•The influence of solute elements and chlorine adsorption on the anodic behavior of Mg (0001) surface is investigated based on work function change and local electrode potential shift.•Li, Al, Mn, ...Zn, Fe, Ni, Cu, Y, and Zr are considered as solute atoms in this work.•Cl adsorbate will destabilize Mg atoms on the surface by weakening the metal bonds.•Strong hybridization between Mg and solute atom orbitals will raise the local electrode potential.
Solute atoms and Cl adsorbate at Mg(0001) surface may change the work function and local electrode potential and further influence the anodic behavior of Mg matrix. Display omitted
The influences of solute atoms (Li, Al, Mn, Zn, Fe, Ni, Cu, Y, Zr) and Cl adsorption on the anodic corrosion performance on Mg (0001) surface have been investigated based on first-principles calculations, which might be useful for the design of corrosion-resistant Mg alloys. Work function and local electrode potential shift are chosen as descriptors since they quantify the barrier for charge transfer and anodic stability. We found that at 25% surface doping rate, Y decreased the work function of Mg, while the impact of remaining doping elements on the work function of Mg was trivial due to the small surface dipole moment change. The adsorption of Cl destabilized the Mg atoms at surface by weakening the bonding between surface Mg atoms. We find that a stronger hybridization of d orbits of alloying elements (e.g. Zr) with the orbits of Mg can greatly increase the local electrode potential,which even overbalances the negative effect introduced by Cl adsorbates and hence improves the corrosion resistance of Mg alloys.
Magnesium (Mg)-air battery, which is an important category of metal-air batteries, has been considered as the promising energy storage in various areas as a primary battery. However, low utilization ...efficiency due to the serious hydrogen evolution of the Mg anode impairs its discharge performance. Herein, we successfully achieve a high-energy-capacity Mg-air battery that reaches record-breaking 2134 ± 88 mAh g−1 and 2279 ± 55 mAh g−1 with magnetron-sputtered Mg50Al50 and Mg30Al70 anodes in a traditional NaCl electrolyte. The superior high capacity of this new battery can be attributed to the suppression of hydrogen evolution without inhibiting the discharge process of the anode.
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•Mg50Al50 and Mg30Al70 alloy anodes were magnetron-sputtered for a Mg-air battery.•The primary batteries with the anodes had record-breaking high specific capacity.•The passive films of the anodes effectively inhibited anodic hydrogen evolution.•The supersaturated Al in the anodes improved the capacity and reduced the activity.
The refined theory and the decomposed theorem of plates are converted into the refined theory and decomposed theorem of the axisymmetric circular cylinder. The refined theory provides the solutions ...of the axisymmetric circular cylinder without ad hoc assumptions. Expressions are obtained for all the displacements and stress components in terms of the axis displacement, and its derivatives by using Bessel’s Function and axisymmetric general solutions. On the basis of the refined theory developed in the present paper, solutions are obtained for a circular cylinder with homogeneous and non-homogenous boundary conditions, respectively. For the circular cylinder with homogeneous boundary conditions, the refined theory provides exact solutions that satisfy all of the governing equations. The exact solutions can be decomposed into two parts: the 2-orders equation and the transcendental equation. In the case of non-homogenous boundary conditions, the approximate governing equations are accurate up to the 2-order terms with respect to the radius of the circular cylinder.
Graphitic carbon nitride (g-C
N
) fundamental photophysical processes exhibit a high frequency of charge trapping due to physicochemical defects. In this study, a copper phosphide (Cu
P) and g-C
N
...hybrid was synthesized via a facile phosphorization method. Cu
P, as an electron acceptor, efficiently captures the photogenerated electrons and drastically improved the charge separation rate to cause a significantly enhanced photocatalytic performance. Moreover, the robust and intimate chemical interactions between Cu
P and g-C
N
offers a rectified charge-transfer channel that can lead to a higher H
evolution rate (HRE, 277.2 μmol h
g
) for this hybrid that is up to 370 times greater than that achieved from using bare g-C
N
(HRE, 0.75 μmol h
g
) with a quantum efficiency of 3.74% under visible light irradiation (λ = 420 nm). To better determine the photophysical characteristics of the Cu
P-induced charge antitrapping behavior, ultrafast time-resolved spectroscopy measurements were used to investigate the charge carriers' dynamics from femtosecond to nanosecond time domains. The experimental results clearly revealed that Cu
P can effectively enhance charge transfer and suppress photoelectron-hole recombination.
In this work, we investigate the problem of multisatellite resource allocation for expected long-term performance optimization with a dynamic task network model, where communication tasks generated ...by task satellites are expected to be transmitted by resource satellites in the application layer, and the set of tasks changes with satellite orbital motions. The features of the tasks include priority, execution duration, visible time, etc. Since the feature information has a high dimension and changes with time, the scheduling problem is formulated as a dynamic combinatorial optimization problem and a receding-horizon task scheduling algorithm based on the event-triggered deep reinforcement learning is proposed. A residual-fully connected network is designed to extract the features of the complex task network model, and a deep double Q-learning iteration with the experience replay memory mechanism is employed to change the allocation strategy by evaluated rewards adaptively. An event-triggered strategy is then proposed to handle urgent tasks online. Numerical simulations show the performance improvement of the proposed algorithm. For the scenario of 50 task satellites and ten resource satellites, the proposed algorithm achieves 4.1%, 5.9%, and 11.4% higher reward scores than the static deep reinforcement learning algorithm, the data-driven parallel scheduling algorithm, and the improved genetic algorithm, respectively. The computation time of the proposed algorithm is only 34.7% and 21.3% of that of the latter two algorithms, and is similar to that of the static deep reinforcement learning algorithm.
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•N,S-CS/CN achieved the high H2O2 activity in acid, neutral and alkaline conditions.•The carbon-based heterostructures could effectively avoid the charge recombination.•The ...synergistic effect of S- and N-site was conducive to H2O2 production.
Photoelectrocatalytic (PEC) H2O2 synthesis from water and oxygen is a prospective approach for the manufacture of solar fuels and value-added versatile chemicals. However, the development of the efficient photocathode remains a formidable challenge because of the inferior selectivity and yield of H2O2 derived from the multiple electron transfers affected by pH conditions. Herein, we report a metal-free carbon-based heterostructure material with N, S co-doping, where binary heteroatom-doped carbon sphere (N,S-CS) is loaded on carbon nitride (C3N4) polymer, achieving an efficient synthesis of H2O2 in a wide pH range. DFT calculations and experimental results uncover that S- and N-site can suppress the O-O cleavage and facilitate the *OOH formation through their subtle microenvironment, mediating the superior 2e- oxygen reduction selectivity to H2O2 in acids and alkalis, respectively. This work provides a cost-effective strategy for designing an efficient photocathode for H2O2 production in a wide pH environment.
The serious safety issues caused by uncontrollable lithium (Li) dendrite growth, especially at high current densities, seriously hamper the rapid charging of Li metal‐based batteries. Here, the ...construction of Al–Li alloy/LiCl‐based Li anode (ALA/Li anode) is reported by displacement and alloying reaction between an AlCl3‐ionic liquid and a Li foil. This layer not only has high ion‐conductivity and good electron resistivity but also much improved mechanical strength (776 MPa) as well as good flexibility compared to a common solid electrolyte interphase layer (585 MPa). The high mechanical strength of the Al–Li alloy interlayer effectively eliminates volume expansion and dendrite growth in Li metal batteries, so that the ALA/Li anode achieves superior cycling for 1600 h (2.0 mA cm−2) and 1000 cycles at an ultrahigh current density (20 mA cm−2) without dendrite formation in symmetric batteries. In lithium–sulfur batteries, the dense alloy layer prevents direct contact between polysulfides and Li metal, inhibiting the shuttle effect and electrolyte decomposition. Long cycling performance is achieved even at a high current density (4 C) and a low electrolyte/sulfur (6.0 µL mg−1). This easy fabrication process provides a strategy to realize reliable safety during the rapid charging of Li‐metal batteries.
The universal Al–Li alloy‐based layer is demonstrated to be highly effective for stabilizing the lithium metal anode at an ultrahigh current density. The high strength layer not only inhibits the growth of lithium dendrites but also prevents the parasitic reactions of Li with the liquid electrolyte and polysulfides.
The difference effect and hydrogen evolution behavior of pure Mg in alkaline NH
4
+
containing solutions are systematically investigated. The Mg electrode exhibits a positive difference effect, ...rather the traditional negative difference effect, with the anomalous hydrogen evolution in the alkaline 0.1 M (NH
4
)
2
SO
4
, 0.1 M NH
4
HCO
3
and 0.05 M (NH
4
)
2
CO
3
solutions. This is primarily attributed to the corrosion product film dissolution effect of NH
4
+
and the formation of the black corrosion products. The hydrogen evolution kinetics with the difference effects are deduced and explained by the prevailing incomplete film Mg
+
mechanism and enhanced catalytic activity mechanism.
Graphical abstract
The freestanding MXene films are promising for compact energy storage ascribing to their high pseudocapacitance and density, yet the sluggish ion transport caused by the most densely packed structure ...severely hinders their rate capability. Here, a reassembly strategy for constructing freestanding and flexible MXene‐based film electrodes with a tunable porous structure is proposed, where the Ti3C2Tx microgels disassembled from 3D structured hydrogel are reassembled together with individual Ti3C2Tx nanosheets in different mass ratios to form a densely packed 3D network in microscale and a film morphology in macroscale. The space utilization of produced film can be maximized by a good balance of the density and porosity, resulting in a high volumetric capacitance of 736 F cm−3 at an ultrahigh scan rate of 2000 mV s−1. The fabricated supercapacitor yields a superior energy density of 40 Wh L−1 at a power density of 0.83 kW L−1, and an energy density of 21 Wh L−1 can be still maintained even when the power density reaches 41.5 kW L−1, which are the highest values reported to date for symmetric supercapacitors in aqueous electrolytes. More promisingly, the reassembled films can be used as electrodes of flexible supercapacitors, showing excellent flexibility and integrability.
A reassembly strategy for producing a flexible MXene‐based electrode with tunable porosity is proposed, in which the volumetric capacitance under ultrahigh rate is maximized by balancing the density and porosity. The assembled symmetric device delivers the highest energy density of 40 Wh L−1 and the highest power density of 41.5 kW L−1.
The purposes of this research were to study the restoration on the cognitive ability of rat models with vascular dementia (VaD) by repetitive transcranial magnetic stimulation (rTMS) treatment and ...its impacts on synaptic plasticity in hippocampal CA1 area and to further explore the molecular mechanisms of the rTMS treatment on vascular dementia. Thirty-six male Wistar rats were randomly divided into four groups: the normal control group, the vascular dementia model group, the low-frequency rTMS group, and the high-frequency rTMS group. Two-vessel occlusion was employed to make VaD models. Low-frequency rTMS group rats were treated with 0.5 Hz rTMS for 6 weeks. High-frequency rTMS group rats underwent 5 Hz rTMS for 6 weeks. Morris water maze was carried out to detect the ability of spatial learning and memory of rats. The ultra-structural changes of synapses in four groups were observed by transmission electron microscope. Then the expressions of brain-derived neurotrophic factor (BDNF), NMDAR1, and Synaptophysin (SYN) mRNA and proteins in hippocampal CA1 area were determined by real-time PCR, western blot, and immunohistochemistry assay. After rTMS treatment, the learning and memory abilities of VaD rats improved significantly. The ultra-structures of synapses in hippocampal CA1 area in rTMS groups were reformed. The mRNA and protein expressions of BDNF, NMDAR1, and SYN in the low-frequency rTMS group and in the high-frequency rTMS group were higher than that in VaD model group (
P
< 0.05). rTMS plays an important and beneficial role in the restoration treatment of vascular dementia, which may be related to the mechanism that rTMS can increase the mRNA and protein expressions of BDNF, NMDAR1, and SYN and affect the synaptic plasticity in hippocampal CA1 area.
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