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In Ni(OH)2, a greater extent of band (3d electron states with eg symmetry) broadening can facilitate electron transfer from the electrocatalyst to the external circuit, leading to higher OER catalytic performance.

The superplasticity of Ti-43Al-9V-0.2Y alloy sheet hot-rolled at 1100 °C was systematically investigated in the temperature range of 750−900 °C under an initial strain rate of 10−4 s−1. A bimodal γ grain-distribution microstructure of TiAl alloy sheet, with abundant nano-scale or sub-micron γ laths embedded inside β matrix, exhibits an impressive superplastic behaviour. This inhomogeneous microstructure shows low-temperature superplasticity with a strain-rate sensitivity exponent of m = 0.27 at 800 °C, which is the lowest temperature of superplastic deformation for TiAl alloys attained so far. The maximum elongation reaches ~360% at 900 °C with an initial strain rate of 2.0 × 10−4 s−1. To elucidate the softening mechanism of the disordered β phase during superplastic deformation, the changes of phase composition were investigated up to 1000 °C using in situ high-temperature X-ray diffraction (XRD) in this study. The results indicate that β phase does not undergo the transformation from an ordered L20 structure to a disordered A2 structure and cannot coordinate superplastic deformation as a lubricant. Based on the microstructural evolution and occurrence of both γ and β dynamic recrystallization (DR) after tensile tests as characterized with electron backscatter diffraction (EBSD), the superplastic deformation mechanism can be explained by the combination of DR and grain boundary slipping (GBS). In the early stage of superplastic deformation, DR is an important coordination mechanism as associated with the reduced cavitation and dislocation density with increasing tensile temperature. Sufficient DR can relieve stress concentration arising from dislocation piling-up at grain boundaries through the fragmentation from the original coarse structures into the fine equiaxed ones due to recrystallization, which further effectively suppresses apparent grain growth during superplastic deformation. At the late stage of superplastic deformation, these equiaxed grains make GBS prevalent, which can effectively avoid intergranular cracking and is conducive to the further improvement in elongation. This study advances the understanding of the superplastic deformation mechanism of intermetallic TiAl alloy.

Developing affordable and efficient electrocatalysts as precious metal alternatives toward the hydrogen evolution reaction (HER) is crucially essential for the substantial progress of sustainable H2 energy-related technologies. The dual manipulation of coordination chemistry and geometric configuration for single-atom catalysts (SACs) has emerged as a powerful strategy to surmount the thermodynamic and kinetic dilemmas for high-efficiency electrocatalysis. We herein rationally designed N-doped multichannel carbon nanofibers supporting atomically dispersed Mo sites coordinated with C, N, and O triple components (labeled as Mo@NMCNFs hereafter) as a superior HER electrocatalyst. Systematic characterizations revealed that the local coordination microenvironment of Mo is determined to be a Mo-O1N1C2 moiety, which was theoretically probed to be the energetically favorable configuration for H intermediate adsorption by density functional theory calculations. Structurally, the multichannel porous carbon nanofibers with open ends could effectively enlarge the exposure of active sites, facilitate mass diffusion/charge transfer, and accelerate H2 release, leading to promoted reaction kinetics. Consequently, the optimized Mo@NMCNFs exhibited superior Pt-like HER performance in 0.5 M H2SO4 electrolyte with an overpotential of 66 mV at 10 mA cm-2, a Tafel slope of 48.9 mV dec-1, and excellent stability, outperforming a vast majority of the previously reported nonprecious HER electrocatalysts. The concept of both geometric and electronic engineering of SACs in this work may provide guidance for the design of high-efficiency molecule-like heterogeneous catalysts for a myriad of energy technologies.

Aqueous zinc-ion batteries (ZIBs) have attracted considerable attention because of their low cost, high intrinsic safety, and high volumetric capacity. However, unexpected dendrite growth and side reactions that arise at the Zn anode can severely hinder the mass adoption of ZIBs in practical applications. Herein, we report a dendrite-free ZIB anode via the hybridization of a eutectic ZnAl alloy with a copper mesh (denoted as ZnAl@Cu-mesh). The eutectic structure of the ZnAl alloy is composed of alternating Zn blocks and Al nanoflakes. The Al nanoflakes sacrificially consume the oxygen in the electrolyte to form an Al2O3/Al shell-core structure, which in turn guides the Zn deposition process by restraining the lateral diffusion of zinc ions and hence reducing the extent of dendrite formation. This process can synergistically reduce the likelihood of Zn passivation, which allows the Zn region to remain electrochemically active for the Zn stripping/plating process. Meanwhile, a copper mesh is used as a scaffold to provide uniform electric field distribution. As a result, the symmetric ZnAl@Cu-mesh//ZnAl@Cu-mesh cell presents appreciably low polarization (30 mV at 0.5 mA cm-2) and excellent cycling stability (240 h at 0.5 mA cm-2), as compared to Zn//Zn. Based on the postmortem investigation, ZnAl@Cu-mesh is able to retain a dendrite-free morphology after cycling at 1 mA cm-2, while significant dendrite formation can be observed for Zn. More impressively, the ZnAl@Cu-mesh//V2O5 full cell is able to achieve a 95% capacity retention after 2000 cycles at 2 A g-1, whereas its counterpart assembled with Zn fails after only 750 cycles because of short-circuit. Thus, the composite alloying strategy proposed in this work may provide an appealing direction toward the future development of dendrite-free anodes for rechargeable secondary batteries.

Manganese-based oxide is arguably one of the most well-studied cathode materials for zinc-ion battery (ZIB) due to its wide oxidation states, cost-effectiveness, and matured synthesis process. As a result, there are numerous reports that show significant strides in the progress of Mn-based oxides as ZIB cathode. However, ironically, due to the sheer number of Mn-based oxides that have been published in recent years, there remain certain contemplations with regards to the electrochemical performance of each type of Mn-based oxides and their performance comparison among various Mn polymorphs and oxidation states. Thus, to provide a clearer indication of the development of Mn-based oxides, the recent progress in Mn-based oxides as ZIB cathode was summarized systematically in this Review. More specifically, (1) the classification of Mn-based oxides based on the oxidation states (i. e., MnO2 , Mn3 O4 , Mn2 O3 , and MnO), (2) their respective polymorphs (i. e., α-MnO2 and δ-MnO2 ) as ZIB cathode, (3) the modification strategies commonly employed to enhance the performance, and (4) the effects of these modification strategies on the performance enhancement were reviewed. Lastly, perspectives and outlook of Mn-based oxides as ZIB cathode were discussed at the end of this Review.

Vanadium-based oxide is widely investigated as a zinc ion battery (ZIB) cathode due to its ability to react reversibly with Zn2+. Despite its successful demonstration, modification with simple molecules has shown some promise in enhancing the performance of ZIBs. Thus, this presents an immense opportunity to explore simple molecules that can dramatically improve the electrochemical performance of electrodes. Thus, the effect of CO2 modification is studied in this work by decomposing oxalic acid within a hydrated V6O13 framework. Based on the collective results, the presence of CO2 drastically lowers the relative energy of Zn2+ diffusion through the pathways by forming weak electrostatic interactions between OCO2 and Zn2+. This leads to an enlarged diffusion contribution, which consequently results in enhanced stability and better rate performance. The as-synthesized CO2-V6O13 electrode delivers one of the highest specific capacities reported for vanadium-based oxides of ca. 471 mAh g-1. Furthermore, an excellent cyclic stability of 80% capacity retention after 4000 cycles at 2 A g-1 is recorded for CO2-V6O13, which suggests the importance of simple molecules in the material framework toward the enhancement of ZIB cathode performance.

In order to develop functional energy storage device, it is necessary to improve the energy and power density. As a potential candidate that can synergistically harmonize energy and power density, lithium ion capacitor (LIC) has shown exciting promises in recent years. However, in the recent years, alternative metal has been explored to replace lithium in such metal-ion capacitor system. Hence, in this work we present zinc ion capacitor (ZIC) in which zinc acts as negative electrode and Metal Organic framework (MOF) derived carbon as positive electrode. The assembled ZIC was able to demonstrate exceptional power density of 85.5 kW kg-1 and a maximal energy density of 36.4 W h kg-1, together with 99 % capacitance retention after cycling for 20 000 cycles.

Defects can be generated when growing diamond on heterogeneous substrates. The problem dampers the widespread use of diamond films. In this paper, a novel approach is proposed which grows diamond on graphene quasi-homogeneous epitaxial substrate. Results showed that high quality diamond was synthesized on a quasi homoepitaxial graphene substrate through sp2-sp3 hybridization and covalent bond transformation. Firstly, D peak-free graphene was synthesized on nickel metal surface. C–H and C C bonds were then exploited to produce dehydrogenation and coupling reaction which caused the transform of graphene to transform into diamond. In virtue of the superior intermiscibility and catalysis of nickel to carbon, few-layer graphene grew efficiently on nickel foil surface. An internal space microstructure network of carbon atoms was produced through different non-covalent interactions. At last, graphene is converted into diamond. This process can also be used to synthesize hydrophilic porous diamond film. It is a promising approach to the development of new graphene/diamond-based components in the future.

Highlights High-voltage aqueous supercapacitors hold promise for commercial energy storage devices due to the excellent electrochemical performance.This review summarizes the efficacious measures on boosting the cell voltage of aqueous supercapacitors from the aspects of electrode, electrolyte, and asymmetric design., Due to its ultra-fast charge/discharge rate, long cyclic life span, and environmental benignity, aqueous supercapacitor (SC) is considered as a proper next-generation energy storage device. Unfortunately, limited by undesirable water electrolysis and unreasonable electrode potential range, aqueous SC normally generates a narrow cell voltage, resulting in a low energy density. To address such challenge, enormous efforts have been made to construct high-voltage aqueous SCs. Despite these achievements, the systematic reviews about this field are still rare. To fill this knowledge gap, this review summarizes the recent advances about boosting the cell voltage of aqueous SCs. From the viewpoint of electrode, doping alkali cations, modulating the electrode mass ratio, and optimizing the surface charge density are regarded as three effective pathways to achieve this goal. However, adjusting the appropriate pH level, introducing redox mediators, and constructing “water-in-salt” electrolyte are other three universal routes from the electrolyte aspect. Furthermore, it is also effective to obtain the high-voltage aqueous SCs through asymmetric design, such as designing asymmetric SCs. The confronting challenges and future development tendency towards the high-voltage aqueous SCs are further discussed.

Electrolyte solutions and electrode active materials, as core components of energy storage devices, have a great impact on the overall performance. Currently, supercapacitors suffer from the drawbacks of low energy density and poor cyclic stability in typical alkaline aqueous electrolytes. Herein, the ultrathin Co

To provide alternative battery technologies to lithium ion battery, multivalent metal ion batteries with their high theoretical capacities and ease of preparation have gradually gained attention from both academia and industries. In this work, we report bismuth ion battery (BIB) as a promising trivalent metal ion battery, next to the only known aluminum ion battery. Our BIB successfully demonstrates battery behavior with discharge plateaus at 0.5 and 0.2 V. Gravimetric capacity of 300 mAh g-1 at current density of 0.2 A g-1 was obtained with ca. 98% coulombic efficiency. In addition, stable cyclic life was achieved after 100 cycles at 0.3 A g-1 which further suggests its suitability as potential trivalent metal ion battery.

Metal dichalcogenides have been widely investigated in various energy storage devices in the past decades due to their large interlayer spacing formed by the weak van der Waals force between the layers. Among the various metal dichalcogenides, vanadium disulphide (VS2) has recently been demonstrated as a potential cathode in zinc-ion batteries (ZIBs) exhibiting encouraging electrochemical performance and excellent reversible Zn2+ storage. However, the main challenge for VS2 is its less-than-satisfactory capacity of ca. 150–160 mA h g−1. As such, this work proposes the use of the sulphur vacancy defect engineering strategy to further enhance the electrochemical performance of VS2. The as-assembled Zn//sulphur deficient VS2 cell (denoted as D-VS2) is able to deliver a high specific capacity of 262 mA h g−1 at a current density of 0.1 A g−1, which is ca. 1.75 times higher as compared to pristine VS2, i.e., 150 mA h g−1 at 1 A g−1. Furthermore, the cyclic stability of Zn//D-VS2 is also superior as compared to its counterpart with pristine VS2 as the cathode (Zn//P-VS2). Zn//D-VS2 can achieve a capacity retention of 94% after 524 hours of continuous deep cycling, while Zn//P-VS2 can achieve only 81% retention after about 270 hours of deep cycling. Hence, based on this work, it is expected that sulphur vacancy defect engineering could be a viable strategy to enhance the electrochemical performance of not only VS2, but also of various metal dichalcogenides.

Development of efficient and durable oxygen evolution reaction (OER) catalysts has a direct impact on the water splitting efficiency and cost effectiveness. In this work, we report the successful synthesis of a new Ni(OH)2 structure, strain-stabilized Ni(OH)2 nanoribbons (NR-Ni(OH)2) two to three layers thick, with widths of 2–5 nm, via an electro-oxidation route. Conventional Ni(OH)2 usually has negligible OER activity, while NR-Ni(OH)2 shows high activity for the oxygen evolution reaction and an overpotential of 162 millivolts and furthermore exhibits long-term stability in alkaline electrolyte. The substantial reduction in the overpotential of NR-Ni(OH)2 is due to its easier OOH* adsorption by the active four-coordinated Ni edge sites. The enhanced catalytic activity of NR-Ni(OH)2 makes it an excellent candidate for industrial applications.

Aqueous rechargeable zinc-ion batteries (ZIBs) are attractive candidates for application in energy storage technology. However, the formation of Zn dendrites at a potential close to the Zn/Zn2+ redox potential can severely limit battery rechargeability and energy density. Herein, hexagonal MoO3 (h-MoO3) is proposed as an intercalation anode (discharge potential of 0.36 V (vs. Zn2+/Zn)) as a potential replacement for Zn metal plates for the first time and it showed a specific capacity of 120 mA h g−1 at 0.2 A g−1 with superior cycling stability. Furthermore, a zinc metal-free full cell was successfully demonstrated with this h-MoO3 anode and a Zn0.2MnO2 cathode. The cell delivered a specific capacity of 56.7 mA h g−1 which corresponds to an energy density of 61 W h kg−1 (based on the total mass of anode and cathode materials), higher than that of most aqueous zinc ion batteries. Furthermore, excellent cycling life was recorded as the full ZIB cell achieved ca. 100% of its original capacity after 1000 cycles. Based on the preliminary investigation of utilizing h-MoO3 as the ZIB anode, the results have shown significant promise in achieving Zn ion full batteries for energy storage applications.

Target tracking based on Siamese network has reached the state-of-the-art performance. However is still limited in semantic feature extraction. In this paper, we propose a novel method to distinguish positive and negative samples. Taking deep neural network as the backbone, we fuse the feature maps from different layers and feed it to RPN (Region Proposal Network). In addition, we use a loss term for loss function to achieve self-adjusting and learn more discriminative embedding features of target objects with similar semantics. In the tracking stage, one-shot detection is used as the reference, fix the first frame as the weight of tracking to track the subsequent frames. Our method has achieved outstanding performance on several benchmark data set, such as: OTB2015, VOT2016, VOT2018, and VOT2019 et al.

Currently, object detectors based on CNN, such as RetinaNet, Faster-RCNN, CornerNet series, can achieve good performance, but have some common drawbacks, like large calculation cost, high model complexity and slow detection speed. In this paper, a new lightweight object detector is proposed, which adopted a density-based approach to merge the real boxes. To reduce calculation cost and improve detection speed, the tactic of multi-scale output is adopted to predict objects of different sizes with features of different scales. Furthermore, a new lightweight network model is proposed, which can show better performance in computation, FPS, and model complexity. Meanwhile, the separation of convolution is used to improve the basic convolution layer, which can achieve better results under the same number of filters. In the experiments, we verified the capability of our methods based on ablation experiment and model evaluation, which demonstrates the superiority of our method. Moreover, we have also conducted deep network and multichannel experiments on MS-COCO2014 datasets and achieved 20.9% mAP performance.

Aqueous Zn/MnO

High-efficiency alkaline seawater electrolysis is a promising strategy to promote the sustainability of wide-ranging hydrogen (H2) production, and the global goal of carbon neutrality. Searching for an ideal candidate with low cost and high electrocatalytic performance for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a major objective. Herein, we report delicate, heterostuctured NiTe-NiCoN and NiTe-NiFeN electrocatalysts constructed of nickel cobalt nitride and nickel iron nitride nanosheets uniformly anchored on NiTe nanorod arrays, respectively, which ensure outstanding HER and OER activity along with ultra-long-term stability. Impressively, the NiTe-NiCoN || NiTe-NiFeN couples in alkaline seawater solution delivered 500 mA cm−2 at a record low voltage of 1.84 V, and realized an industry-level performance via a solar-powered system and a wind-power system. Further comprehensive analysis has revealed that interface engineering strategy not only ensures that the surficial nitride exposes abundant active sites, but also induces electron modulation that optimizes the binding strength of absorption/desorption for the reaction intermediates to enhanced the the intrinsic activity, as well as facilitate faster electron-mass transfer. Notably, a high electric field intensity generated by the unique nanosheet-nanorod structure induces a local “hydroxide enrichment” environment that effectively promotes the OER kinetics, while inhibits the side effects of chlorine. This work shed lights on these novel heterostructured electrocatalysts with strong synergy, while demonstrating the key role of the unique nanostructures in high-efficiency seawater electrolysis.

The electron-transfer process during the oxygen evolution reaction (OER) often either proceeds solely via a metal redox chemistry (adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level). Unlike the AEM, the LOM involves oxygen redox chemistry instead of metal redox, which leads to the formation of a direct oxygen-oxygen (OO) bond. As a result, such a process is able to bypass the rate-determining step, that is, OO bonding, in AEM, which highlights the critical advantage of LOM as compared to the conventional AEM. Thus, it has been well reported that LOM-based catalysts are able to demonstrate higher OER activities as compared to AEM-based catalysts. Here, a comprehensive understanding of the oxygen redox in LOM and all documented and possible characterization techniques that can be used to identify the oxygen redox are reviewed. This review will interpret the origins of oxygen redox in the reported LOM-based electrocatalysts and the underlying science of LOM-induced surface reconstruction in transition metal oxides. Finally, perspectives on the future development of LOM electrocatalysts are also provided.

Solar interfacial thermal evaporation system has recently drawn extensive attention because it enables low heat loss and high solar thermal conversion efficiency for water desalination and sewage treatment. However, the portability and low cost of solar thermal material are still challenges for its further practical implementation. Besides, the fundamental understanding of thermal management on the effect of efficiency remains unclear. Herein, we demonstrate a novel strategy to construct a solar thermal material of hierarchical carbon framework decorated by Fe3O4 nanoparticles (Fe3O4@CA/CF). Under 1 sun irradiation (1 kW m−2), the as-prepared absorber shows a broad spectrum absorption (∼99%) and outstanding water evaporation rate (1.316 kg m−2 h−1) with ∼91.0% efficiency, which is six times as that of water without absorber. Significantly, a marvelous volumetric water evaporation rate (up to 658 kg m−3 h−1) has been obtained, indicating its portable and cost-effective superiorities. Besides, for the first time, we quantitatively reveal a strong correlation between evaporation efficiency and porosity of 1D water path in isolation configuration through numerical simulation; the optimum range of porosity for evaporation is also identified. Combining low-cost materials, broad spectrum absorption, high solar thermal conversion efficiency and excellent portability, the as-prepared material is likely to be a promising absorber for solar interfacial evaporation system.

This paper aimed to reveal the damage mechanisms of sapphire by single grit scratch tests on C-plane, which would establish the basis of damage-free machining. The deformation and damage evolution experienced five stages with increasing cutting depth resulting from the combined effect of principle stresses and activated slip/twining systems. It was proved that subsurface and surface damages occur in ductile removal regime of sapphire, which were dominantly induced by high residual stress and the rhombohedral twinning on ( 10 1 ‾ 2 ) and ( 1 ‾ 102 ) , respectively. Three critical cutting depths for suppressing subsurface damage, surface damage and surface roughness were determined, respectively. These conclusions were also supported by the acoustic emission (AE) features both in time and frequency domains during scratching. This paper also undertook the theoretical study. An improved elastic stress field model has been established to understand the deformation and damage evolution in relation to cutting depth.