Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing units.In response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these limitations.Memristive devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological synapses.Among these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form heterojunctions.This review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential applications.Furthermore,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential solutions.The primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

Thermal properties of transition-metal dichalcogenide

Beyond graphene, the layered transition metal dichalcogenides （TMDs） have gained considerable attention due to their unique properties. Herein, we review the lattice dynamic and thermal properties of monolayer TMDs, including their phonon dispersion, relaxation time, mean free path （MFP）, and thermal conductivities. In particular, the experimental and theoretical studies reveal that the TMDs have relatively low thermal conductivities due to the short phonon group velocity and MFP, which poses a significant challenge for efficient thermal management of TMDs-based devices. Importantly, recent studies have shown that this issue could be largely addressed by connecting TMDs and other materials （such as metal electrode and graphene） with chemical bonds, and a relatively high interracial thermal conductance （ITC） could be achieved at the covalent bonded interface. The ITC of MoS2/Au interface with chemical edge contact is more than 10 times higher than that with physical side contact. In this article, we review recent advances in the study of TMD-related ITC. The effects of temperature, interfacial vacancy, contact orientation, and phonon modes on the edge-contacted interface are briefly discussed.

UV Photodissociation Dynamics of Nitric Acid： The Hydroxyl Elimination Channel

Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.

Breakup of spherical vesicles caused by spontaneous curvature change

We present our theoretical analysis and coarse- grained molecular dynamics （CGMD） simulation results to describe the mechanics of breakup of spherical vesi- cles driven by changes in spontaneous curvature. System- atic CGMD simulations reveal the phase diagrams for the breakup and show richness in breakup morphologies. A the- oretical model based on Griffith fracture mechanics is devel- oped and used to predict the breakup condition.

Frameworked electrolytes:Ionic transport behavior and high mobility for solid state batteries

All solid-state batteries(ASSBs)are the holy grails of rechargeable batteries,where extensive searches are ongoing in the pursuit of ideal solid-state electrolytes.Nevertheless,there is still a long way off to the satisfactorily high(enough)ionic conductivity,long-term stability and especially being able to form compatible interfaces with the solid electrodes.Herein,we have explored ionic transport behavior and high mobility in the sub-nano pore networks in the framework structures.Macroscopically,the frameworked electrolyte behaves as a solid,and however in the(sub)-nano scales,the very limited number of solvent molecules in confinement makes them completely different from that in liquid electrolyte.Differentiated from a liquid-electrolyte counterpart,the interactions between the mobile ions and surrounding molecules are subject to dramatic changes,leading to a high ionic conductivity at room temperature with a low activation energy.Li+ions in the sub-nano cages of the network structure are highly mobile and diffuse rather independently,where the rate-limiting step of ions crossing cages is driven by the local concentration gradient and the electrostatic interactions between Li^(+)ions.This new class of frameworked electrolytes(FEs)with both high ionic conductivity and desirable interface with solid electrodes are demonstrated to work with Li-ion batteries,where the ASSB with LiFePO_(4)shows a highly stable electrochemical performance of over 450 cycles at 2℃ at room temperature,with an almost negligible capacity fade of 0.03‰ each cycle.In addition,the FE shows outstanding flexibility and anti-flammability,which are among the key requirements of large-scale applications.

通过表面终止化学设计实现高度可逆的锌金属阳极

锌表面自然形成的非均匀氧化层(ZnO)会与电解液发生反应形成Zn_(4)(OH)_(6)SO_(4)·xH_(2)O(ZSH)副产物,导致锌负极表面非均匀沉积,从而阻碍水性锌离子电池实际应用.为了排除氧化层分布形式的影响,本文利用表面终止化学设计策略在锌负极表面制备了一层完全氧化的ZnO层,研究发现锌负极均匀分布的ZnO层会原位演化形成致密的ZSH功能层.均匀且致密的ZSH能够有效隔绝电解液的腐蚀,从而有效提高锌负极界面的稳定性.此外,ZSH(002)晶面边缘的不饱和悬空键(如-O)更容易和Zn(H_(2)O)_(6)^(2+)结构中的锌离子形成强Zn-O键,可以促进Zn(H_(2)O)_(6)^(2+)的脱溶剂化和锌离子沿边扩散,实现了高度可逆的锌沉积行为并限制了副反应.基于此,本文提出与“表面脱水-晶体通道转移”机制明显不同的“边缘脱水-沿边缘转移”锌离子输运新机制.更重要的是,基于此组装的全电池显示出高循环稳定性(超过1000次循环)和高库仑效率(99.07%),验证了其潜在的实际应用价值.

Strain-tunable electronic and transport properties of MoS2 nanotubes

Using density functional theory calculations, we have investigated the mechanical properties and strain effects on the electronic structure and transport properties of molybdenum disulfide （MoS2） nanotubes. At a similar diameter, an armchair nanotube has a higher Young＇s modulus and Poisson ratio than its zigzag counterpart due to the different orientations of Mo-S bond topologies. An increase in axial tensile strain leads to a progressive decrease in the band gap for both armchair and zigzag nanotubes. For armchair nanotube, however, there is a semiconductor-to-metal transition at the tensile strain of about 8%. For both armchair and zigzag nanotubes, the effective mass of a hole is uniformly larger than its electron counterpart, and is more sensitive to strain. Based on deformation potential theory, we have calculated the carrier mobilities of MoS2 nanotubes. It is found that the hole mobility is higher than its electron counterpart for armchair （6, 6） nanotube while the electron mobility is higher than its hole counterpart for zigzag （10, 0） nanotube. Our results highlight the tunable electronic properties of MoS2 nanotubes, promising for interesting applications in nanodevices, such as opto-electronics, photoluminescence, electronic switch and nanoscale strain sensor.

Supramolecular gating of guest release from cucurbit[7]uril using de novo design

Herein we computationally explore the modulation of the release kinetics of an encapsulated guest molecule from the cucurbit[7]uril(CB7)cavity by ligands binding to the host portal.We uncovered a correlation between the ligand-binding affinity with CB7 and the guest residence time,allowing us to rapidly predict the release kinetics through straightforward energy minimization calculations.These high-throughput predictions in turn enable a Monte-Carlo Tree Search(MCTS)to de novo design a series of cap-shaped ligand molecules with large binding affinities and boosting guest residence times by up to 7 orders of magnitude.Notably,halogenated aromatic compounds emerge as top-ranking ligands.Detailed modeling suggests the presence of halogen-bonding between the ligands and the CB7 portal.Meanwhile,the binding of top-ranked ligands is supported by^(1)H NMR and 2D DOSY-NMR.Our findings open up possibilities in gating of molecular transport through a nanoscale cavity with potential applications in nanopore technology and controlled drug release.

Origin of ultrafast growth of monolayer WSe_(2) via chemical vapor deposition

The ultrafast growth of large-area,high-quality WSe2 domains with a compact triangular morphology has recently been achieved on a gold substrate via chemical vapor deposition.However,the underlying mechanism responsible for ultrafast growth remains elusive.Here,we first analyze growth processes and identify two possible pathways that might achieve ultrafast growth:Path 1,fast edge attachment and ultrafast edge diffusion;Path 2,fast kink nucleation and ultrafast kink propagation.We perform kinetic Monte Carlo simulations and first-principles calculations to assess the viability of these two paths,finding that Path 1 is not viable due to the high edge diffusion barrier calculated from first-principles calculations.Remarkably,Path 2 reproduces all the experimental growth features(domain morphology,domain orientation,and growth rate),and the associated energetic data are consistent with first-principles calculations.The present work unveils the underlying mechanism for the ultrafast growth of WSe2,and may provide a new route for the ultrafast growth of other two-dimensional materials.