Thermally Induced Bending of ReS2 Nanowalls

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.

ReS2 Cocatalyst Improves the Hydrogen Production Performance of the CdS/ZnS Photocatalyst

Photocatalysis provides an exciting solution to the current growing energy challenge. However, the activity and stability of photocatalysts are two important issues in photocatalytic applications. In this work, we have successfully developed an efficient and stable photocatalyst by loading ReS₂ nanoparticles onto a CdS/ZnS heterojunction. After loading ReS₂, there is a strong interaction between the CdS/ZnS heterojunction and ReS₂, which accelerates the photogenerated charge migration and effectively inhibits the recombination of photogenerated electrons and holes. Accordingly, CdS/ZnS-ReS₂ displays excellent photocatalytic activity and stability with the highest hydrogen production rate of 10 722 μmol g^-1 h^-1, which is approximately 178 times higher than that of the pure CdS and 5 times better than that of CdS/ZnS. This work not only facilitates solar energy conversion to improve photocatalytic activity and stability but also broadens the application of ReS₂ as a cocatalyst.

Abnormal temperature-dependent photoluminescence characteristics of ReS2nanowalls

Two samples with [001] orientated rhenium disulfide (ReS₂) nanowalls (NWs) grown above and in front of precursor (NH₄ReO₄) by chemical vapor deposition were investigated. The temperature-dependent photoluminescence (PL) indicated that the PL peak exhibited linear blue-shift at a rate of ∼0.24 meV K^-1with increasing the temperature from 10 to 300 K, while the linewidth monotonically increased due to the exciton-phonon interaction. This abnormal blue-shift of PL emission energy, which is explained by a competition between the band gap shrinkage and the energy level degeneracy with respect to the increase of temperature and lattice constant, enables ReS₂NWs to possess great potential for development of thermal sensors. In addition, exciton localization effect in the ReS₂NWs from abundant edges and weak interlayer interaction was also observed to be related to the height and density of ReS₂NWs. These results not only enrich the understanding for exciton dynamics in ReS₂NWs, but also help to exploit ReS₂NWs for device applications.

Noble metal modified ReS2 nanocavity for surface-enhanced Raman spectroscopy (SERS) analysis

The rhenium disulphide (ReS₂) nanocavity-based surface enhanced Raman scattering (SERS) substrates ware fabricated on the gold-modified silicon pyramid (PSi) by thermal evaporation technology and hydrothermal method. In this work, the ReS₂ nanocavity was firstly combined with metal nanostructures in order to improve the SERS properties of ReS₂ materials, and the SERS response of the composite structure exhibits excellent performance in sensitivity, uniformity and repeatability. Numerical simulation reveals the synergistic effect of the ReS₂ nanocavity and the plasmon resonance generated by the metal nanostructures. And the charge transfer between the metal, ReS₂ and the analytes was also verified and plays an non-ignorable role. Besides, the plasmon-driven reaction for p-nitrothiophenol (PNTP) to p,p'-dimercaptobenzene (DMAB) conversion was successfully in-situ monitored. Most importantly, it is found for the first time that the SERS properties of ReS₂ nanocavity-based substrates are strongly temperature dependent, and the SERS effect achieves the best performance at 45 °C. In addition, the low concentration detection of malachite green (MG) and crystal violet (CV) molecules in lake water shows its development potential in practical application.

Single-Metallic Thermoresponsive Coordination Network as a Dual-Parametric Luminescent Thermometer

The single-metallic coordination networks (CNs), simultaneously exhibiting temperature-dependent lifetime (TDLT) and emission band shift (TDEBS), are desirable for application in luminescent thermometers with high accuracy and reliability in a large temperature range. Nonetheless, up to date, there are no reports on such kinds of materials due to the lack of in-depth understanding of the origin of TDLT and TDEBS at a molecule level, being critical for exploiting a universal approach to design a dual-parametric CN phosphorescent thermometer (CN-PT). Herein, we have constructed a thermoresponsive CN [Cu₂(L1)Br₂]_∞ (IAM21-1, L1 = N¹,N⁶-di(pyridin-3-yl)adipamide) via a flexible-ligand-implanted strategy. The TDLT and TDEBS properties of IAM21-1 enable it to be applied as a single-metallic dual-parametric CN-PT in 50-500 K, which is the widest temperature range reported so far. The combination of structure analysis and DFT calculations demonstrates that the redshift of the emission band upon the decreasing temperature originates from the reversible skeleton-shrinkage-triggered narrower band gap. This work has unveiled the origin of TDLT and TDEBS properties and proposed an efficient strategy for designing dual-parametric CN-PTs.

Unique cation-template three-dimensional hybrid material demonstrates dielectric switchable response

The strict tolerance space of three-dimensional (3D) crystalline structures is still a significant challenge in the area of switching dielectrics in comparison with lower-dimensional structures. Generally, the function of crystalline materials can be given or adjusted by controlling the environment in which synthesis takes place or the packing rearrangement. Using this method, special functional enhancements or changes in the dielectrics can be realized by improving the synthetic strategies. Here, a 3D switchable dielectric compound [MeHdabco]K(BF4)3 was achieved by employing the temperature selective effect. In particular, its structure is completely different from the usual 3D perovskite structure, which is constructed using two different cation-template frameworks. Moreover, the 3D [MeHdabco]K(BF4)3 shows a structural phase transition at 358 K. The thermal analysis (differential scanning calorimetry (DSC)) and X-ray diffractometry results provided evidence of these phase changes. This work provides a feasible strategy that can be used to achieve the different structures of an 'isomer', and enrich the method used for designing diverse functional materials.

Flexible temperature sensors based on carbon nanomaterials

Flexible temperature sensors based on carbon nanomaterials can be attached to the surface of human skin or curved surfaces directly for continuous and stable data measurements, and have attracted extensive attention in myriad areas.

2D Re-Based Transition Metal Chalcogenides: Progress, Challenges, and Opportunities

The rise of 2D transition-metal dichalcogenides (TMDs) materials has enormous implications for the scientific community and beyond. Among TMDs, ReX2 (X = S, Se) has attracted significant interest regarding its unusual 1T' structure and extraordinary properties in various fields during the past 7 years. For instance, ReX2 possesses large bandgaps (ReSe2: 1.3 eV, ReS2: 1.6 eV), distinctive interlayer decoupling, and strong anisotropic properties, which endow more degree of freedom for constructing novel optoelectronic, logic circuit, and sensor devices. Moreover, facile ion intercalation, abundant active sites, together with stable 1T' structure enable them great perspective to fabricate high-performance catalysts and advanced energy storage devices. In this review, the structural features, fundamental physicochemical properties, as well as all existing applications of Re-based TMDs materials are comprehensively introduced. Especially, the emerging synthesis strategies are critically analyzed and pay particular attention is paid to its growth mechanism with probing the assembly process of domain architectures. Finally, current challenges and future opportunities regarding the controlled preparation methods, property, and application exploration of Re-based TMDs are discussed.

The mechanism of the modulation of electronic anisotropy in two-dimensional ReS2

Although the anisotropy and strategies for the modulation of the anisotropy in ReS2 have been widely reported, a comprehensive study on the inherent electronic anisotropy of ReS2 is still absent to date; therefore, the mechanism of anisotropy evolution is ambiguous as well. In this study, we have conducted a systematic investigation on the evolution of electronic anisotropy in bilayer ReS2, under the modulation of charge doping levels and temperature. It is found that the adjustability of electronic anisotropy is largely attributed to the angle-dependent scattering from defects or vacancies at a low doping level. At a high doping level, in contrast, the inherent electronic anisotropy can be recovered by filling the traps to attenuate the influence of scattering. This work renders insights into the exploration of electronic anisotropy in 2D materials.

Three-Dimensional Metal-Free Molecular Perovskite with a Thermally Induced Switchable Dielectric Response

Temperature-responsive materials with switching physical properties have been widely researched. Among them, the switchable dielectric perovskite materials show potential applications in the electrical and electronic industries and even the intelligence industries. However, perovskite oxides and hybrid organic-inorganic perovskites, as the most representative switchable dielectric materials, are limited by bad biocompatibility. Herein, we report temperature-dielectric-responsive metal-free perovskite (H₂dabco)(NH₄)[BF₄]₃ constructed by the strategy of substituting the B site in the general formula ABX₃ (doubly protonated 1,4-diazabicyclo[2.2.2]octane = H₂dabco). Meanwhile, structurally similar hybrid material (H₂dabco)Rb[BF₄]₃ was designed as a control. They exhibit similar phase-transition characteristics and dielectric response behaviors around 333 K. More interestingly, the ordered-disordered transformation of their organic "spherical" cations (H₂dabco) was deemed to produce their phase transitions and dielectric response switching. Given its ability to generate a dielectric response, (H₂dabco)(NH₄)[BF₄]₃ will show the potential application of metal-free perovskite in a future thermal sensing device.

Enhanced charge transport in ReSe2-based 2D/3D electrodes for efficient hydrogen evolution reaction

Ultra-high-density ReSe₂ nanoflakes with uniform small 2D size were grown on porous carbon cloth by CVD. The 2D/3D construction gave more active catalytic sites, and the small size effect and the interfacial C–Se bonding facilitated electron transport between ReSe₂ and PCC.

Micro-structured medium with large isotropic negative thermal expansion

A challenge in nano- and micro-mechanics is the realization of innovative materials exploiting auxetic behaviour to tailor thermal expansion properties. For this purpose, a new class of micro-structured media possessing an extremely wide range of tunable (positive, negative or even zero) thermal expansion is proposed and analytically and experimentally assessed. For this class of isotropic Mechanical-Auxetic Thermal-Shrinking media, the effective coefficient of thermal expansion is explicitly linked to two microstructural variables via a simple relation, allowing the design with desired values. The theoretical predictions for the negative thermal properties are fully validated by the experimental and numerical outcomes. The simplicity of the proposed structure makes the design useful for the production of a new generation of advanced media, with applications ranging from micromechanical devices to large civil and space structures.

Advanced Artificial Muscle for Flexible Material-Based Reconfigurable Soft Robots

Flexible material-based soft robots are widely used in various areas. In many situations, the suitable soft robots should be rapidly fabricated to complete the urgent tasks (such as rescue), so the facile fabricating methods of the multifunctional soft robots are still in urgent needs. In this work, the origami structure is employed to design vacuum-powered silicone rubber artificial muscles, which can perform multiple motions, including contraction, bending, twisting, and radial motions. Artificial muscles can be used for rapid reconfiguration of different soft robots, just like the "building bricks". Based on these artificial muscles, four soft robots with different functions, including an omnidirectional quadruped robot, a flexible gripper, a flexible wrist, and a pipe-climbing robot, are reconfigured to complete different tasks. The proposed origami artificial muscles offer a facile and rapid fabricating method of flexible material-based soft robots, and also greatly improve the utilization rate of flexible materials.

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.

Chemical vapor deposition growth of ReS2 nanowires for high-performance nanostructured photodetector

Rhenium disulfide (ReS2) is a recently discovered next-generation transition metal dichalcogenides (TMDs) material that exhibits unique properties, which have resulted in its wide use in the fabrication of electronic and optoelectronic devices. Studies on ReS2 have mainly focused on the synthesis and applications of two-dimensional (2D) materials, while studies on one-dimensional (1D) ReS2 have yet to be reported. Herein, 1D single-crystal ReS2 nanowires have been synthesized successfully for the first time via chemical vapor deposition (CVD) and utilized as the active layer in a nanostructured photodetector. The crystal structure, phonon vibration modes, and chemical states of the single-crystal ReS2 nanowires have been investigated. Furthermore, the nanostructured photodetector using single-crystal ReS2 nanowires as the active layer and Ag nanowire networks as the transparent electrodes exhibited excellent performance, including a higher photoresponsivity (5.08 × 105), the highest external quantum efficiency (1.07 × 106), and the largest specific detectivity (6.1 × 1015) among ReS2 nanostructure-based photodetectors reported to date. Furthermore, the photodetector performance under vacuum conditions was investigated, which provides some information on the work mechanism of the ReS2 photodetector.