and ZnTTP-Fc) undergo distinct proton/anion binding mechanism in CHCl₃ during bulk electrolysis at applied voltage of 1.4 V to give [H₄ TTP-Fc]⁺ Cl^- and H⁺ [(Cl)ZnTTP-Fc]^- followed by nanospheres and crystalline 2D nanoflakes formation, confirmed by SEM and TEM images, by methanol vapor diffusion (MVD) approach. Moreover, X-ray diffraction analysis suggest that protonated H₂ TTP-Fc aggregates exhibit amorphous nature, whereas H⁺ [(Cl)ZnTTP-Fc]^- depict crystalline nature from layer-by-layer arrangement of nanoflakes assisted by π-π stacking and ion-dipole interactions.

Applications of 2D MXenes in energy conversion and storage systems

This article provides a comprehensive review of MXene materials and their energy-related applications.

Engineering 2D Architectures toward High-Performance Micro-Supercapacitors

The rise of micro-supercapacitors is satisfying the demand for power storage in portable devices and wireless gadgets. But the miniaturization of the energy-storage components is significantly limited by their energy density. Electrode materials with adequate electrochemical active surfaces are therefore required for improving performance. 2D materials with ultralarge specific surface areas offer a broad portfolio of the development of high-performance micro-supercapacitors in spite of their several critical drawbacks. An architecture engineering strategy is therefore developed to break these natural limits and maximize the significant advantages of these materials. Based on the approaches of phase transformation, intercalation, surface modification, material hybridization, and hierarchical structuration, 2D architectures with improved conductivity, enlarged specific surface, enhanced redox activity, as well as the unique synergetic effect exhibit great promise in the application of miniaturized supercapacitors with highly enhanced performance. Herein, the architecture engineering of emerging 2D materials beyond graphene toward optimizing the performance of micro-supercapacitors is discussed, in order to promote the application of 2D architectures in miniaturized energy-storage devices.

Self-Adapting Wettability of ReS2 under a Constant Stimulus

Responsive materials (RMs) are attracting intense interest for their critical roles in intelligent designs. So far, only by means of applying complicated and multiple stimuli can physical properties of the solid surface realize a transition, limiting their practical applications. Here, the smart self-adapting wettability (SAW) of ReS₂ under sustaining light irradiation, which breaks the stereotype that a single stimulus leads to a monotonic change in properties or structures, is presented. The additional valence electron and defects ensure ReS₂ has a stronger gas adsorption and better hydrolysis capability. Combining theoretical calculations and experimental results, its mechanism, including three stages, namely, hydroxyl substitution, formation of hydrogen bonds, and water desorption, is confirmed. Notably, other transition metal dichalcogenides covering MoS₂ and WS₂ exhibit a similar automatic transition of hydrophobic-hydrophilic-hydrophobic state. This unique SAW provides a brand-new insight to broaden the applications of RMs, which will undoubtedly pave a novel way in RMs design and further devices optimization.

Morphological Control of Coil-Rod-Coil Molecules Containing m-Terphenyl Group: Construction of Helical Fibers and Helical Nanorings in Aqueous Solution

Rod-coil molecules, composed of rigid segments and flexible coil chains, have a strong intrinsic ability to self-assemble into diverse supramolecular nanostructures. Herein, we report the synthesis and the morphological control of a new series of amphiphilic coil-rod-coil molecular isomers 1-2 containing flexible oligoether chains. These molecules are comprised of m-terphenyl and biphenyl groups, along with triple bonds, and possess lateral methyl or butyl groups at the coil or rod segments. The results of this study suggest that the morphology of supramolecular aggregates is significantly influenced by the lateral alkyl groups and by the sequence of the rigid fragments in the bulk and in aqueous solution. The molecules with different coils self-assemble into lamellar or oblique columnar structures in the bulk state. In aqueous solution, molecule 1a, with a lack of lateral groups, self-assembled into large strips of sheets, whereas exquisite nanostructures of helical fibers were obtained from molecule 1b, which incorporated lateral methyl groups between the rod and coil segments. Interestingly, molecule 1c with lateral butyl and methyl groups exhibited a strong self-organizing capacity to form helical nanorings. Nanoribbons, helical fibers, and small nanorings were simultaneously formed from the 2a-2c, which are structural isomers of 1a, 1b, and 1c. Accurate control of these supramolecular nanostructures can be achieved by tuning the synergistic interactions of the noncovalent driving force with hydrophilic-hydrophobic interactions in aqueous solution.

Highly Efficient Photocatalytic Hydrogen Evolution by ReS2 via a Two-Electron Catalytic Reaction

Highly efficient photocatalytic hydrogen evolution (PHE) is highly desirable for addressing the global energy crisis and environmental problems. Although much attention has been given to electron-hole separation, ridding photocatalysts of poor efficiency remains challenging. Here, a two-electron catalytic reaction is developed by utilizing the distinct trion behavior of ReS₂ and the efficient reduction of two H⁺ (2H⁺ + 2e^- → H₂ ) is realized. Due to the monolayer-like structure of the catalyst, the free electrons in ReS₂ can be captured by the tightly bound excitons to form trions consisting of two electrons and one hole. These trions can migrate to the surface and participate in the two-electron reaction at the abundant active sites. As expected, such a two-electron catalytic reaction endows ReS₂ with a PHE rate of 13 mmol g^-1 h^-1 under visible light irradiation. Meanwhile, this reaction allows the typically poor PHE efficiency of pure transition metal dichalcogenides to be overcome. The proposed two-electron catalytic reaction provides a new approach to the design of photocatalysts for PHE.

Few-Layer Antimonene: Anisotropic Expansion and Reversible Crystalline-Phase Evolution Enable Large-Capacity and Long-Life Na-Ion Batteries

Two-dimensional (2D) antimonene is a promising anode material in sodium-ion batteries (SIBs) because of its high theoretical capacity of 660 mAh g^-1 and enlarged surface active sites. However, its Na storage properties and sodiation/desodiation mechanism have not been fully explored. Herein, we propose the sodiation/desodiation reaction mechanism of 2D few-layer antimonene (FLA) based on results acquired by in situ synchrotron X-ray diffraction, ex situ selected-area electron diffraction, and theoretical simulations. Our study shows that the FLA undergoes anisotropic volume expansion along the a/b plane and exhibits reversible crystalline phase evolution (Sb ⇋ NaSb ⇋ Na₃Sb) during cycling. Density-functional theory calculations demonstrate that the FLA has a small Na-ion diffusion barrier of 0.14 eV. The FLA delivers a larger capacity of 642 mAh g^-1 at 0.1 C (1 C = 660 mA g^-1) and a high rate capability of 429 mAh g^-1 at 5 C and maintains a stable capacity of 620 mA g^-1 at 0.5 C with 99.7% capacity retention from the 10th to the 150th cycle. Considering the 660 mAh g^-1 theoretical capacity of Sb, the electrochemical utilization of Sb atoms of FLA is as high as 93.9% at a rate of 0.5 C for over 150 cycles, which is the highest capacity and Sb utilization ratio reported so far. Our study discloses the Na storage mechanism of 2D FLA, boosting promising applications of 2D materials for advanced SIBs.

Largely enhanced photocatalytic activity of Au/XS2/Au (X = Re, Mo) antenna-reactor hybrids: charge and energy transfer

An antenna-reactor hybrid coupling plasmonic antenna with catalytic nanoparticles is a new strategy to optimize photocatalytic activity. Herein, we have rationally proposed a Au/XS₂/Au (X = Re, Mo) antenna reactor, which has a large Au core as the antenna and small satellite Au nanoparticles as the reactor separated by an ultrathin two-dimensional transition-metal dichalcogenide XS₂ shell (∼2.6 nm). Due to efficient charge transfer across the XS₂ shell as well as energy transfer via coupling of the Au antenna and Au reactor, the photocatalytic activity has been largely enhanced: Au/ReS₂/Au exhibits a 3.59-fold enhancement, whereas Au/MoS₂/Au exhibits a 2.66-fold enhancement as compared to that of the sum of the three individual components. The different enhancement in the Au/ReS₂/Au and Au/MoS₂/Au antenna-reactor hybrid is related to the competition and cooperation of charge and energy transfer. These results indicate the great potential of the Au/XS₂/Au antenna-reactor hybrid for the development of highly efficient plasmonic photocatalysts.

Thermally Induced Bending of ReS2 Nanowalls

Among the variety of stimuli-responsive materials, temperature-responsive materials (TRMs) can adapt to the surrounding environment in the presence of a thermal stimulus, and they have attracted considerable attention in sensors, actuators, and surface engineering. However, polymers, as the most representative TRMs, are far from ideal with respect to long-term reliability and durability. Here, for the first time, an inorganic material, ReS₂ , is analyzed, which possesses an unexpected temperature-responsive behavior that is triggered by stable and reversible thermally induced bending (TIB). Due to thermal fluctuations in the ReS₂ layers, intrinsic ripples tend to aggravate rapidly with rising temperature. Then, the weak interlayer interaction of ReS₂ is further weakened, thus resulting in interlayer sliding. Due to a decrease in bending rigidity with increasing temperature, out-of-plane bending spontaneously occurs in the ReS₂ layers. Interestingly, this TIB of ReS₂ can recover to its initial configuration when the temperature drops, which is further confirmed by the reversible wetting measurement. Above all, the TIB behavior of ReS₂ exhibits great potential in smart applications, such as smart windows and microfluidic devices, and fills the significant gaps of inorganic TRMs.