Flexible sensors demonstrate exceptional adaptability across human-computer interaction, health monitoring, and robotic systems. However, sensing materials suffer from inadequate conformation capability and microstructural inaccuracies, resulting in function deficiencies. This review examines composite hydrogel formulations that incorporate conductive nanofillers, with particular emphasis on 2D nanomaterials, whose functional tunability enables precise regulation of electrical and interfacial properties. The strategic integration of microstructures further improves sensor sensitivity, durability, and environmental adaptability. We also examine implementation of flexible sensors based on 3D-printed hydrogel in emerging applications including pH monitoring, glucose detection, and food safety assessment. We suggest that future development prioritize elucidating sensing mechanisms, achieving multifunctional integration, advancing material engineering, and refining precision manufacturing. Particularly promising research directions include developing intelligent tactile feedback systems for humanoid robots and creating capsule robot-integrated platforms for gastrointestinal disease monitoring.

Scalable growth of single-crystal transition metal dichalcogenides (TMDs) across wafer-scale substrates remains a critical challenge hindering their practical adoption in next-generation electronics. We developed a direct growth in confined pixel cells for synthesizing aligned wafer-scale, single-crystal 2H-MoTe2 arrays en route to mass production. By regulating pixel cell dimensions to control the nucleation process, we demonstrate the successful achievement of single nucleation in the individual pixel cell, leading to a single-crystal 2H-MoTe2 patterned array. We validate that this synthesis strategy can be extended to other pattern geometries, as well as on other substrates, including amorphous SiO2, crystalline silicon, and sapphire. Fabricated field-effect transistor (FET) and photodetector arrays display a carrier mobility of 43 +/- 5 cm2 V-1 s-1 and a responsivity of 31 +/- 6 mA W-1, evidencing exceptional electrical and optoelectronic uniformity. Our approach establishes a pathway for semiconductor chemistry that leads to the industrial application of TMD materials.

The van der Waals (vdWs) integration of two-dimensional (2D) materials offers a versatile fabrication possibility for next-generation image sensors. However, there is a conflict between the desired small channel length and lateral device structures, superseding the depletion region, with a large footprint. Here, we propose a vdWs-integrated crossbar array structure utilizing a vertical 1T ' /2H-MoTe2 /ITO structure for visible and near-infrared imaging. Such a crossbar design employs 2H-MoTe2 layers as a vertical and adjustable atomic-scale channel with a large illumination area, which in turn effectively enhances the photoresponse. Additionally, the asymmetric electrode contacts consist of an ohmic contact in the 1T ' /2H-MoTe2 homojunction and a Schottky contact on the other side, contributing to self-powered photodetection. With these designs, the self-powered responsivity and detectivity reach 4.6 A W-1 and 5.8 & times; 10 13 cm Hz1/2W-1 with 23-nm channel thickness. This vdWs-integrated image sensor provides an alternative strategy for solving optimal performance and integration problems of 2D materials for the advancement of optoelectronics.

Visible-range single-photon emitters (SPEs), based on hexagonal boron nitride (hBN), with exceptional optical performance have become an outstanding candidate for quantum optical technology. However, the control of the carbon defect structures to obtain uniform and confined band structure remains elusive, restricting their integration into on-chip quantum devices. Here, we demonstrate tuning of the defect structure of hBN to precisely control the emission in SPEs. The defect structure engineering from CB (carbon substituted at the boron site) to C2B-CN (carbon doped into two boron sites and one nitrogen site) carbon defect conversion in hBN is realized by regulating the carbon concentration from 0.0005 at % to 0.082 at % in Cu substrates to adjust the carbon diffusion during the CVD process. Meanwhile, the zero-phonon line exhibits a precise shift from the range of 600-610 nm to 630-640 nm; these shifts of the spectral features are further supported by density functional theory results, reflected in changes in the band structure, vibrational degrees of freedom, and electronic transitions. The SPE emission spectrum serves as a valuable tool for identifying the footprint of a carbon point defect structure change. Our project offers evidence of achieving structured defect engineering for tailored emission properties and showcases potential for the integration of advanced 2D material engineering into on-chip quantum devices.

The direct synthesis of wafer-scale single-crystal transition metal dichalcogenides (TMDs) remains challenging, albeit with enormous potential applications as semiconductors. In this work, we demonstrate the feasibility of using single-crystal 2H-MoTe2 films as templates, followed by a sequential selenium substitution reaction to synthesize a variety of TMDs and their heterostructures. We also demonstrate the synthesis of a MoTe2/MoSe2 lateral heterostructure with various substitution temperatures for Se substitution in 1T' and 2H phase MoTe2. Computational results illustrate that Se substitution is likely to start at Te vacancy sites, where generated strain lowers the energy barrier for further substitution, leading to a chain reaction that propagates until the entire layer is selenized. The obtained MoSe2 shows a high hole mobility of 32 cm2 V-1 s-1, comparable to the 2.8-31.6 range from mechanically exfoliated samples. Consequently, this MoSe2-based photodetector shows a comparable responsivity of 41 mA W-1 under near-infrared (1060 nm) illumination.

A series of micro-mesoporous MnCeOx solid solution catalysts with various Mn/Ce molar ratios were successfully prepared using a facile chelating sol-gel method, and were studied for the total oxidation of propane. Mn1Ce1Ox exhibited the highest catalytic activity with a T90 = 255.5 ℃, which was 40 ℃ lower than that of pure Mn2O3. The superior performance was owing to the synergistic effect between Mn and Ce in Mn-Ce solid solution structure, which possesses a higher Mn4+/Mn ion ratio, stronger reducibility, and more active oxygen species. Meanwhile, the mechanism on total oxidation of propane over MnOx and MnCeOx was investigated by in-situ DRIFTs and density functional theory calculations. It revealed that Ce did not alter the reaction mechanism, but promoted the adsorption and activation of gaseous O2 on the catalyst surface. Overall, this study will provide more new insights into the catalytic mechanism of volatile organic compounds catalytic oxidation.

The metal-semiconductor interface fabricated by conventional methods often suffers from contamination, degrading transport performance. Herein, we propose a one-pot chemical vapor deposition (CVD) process to create a two-dimensional (2D) MoO2-MoSe2 heterostructure by growing MoO2 seeds under a hydrogen environment, followed by depositing MoSe2 on the surface and periphery. The ultraclean interface is verified by cross-sectional scanning transmission electron microscopy and photoluminescence. Along with the high work function of semimetallic MoO2 (E-f = -5.6 eV), a high-rectification Schottky diode is fabricated based on this heterostructure. Furthermore, the Schottky diode exhibits an excellent photovoltaic effect with a high open-circuit voltage of 0.26 eV and ultrafast photoresponse, owing to the naturally formed metal-semiconductor contact with suppressed pinning effect. Our method paves the way for the fabrication of an ultraclean 2D metal-semiconductor interface, without defects or contamination, offering promising prospects for future nanoelectronics.

AbstractThe design of high‐entropy single‐atom catalysts (HESAC) with 5.2 times higher entropy compared to single‐atom catalysts (SAC) is proposed, by using four different metals (FeCoNiRu‐HESAC) for oxygen reduction reaction (ORR). Fe active sites with intermetallic distances of 6.1 Å exhibit a low ORR overpotential of 0.44 V, which originates from weakening the adsorption of OH intermediates. Based on density functional theory (DFT) findings, the FeCoNiRu‐HESAC with a nitrogen‐doped sample were synthesized. The atomic structures are confirmed with X‐ray photoelectron spectroscopy (XPS), X‐ray absorption (XAS), and scanning transmission electron microscopy (STEM). The predicted high catalytic activity is experimentally verified, finding that FeCoNiRu‐HESAC has overpotentials of 0.41 and 0.37 V with Tafel slopes of 101 and 210 mVdec−1 at the current density of 1 mA cm−2 and the kinetic current densities of 8.2 and 5.3 mA cm−2, respectively, in acidic and alkaline electrolytes. These results are comparable with Pt/C. The FeCoNiRu‐HESAC is used for Zinc–air battery applications with an open circuit potential of 1.39 V and power density of 0.16 W cm−2. Therefore, a strategy guided by DFT is provided for the rational design of HESAC which can be replaced with high‐cost Pt catalysts toward ORR and beyond.

Metal batteries using lithium, sodium, potassium, zinc, etc., as anodes have garnered tremendous attention in rechargeable batteries because of their highly desirable theoretical energy densities. However, large-scale application of these metal batteries is impeded by dendrite growth on the anode surface, which may penetrate the separator, leading to battery failure. Two dimensional (2D) materials featured by excellent mechanical strength and flexibility, tunable electronic properties and controllable assembly are promising materials for the construction of dendrite-free metal batteries. In this review, we summarize recent advancements of 2D materials for their potential use in critical components of dendrite-free batteries used as: (1) a host or artificial solid-electrolyte for metal anodes; (2) a solid electrolyte or modifier for electrolyte; and (3) an enhancement component for separators design. We conclude that 2D materials hold great promise for tackling the problems associated with dendrite formation by functioning as mechanical reinforcement and metal deposition regulators, along with improved safety, performance, and durability of batteries. Finally, this review discusses new perspectives and future directions in the field of 2D materials towards safe, high-energy metal batteries.

A new reactive force field based on quantum mechanical data for describing formation of the Zn electrode-electrolyte interface (EEI) chemistry in aqueous zinc-ion batteries (ZIBs) is developed. This is the first demonstration in which Reactive Molecular Dynamics (RMD) simulation is used to follow the Zn reduction and anode structural evolution at the EEI. It is found that under axial pressure, Zn dendrite formation is inhibited. This is associated with accelerated ion transport and reduction while increasing preference towards horizontal (002) plane growth. Pressure-induced desolvation of Zn ions within the electric double layer, which promotes faster reduction kinetics is observed. It is found that axial pressure stabilizes adatoms on the (002) plane by decreasing axial atom stress during nucleation and by increasing favorable lateral adatom diffusion, which reduces atomic scale dendrite formation. Finally, these are confirmed results by experimental characterization and electrochemical tests. Zn electroplating process includes ions transportation, reduction, and nucleation. However, the competition among Zn2+ diffusion, reduction kinetics, and crystallographic thermodynamics, remains ambiguous. The powerful computational tool, Reactive Molecular Dynamics simulation, is used to describe the movement, reactions, and nucleation during dynamics at the atomic scale to gain a thorough understanding of the atomistic interface environment and the origin of Zn dendrite formation.image

We provide the rational design of dual atom catalysts (DACs) supported on nitrogen-doped graphene for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through high-throughput computational screening of M(1)M(2)N6-DAC systems, where M-1 and M-2 represent Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, or Pt metals. We predict that FeRuN6-DAC at the summit of the volcano plot exhibits a low theoretical ORR overpotential (eta(ORR)) of 0.24 V and a low theoretical OER overpotential (eta(OER)) of 0.19 V. The low eta(ORR) and eta(OER) result from the catalytic performance of the Fe site being tuned to electronic properties that facilitate adsorption and desorption of the OH* intermediate. Inspired by these hybrid density functional theory (DFT) computational and machine learning (ML) results, we synthesized FeRuN6-DAC, FeN4-SAC, and RuN4-SAC and characterized them using Xray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and in-situ electron spin resonance (ESR). Our in-situ ESR spectroscopy signifies that the spin of the Fe active site increases with increasing applied potential due to the increase in the concentration of OH* intermediate on Fe. We verified experimentally the predicted catalytic performances, finding that FeRuN6-DAC leads to an experimental ORR overpotential of 0.29 V with a Tafel slope of 104 mVdec(-1) and an OER overpotential of 0.27 V with a Tafel slope of 124 mVdec(-1). The rechargeable Zinc-air battery setup was fabricated with FeRuN6-DAC in place of the cathode, showing a maximum power density of 0.45 W/cm(2) at the current density of 0.44 A/cm(2) and good stability after 120 cycles. According to our findings, we demonstrate that DFTguided strategies are useful for designing advanced DACs applicable to ORR, OER, and Zinc-air battery applications.

Monolayer and large area hBN as an artificial SEI layer shows dual role in preventing the undesired side reaction of HER and inducing the heteroepitaxial grown of Zn, successfully resolving the dendrite issue for safe Zn metal anode.

Aprotic lithium-oxygen batteries (LOBs) have been considered as one of the next-generation battery technologies, due to its ultrahigh theoretical energy density (~3600 Wh kg -1), 5-10 times higher than the state-of-the-art lithium-ion batteries (LIBs), supporting the development of electric vehicles (EVs). However, the battery system suffers from poor cyclability, low round-trip efficiency and inferior rate capability, mainly originated from the inertness of oxygen gas and the poor electrical conductivity of lithium peroxide (Li2O2), leading to the sluggish kinetics of oxygen reduction reaction (ORR)/ oxygen evolution reaction (OER). In response to the challenges, developing a highly efficient catalyst at the cathode is vital to boost the reaction rate and reduce the reaction overpotentials, eventually address the problem. Heterogeneous single-atom catalysts (SACs) on solid support are emerging as a new frontier in this research field. Here, we use the density of state (DFT) calculation to determine the catalytic activities of a wide range of transition metal single atoms distributing on the nitrogen doped graphene support and found that Zn-SAC exhibits the highest ORR/OER activities. We discovered that Zn-N4 moieties, functioning as catalytic centers, bind with LiO2 not very strongly, reduce the reaction overpotentials, facilitates the reaction rate and enhance the stability of the catalyst. The catalytic activity of SACs is highly correlated to the Gibbs free energy of the adsorbed LiO2. A descriptor, F of the catalysts determining the catalytic activity was developed from the metal properties of electronegativity (EN), enthalpy of vaporization (EV) and number of electrons in d orbital, by using supervised machine learning (ML) method, providing guidance for designing useful SACs in ORR/OER process. This work systematically provides guidance to design highly efficient SAC for LOBs and provides fundamental insights in choosing the proper metal for the ORR/ OER application.

With a high specific capacity and low electrochemical potentials, metal anode batteries that use lithium, sodium and zinc metal anodes, have gained great research interest in recent years, as a potential candidate for high-energy-density storage systems. However, the uncontainable dendrite growth during the repeated charging process, deteriorates the battery performance, reduces the battery life and more importantly, raises safety concerns. With their unique properties, two-dimensional (2D) materials, can be used to modify various components in metal batteries, eventually mitigating the dendrite growth, enhancing the cycling stability and rate capability, thus leading to safe and robust metal anodes. In this paper, we review the recent advances of 2D materials and summarize current research progress of using 2D materials in the applications of (i) anode design, (ii) separator engineering, and (iii) electrolyte modifications by guiding metal ion nucleation, increasing ion conductivity, homogenizing the electric field and ion flux, and enhancing the mechanical strength for safe metal anodes. The 2D material modifications provide the ultimate solution for obtaining dendrite-free metal anodes, realizes the high energy storage application, and indicates the importance of 2D materials development. Finally, in-depth understandings of subsequent metal growth are lacking due to research limitations, while more advanced characterizations are welcome for investigating the metal deposition mechanism. The more facile and simplified preparation of 2D materials possess great prospects in high energy density metal anode batteries, and thus fulfils the development of EVs.

The practical application of naturally abundant sodium (Na) metal anodes with high energy densities is hindered by large volume expansion and dendrite formation during battery operation. This work reports the synthesis of tin selenide nanoparticles uniformly grown on highly conductive, porous 3D graphene foam (SnSe@GF) as a stable host for Na metal anodes and the underlying conversion reactions as their energy storage mechanism. The SnSe@GF electrode prepared via hydrogel coating and phase transformation sustains remarkable reversibility after 1500 cycles in asymmetric cells and delivers extraordinary cyclic stability and low overpotentials for 2000 h at 1 mA cm-2 and 1 mAh cm-2 in symmetric cells. The conversion of crystalline SnSe into low-crystallinity Na15Sn4 and Na2Se dual nucleation sites after pre-sodiation is responsible for the outstanding performance according to the in-situ microscopy and density functional theory calculations. The conversion enables the in-situ formation of a unique interface that possesses high Na affinity featured by abundant active sites, contributing to uniform Na nucleation/plating and dendrite suppression, thus give rising to superior stability and electrochemical performance of the SnSe@GF electrode. The rational design of the current 3D architecture can shed new insights into the development of Na hosts for next-generation rechargeable batteries.

Atomically thin monolayer semiconducting transition metal dichalcogenides (TMDs), exhibiting direct band gap and strong light-matter interaction, are promising for optoelectronic devices. However, an efficient band alignment engineering method is required to further broaden their practical applications as versatile optoelectronics. In this work, the band alignment of two vertically stacked monolayer TMDs using the chemical vapor deposition (CVD) method is effectively tuned by two strategies: 1) formulating the compositions of MoS2(1-x)Se2x alloys, and 2) varying the twist angles of the stacked heterobilayer structures. Photoluminescence (PL) results combined with density functional theory (DFT) calculation show that by changing the alloy composition, a continuously tunable band alignment and a transition of type II-type I-type II band alignment of TMD heterobilayer is achieved. Moreover, only at moderate (10 degrees-50 degrees) twist angles, a PL enhancement of 28%-110% caused by the type I alignment is observed, indicating that the twist angle is coupled with the global band structure of heterobilayer. A heterojunction device made with MoS0.76Se1.24/WS2 of 14 degrees displays a significantly high photoresponsivity (55.9 A W-1), large detectivity (1.07 x 10(10) Jones), and high external quantum efficiency (135%). These findings provide engineering tools for heterostructure design for their application in optoelectronic devices.

Crystal plane effect has attracted remarkable attention in the process of peroxymonosulfate (PMS) activation in water. In this work, nanocube-Co3O4 (Co3O4-NC), nanoplate-Co3O4 (Co3O4-NP) and nanorod-like Co3O4 (Co3O4-NR) with (100), (111) and (110) plane predominant exposure is prepared by a facile hydrothermal method. Co3O4-NR with (110) plane exposed possesses more lattice defects (oxygen vacancies, Ov) and low oxidation state Co (Co2+), consequently, it exhibits a superior activity for PMS activation to efficiently remove bisphenol A (BPA) in water. Furthermore, it could be used in a widely water pH values ranging from 5.0 to 9.0 with an excellent PMS activited effects. During Co3O4-NR/PMS oxidation process, it is found that singlet oxygen (1O2) plays a dominant role in BPA degradation. However, Co3O4-NR treated by H2O2 shows a poor PMS activation performance, confirming Ov acting as the active site during such oxidation process. The important effect of dissolved oxygen is tested by Ar introduction into the reaction system and the Ov-O* metastable intermediate is proposed. In situ Raman proves the interaction between dissolved oxygen and Ov and then the intermediate activates PMS to degrade BPA. This work not only explores the effect of different crystal plane exposures on PMS activation in Co3O4/PMS system, but investigates the evolution of Ov during the PMS activation.

Lateral superlattices have been a research focus due to the strain induced intheir coherent structure, while the growth of a large size heterostructure with high densityof heterointerfaces remains challenging. In this work, we report a gap-filling approach tosynthesize large-scale lateral mesh heterostructures of WS2embedded in a MoS2matrix.This synthesis method utilizes the uniformly distributed gaps in single crystalline MoS2,made by the sulfur substitution-induced transformation of metastable-MoTe2as thegrowth pattern, for the second material growth. Byfinely controlling the growth kinetics, ahighly crystalline WS2/MoS2lateral heterostructure mesh is successfully grown. Opticalimages and Raman mapping show a clear spatial distribution of WS2channels embedded in MoS2. The coherent epitaxial nature isfurther confirmed by scanning transmission electron microscopy, showing insignificant dislocation at the interfaces. Density functiontheory simulation suggests that the growth of WS2starts from the edges of cracked MoS2. The MoS2/WS2/MoS2heterostructuredevice demonstrates an intrinsic electric barrier formed at the interfaces. This work provides a new tool for the practical preparationof large-scale high density 2D heterostructures.

Owing to the moderate redox potential and high safety, Zn metal anodes have been garnering great attention. However, the poor reversibility and limited‐service period caused by side reactions and dendrites hinder their applications. Here, a novel anode material consisting of a hexagonal 1T‐Vanadium diselenide (1T‐VSe 2 ) film on graphene is developed as a zincophilic template to epitaxially electrodeposit hexagonal closest packed Zn to replace the conventional metal substrates in Zn batteries. The 1T‐VSe 2 /Zn anode induces a horizontally (002)‐oriented plate‐like Zn crystal deposition morphology instead of randomly oriented grains that prompts the compact Zn deposition. According to density functional theory calculations, the VSe 2 substrate exhibits a higher Zn adsorption (−0.54 eV) than the graphene (−0.38 eV) or neat Zn (−0.48 eV) counterparts, leading to the enhanced zincophilicity and a lower nucleation overpotential, in agreement with the experimental results. The force field‐based molecular dynamics simulations visualize Zn nucleation and morphological evolution at the atomistic level. The rapid adatom diffusion on VSe 2 leads to layer‐by‐layer Zn electrodeposits with higher fraction of the (002) facets to effectively prohibit dendrite formation. The symmetric cell with 1T‐VSe 2 /Zn delivers an ultra‐stable cyclic life of 2500 h with 50 mV overpotential at 1 mA cm −2 and 1 mAh cm −2 .

The extremely large surface area offered by quasi-two-dimensional (2D) nanostructures is a great advantage for catalytic applications. While bimetallic materials have been discovered as a group of promising catalysts for electrochemical water splitting, a facile and reliable synthesis approach toward 2D morphology to fully release its electrochemical catalytic potential is still lacking. In this work, bimetallic Co-Mo-O ultrathin nanosheets were synthesized by ionic layer epitaxy with controlled composition ratio. The Co-Mo-O nanosheets exhibited a quadrangle shape with a uniform thickness of similar to 2.5 nm. This 2D morphology largely enriched the surface catalytic active site ratio. Particularly, nanosheets with 2:1 Co-to-Mo ratio showed a substantially enhanced OER catalytic activity with a 3 orders of magnitude higher mass activity compared to benchmark IrO2 and RuO2 in an alkaline environment. This study introduces a promising possibility for creating high-performance electrocatalysts from 2D bimetallic materials with a high efficiency for material utilization.