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Building change detection from very high-spatial-resolution (VHR) remote sensing images has gained increasing popularity in a variety of applications, such as urban planning and damage assessment. Detecting fine-grained ``from-to'' changes (change transition from one land cover type to another) of buildings from the VHR images is still challenging as multitemporal representation is complicated. Recently, fully convolutional neural networks (FCNs) have been proven to be capable of feature extraction and semantic segmentation of VHR images, but its ability in change detection is untested and unknown. In this letter, we leverage the semantic segmentation of buildings as an auxiliary source of information for the fine-grained ``from-to'' change detection. A deep multitask learning framework for change detection (MTL-CD) is proposed for detecting building changes from the VHR images. MTL-CD adopts the encoder-decoder architecture and solves the main task of change detection and the auxiliary tasks of semantic segmentation simultaneously. Accordingly, the change detection loss function is constrained by the auxiliary semantic segmentation tasks and enables the back-propagation of the building footprints' detection errors for the improvement of change detection. A building change detection data set named the Guangzhou data set is also developed for model evaluation, in which the bitemporal R-G-B images were collected by airplane (2009) and unmanned aerial vehicle (UAV, 2019) with different flight heights. Experiments on the Guangzhou data set demonstrate that the MTL-CD method effectively detects fine-grained ``from-to'' changes and outperforms the postclassification methods and the direct change detection methods.

In the continuous development of electrochemical CO2 reduction (ECR), Cu-based electrocatalysts have received great attention, due to their unique ability to produce high value-added multicarbon products. Of particular interest are various Cu-comprising nanocrystals, not only because they usually show better catalytic properties than bulk materials, but also because their well-defined structures and highly tunable compositions facilitate in-depth mechanistic studies. This review aims to summarize the latest developments of electrocatalysts for ECR, with a focus on systems using Cu-comprising nanocrystals. We first give a general introduction to the field of ECR, covering the significance of this process, reaction mechanisms, catalyst evaluation criteria, and electrolytic cell configurations. Next, we discuss Cu-comprising nanocrystals developed for ECR by categorizing them into four groups: monometallic copper, copper-containing bimetals/multimetals, copper compounds, and copper–metal oxide hybrids; among these groups, we choose representative examples for detailed discussion on the synthetic methods, structural and compositional reaction sensitivities, and catalyst evolution during ECR. In the last section, we outline the challenges in this field from the fundamental and applicative aspects, and give perspectives on the expansion of catalyst varieties, the identification and preservation of active sites, and the exploration of industrially relevant operations for these nanocrystals. We hope the insights provided in this review will inspire the design and development of next-generation catalysts for ECR.

Titanium dioxide is often used to capture polysulfides due to its strong surface polarity. Surface activity of titanium dioxide is produced by defects, which possesses an important impact on abilities to capture polysulfides. However, the reaction mechanism of defective titanium dioxide in the process of capturing polysulfide is not clear. In this paper, we introduced cobalt source as an additive to titanium dioxide/biomass carbon composite materials to prepare titanium dioxide with many defects and strong surface activities. The crystallinity of biomass carbon surface is also continuously improved by introducing cobalt sources. Under combined performance of highly active titanium dioxide and highly conductive biomass carbon, composite materials possess strong and reversible polysulfide-capturing abilities. In particular, types of polysulfides captured is increased. Herein, the addition of cobalt source is beneficial to enhance abilities of titanium dioxide to capture multiple polysulfides, improve conductivity of composite materials and achieve high reversible capacity (375.0 mA h·g−1 after 500 cycles at 1C).

Construction of Z-scheme heterostructure is of great significance for realizing efficient photocatalytic water splitting. However, the conscious modulation of Z-scheme charge transfer is still a great challenge. Herein, interfacial Mo-S bond and internal electric field modulated Z-scheme heterostructure composed by sulfur vacancies-rich ZnIn2S4 and MoSe2 was rationally fabricated for efficient photocatalytic hydrogen evolution. Systematic investigations reveal that Mo-S bond and internal electric field induce the Z-scheme charge transfer mechanism as confirmed by the surface photovoltage spectra, DMPO spin-trapping electron paramagnetic resonance spectra and density functional theory calculations. Under the intense synergy among the Mo-S bond, internal electric field and S-vacancies, the optimized photocatalyst exhibits high hydrogen evolution rate of 63.21 mmol∙g−1·h−1 with an apparent quantum yield of 76.48% at 420 nm monochromatic light, which is about 18.8-fold of the pristine ZIS. This work affords a useful inspiration on consciously modulating Z-scheme charge transfer by atomic-level interface control and internal electric field to signally promote the photocatalytic performance. The construction of Z-scheme heterostructures is of great significance for realizing efficient photocatalytic water splitting. Here, the authors report an interfacial chemical bond and internal electric field modulated Z-Scheme Sv-ZnIn2S4/MoSe2 photocatalyst for efficient hydrogen evolution.

The intrinsic activity of catalysts is crucial for the electrocatalytic hydrogen evolution reaction, which is essentially dependent on their crystal structure and surface electronic state. The vari...

A covalently bonded 3-aminopropyltriethoxysilane (APS)-TiO2 nanorods-woven carbon fiber (WCF) was designed though the in-situ hydrothermal growth followed by the chemical grafting. The silanization for TiO2 nanorods-WCF improved both the mechanical interlocking and chemical interaction among TiO2 nanorods, carbon fiber and phenolic, as well as the interfacial bonding between TiO2 nanorod and carbon fiber, thus formed an effective transition interface. The designed WCF offered a 157.1% increase of tensile strength compared to the desized-WCF. Moreover, the optimized interfacial binding and Si-based transfer film on worn surface leaded to the increased frictional coefficient and a 63.0% decrease of wear rate for composite under sliding frication. The APS-TiO2 nanorods-woven carbon fiber was proven to be an advanced reinforcement for wear-resistance phenolic composite.

Iron carbodiimide (FeNCN) belongs to a type of metal compounds with a more covalent bonding structure compared to common transition metal oxides. It could provide possibilities for various structural designs with improved charge-transfer kinetics in battery systems. Moreover, these possibilities are still highly expected for promoting enhancement in rate performance of sodium (Na)-ion battery. Herein, oriented FeNCN crystallites were grown on the carbon-based substrate with exposed {010} faces along the [001] direction (O-FeNCN/S). It provides a high Na-ion storage capacity with excellent rate capability (680 mAh g-1 at 0.2 A g-1 and 360 mAh g-1 at 20 A g-1), presenting rapid charge-transfer kinetics with high contribution of pseudocapacitance during a typical conversion reaction. This high rate performance is attributed to the oriented morphology of FeNCN crystallites. Its orientation along [001] maintains preferred Na-ion diffusion along the two directions in the entire morphology of O-FeNCN/S, supporting fast Na-ion storage kinetics during the charge/discharge process. This study could provide ideas toward the understanding of the rational structural design of metal carbodiimides for attaining high electrochemical performance in future.

The conversion chemistry of lithium–sulfur provides a high energy density (2600 Wh/kg), enabling lithium–sulfur batteries to be a promising energy storage system. Nevertheless, the dissolved lithiu...

To meet the ever-increasing demand for higher energy density and power density, developing cathode materials with high specific capacity has become an urgent problem. V2O5 has been considered as one of the most promising cathodes for its high theoretical specific capacity (443 mAh g−1), abundant source, and low cost. In this work, cobalt-doped vanadium pentoxide (Co-V2O5) microflowers were synthesized through a simple solvothermal method. The doped Co not only improves the electronic conductivity but also increases the diffusion coefficient of the lithium ions. Benefiting from the appropriate amount of Co doping, the charge transfer impedance decreases from 51 to 28 Ω and the diffusion coefficient of the lithium ions increased from 2.81×10−17 cm2 s−1 to 3.31×10−16 cm2 s−1. The optimal Co-V2O5 microflowers deliver a high reversible capacity of 166 mAh g−1 after 200 cycles.

The rational design and construction of noble-metal-free electrocatalysts with high activity and robust durability for oxygen evolution reactions (OERs) have aroused immense interest in the past decades, but challenges remain. Herein, a reduction-induced dissolution–recrystallization (RIDR) strategy was developed to fabricate a defect-rich yolk–shell Prussian-blue analogue (YS-PBA) by a solvothermal process in isopropyl alcohol (IPA) in the presence of polyvinylpyrrolidone (PVP). The experimental result indicated that the defect-rich YS-PBA was formed via phase transformation from Co3[FeIII(CN)6]2 to Co2FeII(CN)6 induced by the reduction potential of the IPA-PVP couple. The newly synthesized YS-PBA exhibited outstanding OER performance with a low overpotential of 293 mV to deliver a current density of 10 mA cm−2 and long-term durability (120 h) in alkaline media. Both experimental and density functional theory (DFT) results unveiled that the defects formed in YS-PBA cause a dramatic positive effect on the improvement of the OER activity.

The recent applications of fully convolutional networks (FCNs) have shown to improve the semantic segmentation of very high resolution (VHR) remote-sensing images because of the excellent feature representation and end-to-end pixel labeling capabilities. While many FCN-based methods concatenate features from multilevel encoding stages to refine the coarse labeling results, the semantic gap between features of different levels and the selection of representative features are often overlooked, leading to the generation of redundant information and unexpected classification results. In this article, we propose an attention-guided label refinement network (ALRNet) for improved semantic labeling of VHR images. ALRNet follows the paradigm of the encoder-decoder architecture, which progressively refines the coarse labeling maps of different scales by using the channelwise attention mechanism. A novel attention-guided feature fusion module based on the squeeze-and-excitation module is designed to fuse higher level and lower level features. In this way, the semantic gaps among features of different levels are declined, and the category discrimination of each pixel in the lower level features is strengthened, which is helpful for subsequent label refinement. ALRNet is tested on three public datasets, including two ISRPS 2-D labeling datasets and the Wuhan University aerial building dataset. Results demonstrated that ALRNet had shown promising segmentation performance in comparison with state-of-the-art deep learning networks. The source code of ALRNet is made publicly available for further studies.

Both biomass carbon and titanium dioxide are beneficial for enhancing the capturing capacities and conversion capacities of polysulfides and achieving excellent lithium–sulfur battery performance. However, the binding ability between highly polar titanium dioxide and weakly polar biomass carbon is weak. The sulfur-loading capacity of titanium dioxide/biomass carbon composite structures is limited and a large number of polysulfides produce shuttle effects. How to enhance the binding ability of titanium dioxide and biomass carbon to achieve high sulfur-loading is an issue that needed to be solved. In this paper, we introduce cobalt into the surface of titanium dioxide/biomass carbon composite structures, adjust the cobalt–titanium molar ratio and obtain composite structures with the strongest binding abilities. The composite structure has high specific capacity and good cycling stability. After 500 cycles at 1.7 A g−1, the reversible capacity is still close to 400 mA h g−1. The high capacity and good cycling stability depend on the ability of composite structures to capture multiple polysulfides and achieve reversible conversion.

The development of low-cost and high-efficient electrocatalysts toward hydrogen evolution reaction (HER) is highly desirable and challenging. Herein, the novel V-doped Ni3S2/NiS heterostructure nanorod arrays grown on nickel foam (VNS/NF-WM) are synthesized via a facile methanol-assisted hydrothermal method. We demonstrate that the morphology, phase composition, and crystallinity of VNS/NF are well modulated by tuning the ratios of water/methanol solvent. The optimized VNS/NF-WM-heterostructured nanorod (volume ratio of water/methanol is 3:1) exhibits superior HER electrocatalytic activity with low overpotentials of 85 and 218 mV to yield current density values of 10 and 100 mA cm-2, respectively, meanwhile sustaining an excellent stability with almost an unchanged current density of 10 mA cm-2 for 60 h. Our work offers fresh insights into the rational design of highly active and stable earth-abundant-heterostructured electrocatalysts for the hydrogen fuel production.

Ablation of carbon/carbon (C/C) composites was investigated in a nitrogen plasma torch with a heat flux of ∼25 MW/m2. The reaction products of carbon in C/C composites and nitrogen plasma jet were calculated based on the principle of free energy minimum. The calculated results show that the thermal chemical ablation and sublimation of carbon occur and Cn(g) (n = 1–3), CN(g), C2N(g) and C2N2(g) may be the major reaction products consuming carbon. Ablation is apt to begin at the interfaces, especially the fibre-matrix interface and interfaces inside the matrix. Ablation of C/C composites is mainly controlled by the thermal chemical ablation, sublimation of carbon, and mechanical breakage. The formation of needle-shaped fibres and shell-shaped matrices is attributed to both the thermal chemical ablation and sublimation of carbon, while carbon fragments and fractured fibres or matrices result from the mechanical breakage.

A green and natural biomass carbon with hollow structure was first reported derived from waste makeup cotton, which was prepared by facile pyrolysis and carbonisation in the nitrogen-filled vacuum tube furnace. Utilised as lithium-ion batteries (LIBs) anode materials, the hollow structure exhibits superior cycling and rate performance. At the current density of 100 mA g−1, it demonstrates a reversible capacity of 340 mAh g−1 with the Coulombic efficiency of 58.8%, and the reversible capacity gradually increases to 450 mAh g−1 at 300 cycles, displaying long cycling stability. Even at a higher current density of 500 mA g−1, the capacity can be maintained around 245 mAh g−1 after 150 cycles. Moreover, the hollow carbon exhibits excellent rate capability (222 mAh g−1 at an ultrahigh rate of 2000 mA g−1). This enhanced property can be attributed to its special hollow structure, which could provide fast lithium ions and electrons transfer path to facilitate the electrochemical reaction. The authors believe this work could help to design new carbon materials with green and environmental protection as anode materials for LIBs.

Polysulfides (Li2Sx) have become key points that limit capacity improvement of lithium-sulfur batteries because of their high solubility. Oxygen-containing functional groups (such as C–O–H, C–O–C and C O) can effectively relieve a large amount of polysulfide dissolution due to their strong polarity. However, their types and contents on polysulfide-capturing abilities are still unknown. Therefore, three kinds of electrodes containing different contents of hydroxyl (C–O–H), ether (C–O–C) and carbonyl (C O) groups on carbon surface are controlled by changing pyrolysis times of dandelion. Electrochemical performance of lithium-sulfur batteries is tested to analyze influence of these groups on polysulfide-capturing abilities. It is discovered that C O and C–O–H groups can obviously inhibit shuttle effects of polysulfides during their initial production. In addition, a large number of C O bonds are converted to C–O–H bonds. More C–O–H bonds facilitate reversible capture of polysulfides and improve capacities. The introduction of C–O–C groups is not suitable for capturing more polysulfides rapidly and the appearance of ether groups limits conversion process of C–O–H groups. Both S load and discharging/charging process can effectively regulate evolution of three valence bonds, which is conducive to improving rate performance of lithium-sulfur batteries.

We report the in situ generation of NiCoV-LTH (layered triple hydroxide) on nickel foam (NF) for electrocatalytic oxygen evolution reaction (OER). By adjusting the molar ratio of Co/V, the NiCoV-LT...

The hydrophilicity/hydrophobicity of zeolites has been received increasing attentions due to its great influence on the physical, chemical property and application of zeolites. Generally, zeolites ...

The vital challenge of a layered manganese oxide cathode for sodium-ion batteries is its severe capacity degradation and sluggish ion diffusion kinetics caused by irreversible phase transitions. In response to this problem, the spinel-layered manganese-based composite with an intergrowth structure is ingeniously designed by virtue of an interesting spinel-to-layered transformation in the delithiated LiMn2O4 under Na+ insertion. This unique spinel-layered intergrowth structure is strongly confirmed by combining multiple structure analysis techniques. The layered component can provide more reversible capacity, while the spinel component is crucial for the stabilized crystal structure and accelerated ion diffusion kinetics. As an appealing cathode for sodium-ion batteries, the layered-spinel composite delivers a high reversible capacity of 180.9 mAh g-1, excellent cycling stability, and superior rate capability with 55.7 mAh g-1 at 12 C. Furthermore, the reaction mechanism upon Na+ extraction/insertion is revealed in detail by ex situ X-ray diffraction and X-ray photoelectron spectroscopy, indicating that Na+ ions can be accommodated by the layered structure at a low voltage and by the spinel at a high voltage. This study will provide a new idea for the rational design of an advanced cathode for sodium-ion batteries.

Developing the highly active, cost-effective, environmental-friendly, and ultra-stable nonprecious electrocatalysts for hydrogen evolution reaction (HER) is distinctly indispensable for the large-scale practical applications of hydrolytic hydrogen production. Herein, we report the synthesis of well-integrated electrode, NiV layered double hydroxide nanosheet array grown in-situ on porous nickel foam (abbreviated as in-NiV-LDH/NF) via the facile one-step hydrothermal route. Interestingly, the valence configuration of vanadium (V) sites in such NiV-LDH are well dominated by the innovative use of NF as the reducing regulator, achieving the reassembled in-NiV-LDH/NF with a high proportion of trivalent V ions (V3+), and then an enhanced intrinsic electrocatalytic HER activity. The HER testing results show that the in-NiV-LDH/NF drives the current densities of 10 and 100 mA cm−2 at extremely low overpotentials of 114 and 245 mV without iR-compensation respectively, even outperforms commercial 20 wt% Pt/C at the large current density of over 80 mA cm−2 in alkaline media, as well as gives robust catalytic durability of at least 100 h in both alkaline and neutral media. More importantly, this work provides a fresh perspective for designing bimetal (oxy) hydroxides electrocatalysts with efficient hydrogen generation.

Self-assembled cactus-like NH4V3O8 is prepared through polyethylene glycol (PEG)-assisted hydrothermal synthesis method. The samples are characterized by X-ray diffraction and scanning electron microscopy techniques. Adjusting the pH value of the solution can effectively control the morphology of NH4V3O8. The electrochemical measurements indicate that the sample which pH value is 3.7, shows the best cycling performance. It delivers an initial discharge capacity is 228 mAh g−1 and maintains at 156 mAh g−1 under 15 mA g−1 after 50 cycles. The proposed synthetic method can also be developed to address other electrode materials with inferior electronic conductivity and lithium ion diffusion.

A novel blue-emitting Mg₂La8(SiO₄)6O₂:Ce3+ phosphor with apatite-type nanostructure has been successfully synthesized via a conventional solid-state reaction. X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. The phosphor exhibited an absorption band ranging from 220 to 400 nm in the ultraviolet range and generated bright blue emission at 425 nm and 510 nm under different excitation wavelengths. The critical Ce3+ quenching concentration (QC) was determined to be about 7 mol%, and the corresponding QC mechanism was verified to be the dipole-dipole interactions.

Developing highly efficient electrocatalysts with hierarchical structures while revealing their electrochemical reaction mechanism is crucial for pushing commercial water splitting application. Her...

Metal–organic frameworks (MOFs) with a high density of metal nodes have great potential in the application of heterogeneous catalysis. However, identifying the real active site in MOF structures and tuning its amount to further improve its catalytic performance are still a great challenge. In this paper, defective UiO-66 modulated with trifluoroacetic acid (TFA) was synthesized and used for the conversion of cyclohexanone to cyclohexanol via hydrogen transfer. We found that not all structural defects were responsible for catalytic reaction, and only structural defects where open metal sites are created by a modulator were effective for cyclohexanone conversion. Then we successfully tuned the number of each type of effective structural defect (that is, missing-cluster defects or missing-linker defects) in modulated UiO-66 via precise control of the synthetic/treatment conditions. Our experimental results showed that the creation of both types of structural defects can increase the amount of effective open metal sites and then enhance their catalytic performances under the same conditions. Furthermore, the mechanism study confirmed that this reaction indeed proceeded on effective open metal sites. Our findings have further deepened the understanding of the roles of structural defects in MOF heterogeneous catalysis.

Polymeric membranes with high ionic conductivity and solvent molecule blocking capability are attracting considerable attention as separators for new-generation batteries adopting hybrid electrolytes. The performances of the membranes are closely dependent on their microstructures and functional groups. Here, we report the design and fabrication of a carboxyl-functionalized polymer-of-intrinsic-microporosity (PIM) membrane, which has optimal surface properties and microporous channels (∼0.8 nm) to permit cation (Li+ or Na+) transportation, while preventing solvent molecule penetration. Using a droplet-templating strategy, we create large pores on both surfaces of the PIM-membrane to improve its interfacial contact with electrolytes. The obtained membrane integrates good mechanical strength with high thermal and electrochemical stability, demonstrating a great potential for battery applications as a flexible separator. When intercalated with Li+, the membrane (PIM-1-COOLi) exhibits a remarkable Li+ conductivity in both aqueous (6.5 × 10−3 S cm−1) and organic (7.3 × 10−4 S cm−1) solutions, as well as a good solvent permeation resistance (19 μmol cm−2 min−1 at 10 Pa for H2O). Taking these advantages of the PIM-membrane, we are able to fabricate challenging batteries with hybrid electrolytes, such as Li–H2O2 and Na–H2O2 batteries (Li/Na anode with organic electrolyte and H2O2 cathode with aqueous electrolyte), into a flexible laminated form. The as-fabricated battery shows an excellent discharge performance, comparable to a model battery constructed with the commercial ceramic Li super-ionic conductor, but is more tolerant to mechanical treatment and harsh environment. Our study demonstrates that PIM represents a promising platform for developing flexible secondary batteries with hybrid electrolytes, which are particularly desirable for wearable and portable electronic devices.

Developing 3 D self-assembled nanoarchitectures with well-defined crystal structures is an effective strategy to enhance the electrochemical performances of electrode materials. (1 1 0)-oriented and bridged-nanoblocks self-assembled VS4 microspheres are controllably synthesized by a facile one-step hydrothermal method. The (1 1 0)-bridged structure sets up open pathways for Na+ diffusion among nanoblocks, and the (1 1 0)-oriented structure provides unobstructed pathways for Na+ diffusion in the nanoblocks, which collectively constructs multidimensional Na+ transfer channels in the VS4 microspheres, promoting the electrochemical kinetics. As an anode for Na-ion batteries (SIBs), this material exhibits pseudocapacitive Na+ storage and excellent rate capability, delivering high capacities of 339 and 270 mAh g-1 at rates of 0.1 and 2.0 A g-1 , respectively, with a capacity retention of 79 % in the voltage window of 0.5-3.0 V. In particular, the reversible capacity reaches 575 mAh g-1 after 300 cycles even at 1.0 A g-1 in the voltage window of 0.05-3.0 V, outperforming those of the ever-reported VS4 -based anode materials. This work presents an effective strategy to the exploration and design of high-performance anodes for SIBs.

Microparticles with carbon microsphere (CMS) cores and poly(methyl methacrylate) (PMMA) shells were successfully synthesized through an aqueous-phase radical polymerization method. The morphologies...

Classification of species at the individual tree level would be beneficial to many applications including forest landscape visualization, forest management, and biodiversity monitoring. This article develops a patch-based classification algorithm of individual tree species based on convolutional neural network. The individual trees are first detected using the local maximum method from the canopy height model, as derived from light detection and ranging (LiDAR) data. The detected individual trees are then cropped into patches for classification based on the tree apexes, and three spatial scale image patches are chosen for analysis and discussion. A modified ResNet50 deep network is further employed for the cropped individual tree patches classification. The patch-based method accounts for the contexture information of a tree and does not require the feature selection or the feature reduction processes. About 1388 training samples including Ficus microcarpa Linn. f., Delonix regia , Chorisia speciosa A.St.-Hil., Dimocarpus longan Lour., Musa nana Lour., Carica papaya , and Others (the other tree species except the above six) were collected from both field work and visual interpretation. Aerial images, LiDAR data, and Worldview images were used for the tree species classification. For 362 test tree samples, the results of patch size 64 achieve the best accuracies, and the proposed method outperforms the traditional machine learning method with the overall accuracy of 89.06% + 0.58% using aerial images only. Transferability Study to the Luhu Park also indicated the feasibility of our method. While challenges in individual tree detection and multisource data fusion remain, the solution shows the potential in characterizing tree species at the individual tree level using remote sensing data.

The ability to construct magnetic self-assembling architectures in carbon materials offers a novel and extremely tantalizing route towards spintronics, both from fundamental and application points ...

Building Chemical bonds is an effective strategy to obtain excellent performance of electrode materials. Herein, we report SnSe nanoparticles growth on carbon nanotubes (SnSe-CNTs) composite with strong Sn C bonding for high performance LIBs anode. The composite electrode exhibits high reversible capacity of 772 mAh g−1 after 200 cycles at a current density of 200 mA g−1. Even under higher current density of 1 A g−1, the capacity of composite electrode still maintains 323 mAh g−1 after 1000 cycles, the capacity retention rate is as high as 69.5%. It is found that strong electronic coupling between SnSe nanoparticles and carbon nanotubes conducive to the rapid transmission of electron/ion, facilitating the reversible conversion reaction between Sn and Li2Se to form SnSe. Meanwhile, Sn C bonding significantly improved structural stability of SnSe nanoparticles growth on carbon nanotubes composites electrode. These encouraging results of chemical bonding provide new opportunities for designing advanced electrode materials.

Transition oxides are a kind of promising anode materials for lithium-ion batteries due to their high capacity and low cost. However, it is a great challenge to realize high power density and long cycle life. Size control and surface coating are effective ways to increase reaction sites and improve electrical conductivity. In this work, rice crust-like structure of thin carbon layer coated Fe3O4 nanoparticles (∼15 nm) uniformly covering rGO sheets (Fe3O4@C/rGO) is achieved. This composite delivers a high capacity of 594 mAh g−1 even after 1000 cycles at a high current rate of 5.0 A g−1, which can be attributed to the high surface pseudocapacitance dominated storage mechanism. Further analysis reveals that the high extrinsic pseudocapacitance is closed to the nanosized structure and carbon coating, because large surface area and good electrical conductivity are essential for the improvement of extrinsic pseudocapacitance. This work offers a new perspective for future structure design for high-rate and long-life anode materials of lithium-ion batteries.

In this work, the monoclinic and hexagonal phase of WO3 nanocrystallines are prepared by a facile one-pot microwave assisted hydrothermal method. The obtained WO3 are fabricated as gas sensors to detect acetone vapor. The microstructure and sensing performances of different WO3 phases are studied comparatively. The results show that the precursor pH value affects precipitation of H2WO4 and subsequently decomposition of H2WO4 to WO3. Hydrochloric acid plays very important role both in adjusting pH and modulating WO3 morphology. The monoclinic WO3 with oxygen vacancy exhibits outstanding high sensitivity and fast response to a wide concentration range of acetone (0.25 ppm–100 ppm). The response value reaches 3.8–250 ppb, and 31–100 ppm respectively, at optimal working temperature of 320 °C. The detection limit is estimated as low as 7.5 ppb. The excellent sensing performance of the monoclinic WO3 is attributed to the lattice oxygen defects which facilitate acetone adsorption on the material surface. Furthermore, the strong dipole moment interactions between monoclinic WO3 and acetone molecules help enhancing the selectivity.

Nanorod assembled three-dimensional (3D) hierarchical Zn0.2Cd0.8S microspheres were successfully prepared by a facile one-pot microwave hydrothermal approach using ethylenediamine (EN) as a template agent. The optimal 3D hierarchical Zn0.2Cd0.8S microspheres (ZCS-30) is obtained when adding 30 mL into the synthetic system, which can function as a highly active photocatalyst for H2 evolution under visible-light irradiation with the wavelength of 420 nm, delivering an activity approximately 2.5 and 7.5 times higher than that of Zn0.2Cd0.8S nanoparticles and CdS counterparts, respectively, and giving an apparent quantum efficiency (AQE) of 7.4%. Furthermore, the ZCS-30 photocatalyst shows the good stability after the catalytic H2 evolution for 15 h (5 cycles). In addition, the ZCS-30 photocatalyst exhibits the excellent degradation of Rhodamine B (Rh B) almost up to 80% under the visible light irradiation over a period of 150 min. The results demonstrate that ZCS-30 can serve as a promising visible-light-driven bifunctional photocatalyst for water splitting and dye degradation.

Oxygen-containing functional groups and pseudographic structure are key factors that affect the electrochemical properties of biomass derived carbon materials. In this work, the shaddock peel derived hard carbon with abundant carbon-oxygen double bond (C O) and highly ordered pseudographic structure is successfully synthesized by a H2SO4-assisted hydrothermal pretreatment and subsequent KOH-assisted low temperature (600 °C) pyrolysis procedure. The resulting unique structure is beneficial for the co-effective enhancement of Na+ storage sites and electrochemical reaction kinetics. The hard carbon exhibits excellent cycling and rate performances in sodium-ion batteries, delivering a high reversible capacity of 380 mAhg−1 at 50 mAg−1 after 500 cycles, and that of 274 and 199 mAhg−1 even at 500 and 1000 mAg−1, respectively. This performance is superior to the previously reported shaddock peel derived hard carbons. Besides, the surface-controlled redox mechanism of C O and Na+ occurring at the hard carbon is clearly revealed.

This paper compares several kinds of methods for motor speed synchronization control, which plays an important role in gear shifting of emerging clutchless automated manual transmissions for battery electric vehicles and other powertrain systems for hybrid electric vehicles. Specifically, four controllers, namely, proportional-integral control, disturbance observer–based proportional control, integral sliding mode–based proportional control, and disturbance observer–based act-and-wait control, are compared in transient responses regarding settling time, overshoot, and steady-state error. Each is formulated by combining one nominal controller for speed tracking and another for disturbance compensation. For disturbance observer–based proportional control, model-based determination of the feedback gain and disturbance observer gain is discussed. Simulations and experiments are carried out to study effects of different controller parameter settings and evaluate performances of different methods under different operation conditions with disturbances and uncertainties like plant parameter drift, communication time delay, unknown load torques, and so on. Based on the results, it is advised that disturbance observer–based proportional control with the reference signal set as the nominal speed trajectory be used in practice, since it comes with merits of few controller parameters to be determined as well as robust, consistent, and satisfactory performances.

The product selectivity in the electrochemical reduction of carbon dioxide depends on the structure of the copper electrode. Cube-shaped copper catalysts, enclosed by {100} terraces, {110} edges, a...

Hydrophilicity/hydrophobicity property of zeolite has been received much attention in recent years. Regulation of hydrophilicity/hydrophobicity of zeolite using relative simply process and cheap raw materials is needed to be further investigated and solved. The aim of this study is to investigate effect of acid and alkali treatments on structure, hydrophilicity/hydrophobicity of natural zeolite. The structure of the samples was characterized using ICP, XRF, XRD, laser particle size analyzer, N2 adsorption-desorption, XPS, SEM-EDX, etc. The hydrophilicity/hydrophobicity of the samples was determined using water vapor adsorption method coupled with BET specific surface area results. The results showed that acid treatment removed 5.05–23.26 wt% of aluminum from the framework of clinoptilonite using 0.1–3 M nitric acid while alkali treatment removed 0.49–7.64 wt% of silicon from the framework of clinoptilonite using 0.05–0.8 M sodium hydroxide. Accompanied by the removal of Al and Si, the specific surface area of zeolite obviously increased and decreased, respectively. Water vapor adsorptions on the alkali and acid treated zeolites with ascending SiO2/Al2O3 ratio gradually decreased which confirmed the increase of hydrophobicity and decease of hydrophilicity for the samples. This acid/alkali treatment method appears to be a simple and effective way to regulate hydrophilicity/hydrophobicity of natural zeolite.

A novel method is proposed to chemically graft 3-aminopropyltriethoxysilane (APS) onto the MnO2 nanosheets which grown on woven carbon fiber (WCF), forming the CF-MnO2-APS hierachical reinforcement, as confirmed by FTIR, EDS and XPS. The flexural and tensile strength of corresponding composite are 150.4 MPa and 292.3 MPa, for an increase of 46.9% and 31.7%, respectively. Besides, the composite displays the optimal anti-wear under various applied load. Our work finds that grafting APS onto MnO2 nanosheets is the major reason for forming chemical bonding at fiber/matrix interface. Overall, the synergetic effects of mechanical interlocking and chemical bonding at interface are primary in improving the comprehensive properties of composites.

In this article, nitrogen is successfully doped into both components of TiO2/reduced graphene oxide composites via a hydrothermal-post thermal treatment. The N-doped TiO2/reduced graphene oxide electrode presents obviously higher Li-ion storage performance (270 mAh g−1 at current density of 0.1 A g−1) than the undoped product. This N-doped composite could also exhibit superior long-term cycling stability with a reversible capacity of 210 mAh g−1 even after 2000 cycles. Further electrochemical analysis finds the number of active Li-ions is increased from the formation of N Ti O and N C bonds, which greatly improves the charge/discharge process in the anode for lithium-ion batteries. This work may improve understanding of the doping effects of various elements present in electrode materials.

The binding configurations of the nitrogen have a great influence on the performance of the doped graphene-based lithium ion batteries anode, while the mechanism of lithium storage is still unclear. In this paper, the binding configuration of the nitrogen is controlled in doped graphene by introducing little sulfur atoms to produce more proportion of graphite nitrogen, which have an excellent cyclic performance with delivering 589 mAh g−1 at 5 A g−1 after 1000 cycles in the lithium ion batteries anode. What's more, the kinetics is improving with higher lithium ion diffusion coefficient and a smaller impedance of charge-transfer compared to the samples which do not regulated the binding configurations of the nitrogen. The characteristic electronic structure of graphite nitrogen is considered to reveal the lithium storage mechanism. Consequently, this work can provide a new insight for regulating binding configurations of nitrogen to improving lithium storage kinetics of the doping graphene electrodes.

Automated extraction of buildings from remotely sensed data is important for a wide range of applications but challenging due to difficulties in extracting semantic features from complex scenes like urban areas. The recently developed fully convolutional neural networks (FCNs) have shown to perform well on urban object extraction because of the outstanding feature learning and end-to-end pixel labeling abilities. The commonly used feature fusion or skip-connection refine modules of FCNs often overlook the problem of feature selection and could reduce the learning efficiency of the networks. In this paper, we develop an end-to-end trainable gated residual refinement network (GRRNet) that fuses high-resolution aerial images and LiDAR point clouds for building extraction. The modified residual learning network is applied as the encoder part of GRRNet to learn multi-level features from the fusion data and a gated feature labeling (GFL) unit is introduced to reduce unnecessary feature transmission and refine classification results. The proposed model - GRRNet is tested in a publicly available dataset with urban and suburban scenes. Comparison results illustrated that GRRNet has competitive building extraction performance in comparison with other approaches. The source code of the developed GRRNet is made publicly available for studies.

Ultrafine SnSe nanocrystals uniformly dispersed on the reduced graphene oxide (r-GO) surface were synthesized by a facile one-step solvothermal technique. The as formed SnSe with size less than 5 n...

A flexible NiCo2O4@Carbon/Carbon nanofiber (NiCo2O4@C/CNFs) composite was fabricated by the combined electrospray/electrospinning technique. The NiCo2O4 clusters were coated with an amorphous carbon layer to form NiCo2O4@C core-shell structure and homogeneously trapped in the CNFs net. The NiCo2O4@C/CNFs electrodes exhibited a high specific capacitance (1586 Fg−1 at 1 Ag−1), good rate performance (51% retention even at 32 Ag−1), and superior cycling life (92.5% capacitance retention after 5000 cycles at 10 Ag−1). The combined electrospray/electrospinning technique is a promising method to produce flexible electrodes with enhanced performance.

Combination of lightweight and superior electrical conductive performance is charming for the application of macroscopic graphene foam composite. A porous carbon nanotubes/reduced graphene oxide (CNTs/RGO) foam composite are prepared by freeze-drying and in-situ catalytic grown methods. The CNTs/RGO foam composite consists of interconnected RGO nanosheets as the 3D frame and in-situ growth CNTs as the electromagnetic wave (EM) absorbing reinforcement, which grow on graphene substrate. The in-situ grown CNTs on graphene nanosheets lead to the enhancement of conductive and polarization loss, which results in the enhancement of absorption shielding performance. The CNTs/RGO foam composites with different CNT loading are prepared to investigate their EM shielding properties in X-band. The EM shielding effectiveness (SE) of CNTs/RGO foam composite reaches 31.2 dB with 2 mm thickness, especially the specific EMI shielding effectiveness reaches 547 dB cm3/g with an ultralight density of 57 mg cm−3, the absorption is the primary shielding mechanism. Furthermore, SE value reaches 49 dB with thickness of 3.1 mm. Owing to the unique 3D foam hierarchical architecture, light density and outstanding SE performance, our work shows a promising designable approach of preparing CNTs/RGO foam composite to lightweight and absorption type EMI shielding materials.

In this study, SnNb2O6 and Sn2Nb2O7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb2O6 electrode exhibits high reversible capacity and excellent cycling stability (498 mAh/g at 0.1 A/g after 100 cycles), which is superior to that of Sn2Nb2O7 electrode (173 mAh/g at 0.1 A/g after 100 cycles). Even increasing the current density to 2.0 A/g, the SnNb2O6 electrode still delivers a reversible capacity up to 306 mAh/g. The rate performance of the SnNb2O6 electrode is also better than that of Sn2Nb2O7 electrode at different current densities from 0.1 A/g to 2.0 A/g. The enhanced electrochemical performance of SnNb2O6 nanosheets can be attributed to the unique layered structure, which is conducive to the diffusion of the lithium ions and the migration of electrons during discharge/charge.

As an anode material for lithium ion batteries, metal vanadates undergo structure variation in the lithiation process. In the case of copper pyrovanadate (Cu2V2O7), it would decompose to be amorphi...

In this paper, the platelike K0.8Fe0.8Ti1.2O4 particle with layered structure was synthesized in the hydrothermal system of TiO2, Fe(NO3)3 and KOH at 250 °C. The hydrothermal temperature and the KOH concentration are crucial in the formation of K0.8Fe0.8Ti1.2O4 phase. The platelike K0.8Fe0.8Ti1.2O4 particle had the size of ∼3 μm in width and 50 nm in thickness. Meanwhile, the electrochemical performance of K0.8Fe0.8Ti1.2O4 as lithium ion battery anode materials was investigated for the first time.

Designing and manufacturing a novel structural the composite electrode materials can effectively improve the electrochemical performance of lithium ion battery. Hence, in this work, hierarchical nanoflower SnS2 anchored on g-C3N4 nanosheets (the SnS2/CN composite) electrode was creatively synthesized by a facile microwave hydrothermal method. The SnS2/CN composite exhibits excellent cyclic stability, high-rate capacity and structural integrity at higher current density for lithium ion battery. It delivers high discharge capacity of 444.7 mAh·g−1 at a current density of 100 mA g−1 after 100 cycles with the coulombic efficiency of over 99.9%, high specific capacity retention rate at higher current density (383.8 mAh·g−1 and 350.8 mAh·g−1 at the current density of 800 mA g−1 and 1000 mA g−1, respectively). The remarkable electrochemical performances of the SnS2/CN composite electrode are attributed to its large surface area which provides more active sites and accelerates the migration of electrons and lithium ions during charge/discharge cycles. Moreover, the synergistic effect of the g-C3N4 nanosheets and nanoflowers SnS2 electrode shows low charge-transfer resistance, which contributes to the alloying reaction between metallic Sn and lithium ions (Li+) during charge/discharge cycles. Importantly, g-C3N4 nanosheets acting as a spacer can efficiently buffer the volume change and alleviate the collapse or aggregation of SnS2 electrode after repeated cycles.

Hierarchical porous carbon was synthesized from porphyra using nickel nanoparticles as the template for mesopore formation and as a catalyst for carbon graphitization. The porphyra-derived carbon (PDC) showed a high degree of graphitization (IG/ID = 4.17) and N-doping (5.32%). The reversible capacity of PDC was 1006.4 mAh/g at 0.1 A/g and 278.2 mAh/g at 5.0 A/g. Moreover, PDC demonstrated the reversible capacity of 520.8 mAh/g after 500 cycles at 1.0 A/g with 92.3% capacity retention rate. The PDC can be served as an advanced anode material for high-energy rechargeable lithium-ion batteries.

Tuning the coupling interface of a heterostructured catalyst is an effective approach to achieve abundant surface catalytic active sites and strong electronic interactions among active materials for improving electrocatalytic water splitting performance. Herein, we report a novel heterogeneous catalyst comprising Ni3S2 nanoparticles embedded in ultrathin NiV-layered double hydroxide nanosheet arrays supported on nickel foam, denoted as Ni3S2@NiV-LDH/NF. We demonstrate that the active edge-state length and the surface chemical state of such NiV-LDH-based heterostructures are well modulated by tailoring the coupling interfaces, resulting in the exposure of more catalytic reaction sites and enhancement of the electronic interactions between NiV-LDH and Ni3S2, thus greatly promoting the water dissociation kinetics. As expected, the optimized Ni3S2@NiV-LDH/NF heterostructures exhibit outstanding electrocatalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an extremely low overpotential of 126 mV and 190 mV to deliver 10 mA cm−2 for the HER and OER without iR compensation in alkaline media, respectively. More importantly, Ni3S2@NiV-LDH/NF simultaneously functioned as both the anode and cathode for water splitting to yield a current density of 10 mA cm−2 at a cell voltage of only 1.53 V with an outstanding durability for 160 h. This work provides a new insight into the regulation of the coupling interface for obtaining highly active heterostructured catalysts for overall water splitting.