Integrated Interfacial Modulation Strategy: Trace Sodium Hydroxyethyl Sulfonate Additive for Extended-Life Zn Anode Based on Anion Adsorption and Electrostatic Shield.

Aqueous zinc-ion batteries (AZIBs) are poised to play a pivotal part in meeting the growing demands for energy storage and powering portable electronics for their superior security, affordability, and environmentally friendly characteristics. However, the detrimental side reactions occurring at the zinc anode and the dendrite caused by uneven zinc plating/stripping have greatly compromised the cycling life of AZIBs, thereby impeding their practical prospects. In this study, the interfacial comodulation strategy was employed by combining the "electrostatic shielding" effect of cations with the characteristic adsorption of anions. Two molar ZnSO4 served as the matrix, and sodium hydroxyethyl sulfonate (SHES) was selected as a low-cost, nontoxic additive. Experimental results confirm that SHES and zinc anode exhibit robust interactions that lead to the formation of an electrostatic shield and a dynamic adsorption layer at the interface, thereby suppressing hydrogen evolution and corrosion. The combined "electrostatic shielding" effect of sodium ions and the robust characteristic adsorption of hydroxyethyl sulfonate anions serve to guide the directed three-dimensional (3D) diffusion of Zn2+, facilitating rapid, stable, and uniform deposition of zinc. Due to these effects, incorporating 0.2 M SHES as an additive extends the cycle life beyond 3600 h and enables a highly reversible process of deposition and stripping in symmetric cells. Additionally, the Zn-Cu half-cell exhibits reliable cycling for over 1400 cycles, achieving an average Coulombic efficiency of 99.6%. Moreover, the introduction of this additive substantially enhances the performance of Zn-MnO2 and Zn-NH4V4O10 full cells. This study demonstrates the practical feasibility of achieving anodes with high reversibility in AZIBs through the implementation of a strategy that involves anion adsorption at the interface, which holds paramount significance for the practical application of AZIBs.

Overcoming challenges of protonation effects induced by high isoelectric point amino acids through a synergistic strategy towards highly stable and reversible zinc electrode-electrolyte interface.

Amino acids are among the most commercially promising additive solutions for achieving stable zinc anodes. However, greater attention should be given to the limitation arising from the protonation effects induced by high isoelectric point amino acids in the weakly acidic electrolytes of aqueous zinc-ion batteries (AZIBs). In this study, we introduce histidine (HIS) and ethylenediaminetetraacetic acid (EDTA) as hybrid additives into the aqueous electrolyte. Protonated HIS is adsorbed onto the anode interface, inducing uniform deposition and excluding H2O from the inner Helmholtz plane (IHP). Furthermore, the addition of EDTA compensates for the limitation of protonated HIS in excluding solvated H2O. EDTA reconstructs the solvation structure of Zn2+, resulting in a denser zinc deposition morphology. The results demonstrate that the Zn||Zn battery achieved a cycling lifespan exceeding 1480 h at 5 mA cm-2 and 5 mAh cm-2. It also reached over 900 h of cycling at a zinc utilization rate of 70 %. This study provides an innovative perspective for advancing the further development of AZIBs.

Estimation of the Band Gap of Carbon Nanotube Bundles.

The electronic structure of carbon nanotube bundles (CNTBs) can be a tough task for the routine first-principle calculation. The difficulty comes from several issues including the atomic structure, the boundary condition, and above all the very large number of atoms that makes the calculation quite cumbersome. In this work, we estimated the band gap of the CNTBs based on the results from single-walled carbon nanotubes (SWCNTs) under different deformations. The effects of squeezing, stretching, and torsion on the bands of SWCNTs were investigated through first-principle calculations, from which the band gaps of bundles were analyzed because the effects of these deformations were qualitatively independent when the distortions were small. Specifically, the gaps of (4,4) and (8,0) CNTBs under a reasonable torsional strength were predicted, wherein we were able to see metal-semiconductor and semiconductor-metal transitions, respectively. Such reversible mechanical modification of the conductivity may be helpful to the future band-gap engineering in nanoscale circuits.

Overcoming Challenges: Extending Cycle Life of Aqueous Zinc-Ion Batteries at High Zinc Utilization through a Synergistic Strategy.

Aqueous zinc-ion batteries (AZIBs) face challenges in achieving high energy density compared to conventional lithium-ion batteries (LIBs). The lower operating voltage and excessive Zn metal as anode pose constraints on the overall energy storage capacity of these batteries. An effective approach is to reduce the thickness of the Zn metal anode and control its mass appropriately. However, under the condition of using a thin Zn anode, the performance of AZIBs is often unsatisfactory. Through experiments and computational simulations, the electrode structural change and the formation of dead Zn as the primary reasons for the failure of batteries under a high Zn utilization rate are identified. Based on this understanding, a universal synergistic strategy that combines Cu foil current collectors and electrolyte additives to maintain the structural and thermodynamic stability of the Zn anode under a high Zn utilization rate (ZUR) is proposed. Specifically, the Cu current collectors can ensure that the Zn anode structure remains intact based on the spontaneous filling effect, while the additives can suppress parasitic side reactions at the interface. Ultimately, the symmetric cell demonstrates a cycling duration of 900 h at a 70% ZU, confirming the effectiveness of this strategy.

First principle calculation of the photocurrent in a short carbon nanotube: the effect of an external bias.

We studied the transport properties of a short carbon nanotube between two different metal electrodes. Specifically, the photocurrents under a series of bias voltages are investigated. The calculations are completed within the non-equilibrium Green's function method, where the photon-electron interaction is taken as a perturbation. The rule-of-thumb that a forward bias decreases while a reverse bias increases the photocurrent under the same illumination is verified. The first principle results demonstrate the characteristic of the Franz-Keldysh effect, where the photocurrent response edge shows a clear red-shift trend in electric fields along both axial directions. An obvious Stark splitting is observed when some reverse bias is applied to the system due to the huge field strength. In this short-channel situation, intrinsic nanotube states are strongly hybridized with metal electrode states, which results in dark current leakage and specific features such as a long tail and fluctuations in the photocurrent response.

Substituent-mediated quantum interference toward a giant single-molecule conductance variation.

Quantum interference (QI) in single molecular junctions shows a promising perspective for realizing conceptual nanoelectronics. However, controlling and modulating the QI remains a big challenge. Herein, two-type substituents at different positions ofmeta-linked benzene, namely electron-donating methoxy (-OMe) and electron-withdrawing nitryl (-NO2), are designed and synthesized to investigate the substituent effects on QI. The calculated transmission coefficientsT(E) indicates that -OMe and -NO2could remove the antiresonance and destructive quantum interference (DQI)-induced transmission dips at position 2. -OMe could raise the antiresonance energy at position 4 while -NO2groups removes the DQI features. For substituents at position 5, both of them are nonactive for tuning QI. The conductance measurements by scanning tunneling microscopy break junction show a good agreement with the theoretical prediction. More than two order of magnitude single-molecule conductance on/off ratio could be achieved at the different positions of -NO2substituent groups at room temperature. The present work proves chemical substituents can be used for tuning QI features in single molecular junctions, which provides a feasible way toward realization of high-performance molecular devices.

Acoustic graphene plasmon resonator based on gold nanowire arrays.

An acoustic graphene plasmon (AGP) resonator based on gold nanowire arrays structure is proposed in this paper. The resonator is designed by continuous graphene layer/gold nanowire arrays/optical resonant cavity. The infrared light excites the AGP in the graphene/gold arrays structure and propagates along the graphene surface. The coupling efficiency can be improved by the optical resonator cavity. The finite-difference time-domain method is used to simulate and optimize the property of the resonator. The results show that the resonator has a stronger optical limiting effect and higher coupling efficiency. The AGPs are a prospective platform that enhances light-matter interactions, reduces spread loss, and exhibits a double resonance absorption phenomenon in the studied mid-infrared wavelength range. The research results provide a basis for the design of optoelectronic devices and more.

A supply chain disruption recovery strategy considering product change under COVID-19.

A recent global outbreak of Corona Virus Disease 2019 (COVID-19) has led to massive supply chain disruption, resulting in difficulties for manufacturers on recovering their supply chains in a short term. This paper presents a supply chain disruption recovery strategy with the motivation of changing the original product type to cope with that. In order to maximize the total profit from product changes, a mixed integer linear programming (MILP) model is developed with combining emergency procurement on the supply side and product changes by the manufacturer as well as backorder price compensation on the demand side. The model uses a heuristic algorithm based on ILOG CPLEX toolbox. Experimental results show that the proposed disruption recovery strategy can effectively reduce the profit loss of manufacturer due to late delivery and order cancellation. It is observed that the impact of supply chain disruptions is reduced. The proposed model can offer a potentially useful tool to help the manufacturers decide on the optimal recovery strategy whenever the supply chain system experiences a sudden massive disruption.

z-Piezo Pulse-Modulated STM Break Junction: Toward Single-Molecule Rectifiers with Dissimilar Metal Electrodes.

Fabricating single-molecule junctions with asymmetric metal electrodes is significant for realizing single-molecule diodes, but it remains a big challenge. Herein, we develop a z-piezo pulse-modulated scanning tunneling microscopy break junction (STM-BJ) technique to construct a robust asymmetric junction with different metal electrodes. The asymmetric Ag/BPY-EE/Au single-molecule junctions exhibit a middle conductance value in between those of the two individual symmetric metal electrode junctions, which is consistent with the order of calculated energy-dependent transmission coefficient T(E) of the asymmetric junctions at EF. Furthermore, the single-molecule conductance of Ag/BPY-EE/Au decreases by about 70% when reversing the bias voltage from 100 to -100 mV, and a clear asymmetric I-V feature at the single-molecule level is observed for these junctions. This rectifying behavior could be ascribed to a different interfacial coupling of molecules at the two end electrodes, which is confirmed by the different displacement of T(E) at the two bias voltages. Other asymmetric junctions exhibit similar rectifying behavior. The current work provides a feasible way to fabricate hybrid junctions based on asymmetric metal electrodes and investigate their electron transport toward the design of molecular rectifiers.

Enhanced Gating Performance of Single-Molecule Conductance by Heterocyclic Molecules.

Enhancing the gating performance of single-molecule conductance is significant for realizing molecular transistors. Herein, we report a new strategy to improve the electrochemical gating efficiency of single-molecule conductance with fused molecular structures consisting of heterocyclic rings of furan, thiophene, or selenophene. One order magnitude of gating ratio is achieved within a potential window of 1.2 V for the selenophene-based molecule, which is significantly greater than that of other heterocyclic and benzene ring molecules. This is caused by the different electronic structures of heterocyclic molecules and transmission coefficients T(E), and preliminary resonance tunneling is achieved through the highest occupied molecular orbital at high potential. The current work experimentally shows that electrochemical gating performance can be significantly modulated by the alignment of the conducting orbital of the heterocyclic molecule relative to the metal Fermi energy.

Controlling Contact Configuration of Carboxylic Acid-Based Molecular Junctions Through Side Group.

In this paper, the contact configuration of single molecular junction is controlled through side group, which is explored by electrochemical jump-to-contact STM break junction. The conductance values of 2-methoxy-1,3-benzenedicarboxylic acid (2-M-1,3-BDC) is around 10-3.65 G0, which is different from that of 5-methoxy-1,3-benzenedicarboxylic acid (5-M-1,3-BDC) with 10-3.20 G0. Interestingly, the conductance value of 2-M-1,3-BDC is the same as that of 1,3-benzenedicarboxaldehyde (1,3-BDCA), while single molecular junctions of 5-M-1,3-BDC and 1,3-benzenedicarboxylic acid (1,3-BDC) give out similar conductance value. Since 1,3-BDCA binds to the Cu electrode through one oxygen atom, the dominated contact configuration for 1,3-BDC is through two oxygen atoms. The different conductance values between 2-M-1,3-BDC and 5-M-1,3-BDC can be attributed to the different contact configurations caused by the position of the side group. The current work provides a feasible way to control the contact configuration between the anchoring group and the electrode, which may be useful in designing future molecular electronics.

Anomalous and Polarization-Sensitive Photoresponse of Td -WTe2 from Visible to Infrared Light.

Recently, an emergent layered material Td -WTe2 was explored for its novel electron-hole overlapping band structure and anisotropic inplane crystal structure. Here, the photoresponse of mechanically exfoliated WTe2 flakes is investigated. A large anomalous current decrease for visible (514.5 nm), and mid- and far-infrared (3.8 and 10.6 µm) laser irradiation is observed, which can be attributed to light-induced surface bandgap opening from the first-principles calculations. The photocurrent and responsivity can be as large as 40 µA and 250 A W-1 for a 3.8 µm laser at 77 K. Furthermore, the WTe2 anomalous photocurrent matches its in-plane crystal structure and exhibits light polarization dependence, maximal for linear laser polarization along the W atom chain a direction and minimal for the perpendicular b direction, with the anisotropic ratio of 4.9. Consistently, first-principles calculations confirm the angle-dependent bandgap opening of WTe2 under polarized light irradiation. The anomalous and polarization-sensitive photoresponses suggest that linearly polarized light can significantly tune the WTe2 surface electronic structure, providing a potential approach to detect polarized and broadband lights up to far infrared range.

Controlling and Observing Sharp-Valleyed Quantum Interference Effect in Single Molecular Junctions.

The ability to control over the quantum interference (QI) effect in single molecular junctions is attractive in the application of molecular electronics. Herein we report that the QI effect of meta-benzene based molecule with dihydrobenzo[ b]thiophene as the anchoring group ( meta-BT) can be controlled by manipulating the electrode potential of the junctions in electrolyte while the redox state of the molecule does not change. More than 2 orders of magnitude conductance change is observed for meta-BT ranging from <10-6.0 to 10-3.3 G0 with varying the electrode potential, while the upper value is even larger than the conductance of para-BT ( para-benzene based molecule with anchoring group of dihydrobenzo[ b]thiophene). This phenomenon is attributed to the shifting of energy level alignment between the molecule and electrodes under electrode potential control. Calculation is carried out to predict the transmission function of single molecular junction and the work function of Au surface in the presence of the molecule, and good agreement is found between theory and experiments, both showing sharp-valley featured destructive QI effect for the meta-BT. The present work demonstrates that the QI effect can be tuned through electrochemical gating without change of molecular redox states, which provides a feasible way toward realization of effective molecular switches.

A proposal of a spin cell using light on magnetic tunneling junctions.

We propose and theoretically investigate a spin cell using light as the power source. Such a device can be realized when a quantum dot is connected to two ferromagnetic electrodes. In the case of identical electrodes, a pure spin current (PSC) can be generated when the light is shone on the quantum dot. Moreover, the PSC can be tuned continuously from zero to the maximum when the magnetic moment orientations of the two electrodes are changed from parallel to anti-parallel. The output spin bias is linear with the light power in the low power region, while it approaches the theoretical limit when the power is extremely high because of the electrodes' renormalization by the spin transfer torque. This effect implies that light energy can be transferred to electron spin directly, which may be applicable in future opto-spintronics.