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.

Encapsulation of Titanium Disulfide into MOF-Derived N,S-Doped Carbon Nanotablets Toward Suppressed Shuttle Effect and Enhanced Sodium Storage Performance.

Titanium disulfide (TiS2) is a promising anode material for sodium-ion batteries due to its high theoretical capacity, but it suffers from severe volume variation and shuttle effect of the intermediate polysulfides. To overcome the drawbacks, herein the successful fabrication of TiS2@N,S-codoped C (denoted as TiS2@NSC) through a chemical vapor reaction between Ti-based metal-organic framework (NH2-MIL-125) and carbon disulfide (CS2) is demonstrated. The C─N bonds enhance the electronic/ionic conductivity of the TiS2@NSC electrode, while the C─S bonds provide extra sodium storage capacity, and both polar bonds synergistically suppress the shuttle effect of polysulfides. Consequently, the TiS2@NSC electrode demonstrates outstanding cycling stability and rate performance, delivering reversible capacities of 418/392 mAh g-1 after 1000 cycles at 2/5 A g-1. Ex situ X-ray photoelectron spectroscopy and transmission electron microscope analyses reveal that TiS2 undergoes an intercalation-conversion ion storage mechanism with the generation of metallic Ti in a deeper sodiation state, and the pristine hexagonal TiS2 is electrochemically transformed into cubic rock-salt TiS2 as a reversible phase with enhanced reaction kinetics upon sodiation/desodiation cycling. The strategy to encapsulate TiS2 in N,S-codoped porous carbon matrices efficiently realizes superior conductivity and physical/chemical confinement of the soluble polysulfides, which can be generally applied for the rational design of advanced electrodes.

In Situ Observation of Field-Induced Nanoprotrusion Growth on a Carbon-Coated Tungsten Nanotip.

Nanoprotrusion (NP) on metal surface and its inevitable contamination layer under high electric field is often considered as the primary precursor that leads to vacuum breakdown, which plays an extremely detrimental effect for high energy physics equipment and many other devices. Yet, the NP growth has never been experimentally observed. Here, we conduct field emission (FE) measurements along with in situ transmission electron microscopy (TEM) imaging of an amorphous-carbon (a-C) coated tungsten nanotip at various nanoscale vacuum gap distances. We find that under certain conditions, the FE current-voltage (I-V) curves switch abruptly into an enhanced-current state, implying the growth of an NP. We then run field emission simulations, demonstrating that the temporary enhanced-current I-V is perfectly consistent with the hypothesis that a NP has grown at the apex of the tip. This hypothesis is also confirmed by the repeatable in situ observation of such a nanoprotrusion and its continued growth during successive FE measurements in TEM. We tentatively attribute this phenomenon to field-induced biased diffusion of surface a-C atoms, after performing a finite element analysis that excludes the alternative possibility of field-induced plastic deformation.

Contribution of oxygen vacancies to phase transition and ferroelectricity of Al:HfO2films.

We investigate the effects of oxygen vacancies on the ferroelectric behavior of Al:HfO2films annealed in O2and N2atmosphere. X-ray photoelectron spectroscopy results showed that the O/Hf atomic ratio was 1.88 for N2-annealed samples and 1.96 for O2-annealed samples, implying a neutralization of oxygen vacancies during O2atmosphere annealing. The O2-annealed films exhibited an increasing remanent polarization from 23µC cm-2to 28µC cm-2after 104cycles, with a negligible leakage current density of ∼2µA cm-2, while the remanent polarization decreased from 29µC cm-2to 20µC cm-2after cycling in the N2-annealed films, with its severe leakage current density decreasing from ∼1200µA cm-2to ∼300µA cm-2.A phase transition from the metastable tetragonal (t) phase to the low-temperature stable orthorhombic (o) phase and monoclinic (m) phase was observed during annealing. As a result of the fierce· competition between the t-to-o transition and the t-to-m transition, clear grain boundaries of several ruleless atomic layers were formed in the N2-annealed samples. On the other hand, the transition from the t-phase to the low-temperature stable phase was found to be hindered by the neutralization of oxygen vacancies, with almost continuous grain boundaries observed. The results elucidate the phase transformation caused by oxygen vacancies in the Al:HfO2films, which may be helpful for the preparation of HfO2-based films with excellent ferroelectricity.

Improved ion adsorption capacities and diffusion dynamics in surface anchored MoS2⊥Mo4/3B2 and MoS2⊥Mo4/3B2O2 heterostructures as anodes for alkaline metal-ion batteries.

First-principles calculations were performed to analyze the atomic structures and electrochemical energy storage properties of novel MoS2⊥boridene heterostructures by anchoring MoS2 nanoflakes on Mo4/3B2 and Mo4/3B2O2 monolayers. Both thermodynamic and thermal stabilities of each heterostructure were thoroughly evaluated from the obtained binding energies and through first-principles molecular dynamics simulations at room temperature, confirming the high formability of the heterostructures. The electrochemical properties of MoS2⊥Mo4/3B2 and MoS2⊥Mo4/3B2O2 heterostructures were investigated for their potential use as anodes for alkaline metal ion batteries (Li+, Na+ and K+). It was revealed that Li+ and Na+ can form multiple stable full adsorption layers on both heterostructures, while K+ forms only a single full adsorption layer. The presence of a negative electron cloud (NEC) contributes to the stabilization of a multi-layer adsorption mechanism. For all investigated alkaline metal ions, the predicted ion diffusion dynamics are relatively sluggish for the adsorbates in the first full adsorption layer on MoS2⊥boridene heterostructures due the relatively large migration energies (>0.50 eV), compared to those of second or third full adsorption layers (<0.30 eV). MoS2⊥Mo4/3B2O2 exhibited higher onset and mean open circuit voltages as anodes for alkaline metal-ion batteries than MoS2⊥Mo4/3B2 hybrids because of enhanced interactions between the adsorbate and the Mo4/3B2O2 monolayer with the presence of O-terminations. Tailoring the size and horizontal spacing between two neighboring MoS2 nano-flakes in heterostructures led to high theoretical capacities for LIBs (531 mA h g-1), SIBs (300 mA h g-1) and PIBs (131 mA h g-1) in the current study.

A Review of Phosphorus Structures as CO2 Reduction Photocatalysts.

Effective photocatalytic carbon dioxide (CO2 ) reduction into high-value-added chemicals is promising to mitigate current energy crisis and global warming issues. Finding effective photocatalysts is crucial for photocatalytic CO2 reduction. Currently, metal-based semiconductors for photocatalytic CO2 reduction have been well reviewed, while review of nonmetal-based semiconductors is almost limited to carbon nitrides. Phosphorus is a promising nonmetal photocatalysts with various allotropes and tunable band gaps, which has been demonstrated to be promising non-metallic photocatalysts. However, no systematic review about phosphorus structures for photocatalytic CO2 reduction reactions has been reported. Herein, the progresses of phosphorus structures as photocatalysts for CO2 reduction are reviewed. The fundamentals of photocatalytic CO2 reduction, corresponding properties of phosphorus allotropes, photocatalysts with phosphorus doping or phosphorus-containing ligands, research progress of phosphorus allotropes as photocatalysts for CO2 reduction have been reviewed in this paper. The future research and perspective of phosphorus structures for photocatalytic CO2 reduction are also presented.

Introducing Hybrid Defects of Silicon Doping and Oxygen Vacancies into MOF-Derived TiO2-X @Carbon Nanotablets Toward High-Performance Sodium-Ion Storage.

Titanium dioxide (TiO2 ) is a promising anode material for sodium-ion batteries (SIBs), which suffer from the intrinsic sluggish ion transferability and poor conductivity. To overcome these drawbacks, a facile strategy is developed to synergistically engineer the lattice defects (i.e., heteroatom doping and oxygen vacancy generation) and the fine microstructure (i.e., carbon hybridization and porous structure) of TiO2 -based anode, which efficiently enhances the sodium storage performance. Herein, it is successfully realized that the Si-doping into the MIL-125 metal-organic framework structure, which can be easily converted to SiO2 /TiO2-x @C nanotablets by annealing under inert atmosphere. After NaOH etching SiO2 /TiO2-x @C which contains unbonded SiO2 and chemically bonded SiOTi, thus the lattice Si-doped TiO2-x @C (Si-TiO2-x @C) nanotablets with rich Ti3+ /oxygen vacancies and abundant inner pores are developed. When examined as an anode for SIB, the Si-TiO2-x @C exhibits a high sodium storage capacity (285 mAh g-1 at 0.2 A g-1 ), excellent long-term cycling, and high-rate performances (190 mAh g-1 at 2 A g-1 after 2500 cycles with 95.1% capacity retention). Theoretical calculations indicate that the rich Ti3+ /oxygen vacancies and Si-doping synergistically contribute to a narrowed bandgap and lower sodiation barrier, which thus lead to fast electron/ion transfer coefficients and the predominant pseudocapacitive sodium storage behavior.

Violet Antimony Phosphorus with Enhanced Photocatalytic Hydrogen Evolution.

Violet phosphorus (VP), a recently confirmed layered elemental structure, is demonstrated to have unique photoelectric, mechanical, and photocatalytic properties. Element substitution plays a significant role in modifying the physical/chemical properties of semiconducting materials. Herein, antimony is adopted to substitute some phosphorus atoms in VP crystals to tune their physical and chemical properties, resulting in a significantly enhanced photocatalytic hydrogen evolution performance. The antimony-substituted violet phosphorus single crystal (VP-Sb) is synthesized and characterized by single crystal X-ray diffraction (CSD-2214937). The bandgap of VP-Sb has been found to be lowered from that of VP by UV/vis diffuse reflectance spectroscopy and density-functional theory (DFT) calculation, enhancing the optical absorption during photocatalytic reaction. The conducting band minimum of VP-Sb is found to be upshifted from that of VP from measurements and calculation, enhancing its hydrogen reduction activity. The valance band maximum is found to be lowered to weaken its oxidation activity. The edge of VP-Sb is calculated to have an excellent H* adsorption-desorption performance and superior H2 generation kinetics. The H2 evolution rate of VP-Sb is demonstrated to be significantly enhanced to be 1473 µmol h-1 g-1 , about five times of that of pristine VP (299 µmol h-1 g-1 ) under the same experimental conditions.

Improving the High-Temperature Energy Storage Performance of Epoxy Films: Moderately Reducing Unsaturation for Extremely High Efficiency.

The rapid development of renewable energy systems, electric vehicles, and pulsed equipment requires energy storage media to have a high energy storage density and efficiency in a wide temperature range. The state-of-the-art biaxially oriented polypropylene (BOPP) film is insufficient to meet the growing demand for energy storage devices due to its low energy storage density and working temperature, which make it a research hotspot for developing dielectric energy storage materials. In this manuscript, based on the epoxy materials that have been shown as a potential energy storage medium, we aim to reduce the influence of the benzene ring delocalization structure on the energy storage losses and enhance the efficiency by gradually replacing them with cyclohexane structures to adjust the segment unsaturation of epoxy materials. The results show that by partially reducing the unsaturation of the curing agent, the epoxy material achieves an excellent high-temperature energy storage density of 2.21 J/cm3 at 150 °C and 300 MV/m while maintaining an extremely high energy storage efficiency of 99.2%. Leakage current density and high-voltage dielectric spectroscopy tests confirm that a moderate reduction of the segment unsaturation of epoxy materials can greatly inhibit polarization loss at high temperatures, which may explain their high energy storage efficiency.

A Study on the Clinical Significance of Blood Exosomal PD-L1 in Non-Small Cell Lung Cancer Patients and its Correlation with PD-L1 in Tumor Tissues.

Exosomal programmed cell-death ligand 1 (ePD-L1) can influence immune inhibition and dysfunction. We were dedicated to unearthing the relation between ePD-L1 in blood and pathological characteristics as well as PD-L1 in tumor tissues. We recruited 65 non-small cell lung cancer (NSCLC) patients for exosome extraction and detected the blood ePD-L1 expression in these patients by enzyme-linked immunosorbent assay (ELISA) method. Besides, the correlation between blood ePD-L1 and patients' pathological characteristics was also analyzed. The expression of PD-L1 in tumor tissues was tested by immunohistochemistry (IHC) and its correlation with blood ePD-L1 expression level was analyzed by Spearman correlation coefficient. No significant correlation was observed in PD-L1 expression levels between blood-derived exosome and tumor tissue. Altogether, high blood ePD-L1 expression was relevant to NSCLC progression, while no such relevance to PD-L1 expression in tumor tissue.

Single injection technique with ultrasound-guided superficial cervical fascia block combined with brachial plexus block in clavicular surgery: a prospective randomized comparative trial.

BACKGROUND: To investigate the effects of a single injection technique with ultrasound-guided superficial cervical fascia block combined with brachial plexus block in clavicular surgery. METHODS: Forty patients, 25 males and 15 females, aged 18-85 years with ASA class I or II underwent unilateral clavicular fracture internal fixation. The patients were randomly divided into a superficial cervical plexus block group (group S, n = 20) and a superficial cervical fascia block group (group F, n = 20). First, the brachial plexus of the intermuscular sulcus of all patients was blocked with an ultrasound-guided injection of one injection with 15ml 0.33% ropivacaine 15ml in both groups. Second, the superficial cervical plexus was blocked by another injection of 5-8ml 0.33% ropivacaine in group S, and the superficial cervical fascia was blocked by an injection with 5-8ml 0.33% ropivacaine in Group F. We evaluated operation time, onset time of anaesthesia, effective time and the grades of nerve block effect in the two groups. Additionally, we evaluated the incidences of local anaesthetic poisoning, hoarseness, dyspnoea, and postoperative nausea and vomiting, and the number of patients requiring remedial analgesia within 24 h. Repeated measurements were analysed by repeated data analysis of variance, and count data were compared by the χ2 test. A P value < 0.05 was considered statistically significant. RESULTS: The operation time and onset time in Group F were significantly shorter than those in group S (P < 0.05); the effect of intraoperative block was better than that in group S (P < 0.05), and the effective time was significantly longer in group F than in group S (P < 0.05). However, no severe case of dyspnoea, local anaesthetic poisoning or hoarseness after anaesthesia occurred in either of two groups. There was no significant difference in the rate of postoperative salvage analgesia or that of postoperative nausea and vomiting between the two groups. CONCLUSIONS: The application of the single injection technique with ultrasound-guided superficial cervical fascia block combined with brachial plexus block in clavicular surgery is beneficial because it shortens the operation time, has a faster onset, produces a more effective block and prolongs the longer analgesia time. TRIAL REGISTRATION: Chinese Clinical Trial Registry- ChiCTR2200064642(13/10/2022).

Excellent Vacuum Pulsed Flashover Characteristics Achieved in Dielectric Insulators Functionalized by Electronegative Halogen-Phenyl and Naphthyl Groups.

Designing electrical insulation materials with excellent surface flashover strength in a vacuum environment is crucial for high-power equipment and aerospace devices. In the present paper, the effect of two types of electronegative groups, the halogen-phenyl groups and the aromatic π-conjugated naphthyl groups, is used to greatly improve the vacuum flashover characteristics of polystyrene (PS), a commonly used polymer dielectric material in high-power devices. By polymerization of the monomers containing these electronegative groups, the bulk insulation material as a whole is modified expediently. In comparison to the base polymer PS, the electron affinity of the structures containing strong electronegative groups is studied with first-principles calculations based on the density functional theory. The nanosecond pulsed vacuum flashover testing results show that the vacuum flashover strength is increased by 10% after replacing the PS pendant phenyl groups with fluorophenyl groups and increased by 44% when replaced with the naphthyl groups. Furthermore, the thermally stimulated current and secondary electron emission yield spectroscopies are measured, to study the influence of strong electronegative groups on the trapping characteristics and further the electron-emitting features of the polymer dielectrics, which are closely related to the charged particle multiplication process during the vacuum flashover. The results prove that introducing strong electronegative groups can inhibit the triggering of vacuum flashover, suppress the electron emission, delay the flashover process, and thus greatly increase the vacuum flashover voltage. The study of this paper not only puts forward two groups of easily processable polymers with excellent vacuum flashover strength but also paves ways for the future material design of special insulation polymers.

Aqueous Proton Transportation in Graphene-Based Nanochannels.

Graphene oxide (GO) has been unveiled to exhibit high proton conductivity in a humidified or aqueous environment, making it a promising candidate to construct proton conduction nanochannels. In this work, we systematically investigate how the confinement effect and surface chemistry influence the proton transportation behavior in graphene-based nanochannels via extensive ReaxFF MD simulations. Graphene (GE), graphane (GA), and hydroxygraphane (HG) sheets were employed to mimic the graphitic and functionalized region of GO and construct nanochannels with different interlayer distances. We find that confined water molecules are stratified and their orientation is influenced by the surface chemistry, thus impacting the distribution of protons. Surface chemistry makes the compression of the hydrogen-bond network induced by the confinement effect more variable. The hydrogen-bond network between GE slabs is crushed by extreme confinement and ultrafast proton transportation behavior mainly achieved via vehicle mechanism. Meanwhile, the hydrogen-bond network and solvation structure can be kept more complete with the existence of functional groups. The hydrogen bonds formed with surface functional groups impede the transportation of water molecules but allow more Grotthuss hopping of protons to different extents. Our work clarified the proton transportation mechanism in graphene-based nanochannels with different interlayer distances and surface chemistry and can guide the future design of proton conduction devices such as proton exchange membranes.

Preparation of Montmorillonite Nanosheets with a High Aspect Ratio through Heating/Rehydrating and Gas-Pushing Exfoliation.

Montmorillonite (MMT) is an abundant silicate mineral with ultrahigh stability. The exfoliation of stacked MMT into high-aspect-ratio nanosheets is of crucial importance for various applications such as toxic gas suppression, barrier property enhancement, flame retardancy, and ion conduction. In this work, we develop a new heating/rehydrating and gas-pushing method that can successfully exfoliate MMT into nanosheets with aspect ratios (600-5000) far higher than the currently reported values (1-120). The MMT first goes through a "starvation pretreatment" under different heating temperatures to improve its hydrophilicity and is then rehydrated in a hydrogen peroxide solution. The hydrogen peroxide in the MMT interlayer space can decompose into water and oxygen bubbles, thus finally leading to the exfoliation via gas-pushing while preserving the large lateral size (mainly in the range of 1-6 µm) of the nanosheets. By changing the pretreatment temperature and pH value of the hydrogen peroxide solution, the exfoliation performance can be tuned. This simple and low-cost exfoliation method is promising to achieve the mass production of MMT nanosheets with a high aspect ratio and may promote its application in various fields such as energy conversion, drug delivery, and photocatalysis.

On the Origins of Stereo- and Regio-Selectivities in the Formation of Fullerene-Fluorene Dyads.

Recently, a novel [2+2] cycloaddition between the classical Ih-C60 and a fluorenylideneallene complex has been achieved experimentally. In the fullerene-fluorene dyad product, stereo- and regio-selectivities were found in the experiment, but the reasons are still unknown. Our theoretical studies suggest that, based on a diradical pathway, the structural selectivity of the product strongly depends on the structural/electronic features of the fluorenylideneallene and C60 complexes. When the R1 group in fluorenylideneallene denotes the H atom, the E-type product is more stable than the Z-type one, whereas other bulkier R1 groups lead to the reverse due to their steric hindrance. The π orbital conjugation between the fluorenyl group and the Cß═Cγ bond in fluorenylideneallene is the main reason for the high selectivity of ß,γ-cycloaddition. Analyses of both frontier orbitals and spin density for the intermediate structure suggest a diradical pathway of the reaction between fluorenylideneallene and C60 and uncover a decisive role of the LUMO of C60 toward regio-selectivity, which conduces to a high selectivity of the (6,6)-addition product.

Attenuation investigation influenced by the temperature and strain in an optical fiber composite low voltage cable.

Optical fiber composite low voltage cable (OPLC) is an optimal way of connecting the smart grid with the load. In this paper, the field distribution of temperature and stress is simulated by applying the finite element method. At the overload condition, the fiber unit's temperature rises to 59°C that generates the strain of 387 µÎµ. This strain and temperature together result in the additional attenuation of 0.053 dB/km in the optical fiber. Temperature and strain are termed as the major contributing factors towards the attenuation in the optical fiber as temperature caused 16.03% while strain caused 80.56% of the total loss.

Enhancing the Surface Flashover Strength of Polystyrene in Vacuum by Secondary Electron Emission Suppression through Cross-Linking.

Insulation materials with excellent dielectrics-vacuum interface breakdown strength are irreplaceable in equipment such as particle accelerators, fusion ignition, and related aerospace devices. In this article, the segment structure of a typical insulation polymer, polystyrene, has been modified by introducing divinylbenzene to form cross-linking junctures and adjust the cross-linking density. The influence of cross-linking on its electron absorb-emit feature and further on the vacuum pulsed flashover characteristics has been systematically studied. A series of broadband dielectric spectroscopy (BDS) and thermally stimulated current (TSC) experiments indicate that this cross-linking network inhibits the movement of the polar segments, leading to a drastic change in the charge-trapping behavior of dielectric surface layer materials. The trapping charge density is increased, and the trapping energy is transferred to deeper-level regions. These lead to the observed suppression of secondary electron emission (SEE) of highly cross-linked polystyrenes exposed in vacuum. And, quite sensibly, the nanosecond pulsed vacuum flashover tests show that the polystyrenes with higher cross-linking density have enhanced flashover strength. Moreover, to further investigate the relationship between the dielectric SEE behavior and its vacuum flashover process, a 2-D model is established and analyzed on the basis of the particle in the cell with the Monte Carlo collision (PIC-MCC) method.

How Can the η1-Type Fullerene-Metal Bond Survive? A Systematic Survey of Reactions between Mono-EMFs and (M'Ln)2 Dimers.

Recently, one η1-coordinated complex of endohedral metallofullerene (EMF) Y@C2v(9)-C82[Re(CO)5] has been synthesized and characterized with a highly efficient radical-coupling methodology by performing a photochemical reaction between Y@C2v(9)-C82 and [Re(CO)5]2 complexes. Theoretical investigations with the density functional theory reveal that this complex is stabilized by an ionic C-Re bond. The reactions of M@C2v(9)-C82 (M = Sc, Y, La) with [Re(CO)5]2 suggest that the reaction energies differ little because of similar single occupied molecular orbitals (SOMOs) of M@C2v(9)-C82. In the reactions of Y@C2v(9)-C82 with various transition-metal complexes [M'Ln]2 (M' = Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir), the C-M' bonds with Mn, Tc, Re, Fe, Ru, and Os can stably exist, whereas those with Co, Rh, and Ir are unstable. Further analyses disclose that, in each element group, the stability of the C-M' bond is mainly determined by the bond energy of the M'-M' bond, which is related to the dσ orbital of the M'Ln species. Moreover, the very-low-energy dσ orbitals and large geometrical distortions of M'(CO)4 (M' = Co, Rh, Ir) lead to poor stabilities of the C-M' (M' = Co, Rh, Ir) bonds. As comparison, the reactions of Y@Cs(6)-C82 and La@C72 have been investigated. The Y@Cs(6)-C82 structure is more reactive toward the [M'Ln]2 complexes than Y@C2v(9)-C82 thanks to a lower SOMO of Y@Cs(6)-C82 than that of Y@C2v(9)-C82, which derives from position change of the Y atom in Cs(6)-C82 during the reactions. However, the formation of [Y@Cs(6)-C82]2 suppresses the formation of several C-M' bonds. The reactivity of La@C72 is weak due to a high LUMO+1 of C72, which leads to a high SOMO of La@C72. We believe that this theoretical study provides primary principles of radical-coupling reactions of EMFs and will be valuable for future research of organometallic complexes of fullerene.

A synergistic interplay between dopant ALD cycles and film thickness on the improvement of the ferroelectricity of uncapped Al:HfO2nanofilms.

The Al:HfO2ferroelectric nanofilms with different total thicknesses and distributions of Al-rich strips are prepared using atomic layer deposition (ALD) in an uncapped configuration. The synergistic interplay between the number of Al-rich layers and the thickness of total film offers the additional flexibility to boost the ferroelectricity of the resulting Al:HfO2nanofilms. By carefully optimizing both the ALD cycles for dopant layer and the total film thickness in the preparation, the HfO2nanofilms in post-deposition annealing can exhibit excellent ferroelectricity. The highest remanent polarization (2Pr) of 51.8µC cm-2is obtained in a 19.4 nm thick Al:HfO2nanofilm at the dopant concentration of 11.1 mol% with a three ALD cycles for Al-rich strips. Remarkable remanent polarization value observed in the uncapped electrode clamping film paves a new way to explore the origin of ferroelectricity in hafnium oxide nanofilms. The observed ferroelectricity of the nanofilm is affected neither by the presence of an interface between the upper electrode and the film nor the choices of the materials of upper electrode in the measurement, ensuring a high flexibility in the designing and fabrication of the relevant devices in the future.

Synergizing Phase and Cavity in CoMoOx Sy Yolk-Shell Anodes to Co-Enhance Capacity and Rate Capability in Sodium Storage.

Sodium-ion batteries (SIBs) have been recognized as the promising alternatives to lithium-ion batteries for large-scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization-free Na+ insertion/extraction. Herein, a facile co-engineering on polymorph phases and cavity structures is developed based on CoMo-glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoOx Sy with synergized partially sulfidized amorphous phase and yolk-shell confined cavity. When developed as anodes for SIBs, such CoMoOx Sy electrodes deliver a high reversible capacity of 479.4 mA h g-1 at 200 mA g-1 after 100 cycles and a high rate capacity of 435.2 mA h g-1 even at 2000 mA g-1 , demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation-induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk-shell cavity. Such yolk-shell nano-battery materials are merited with co-tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future.