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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.

Ti3C2Tx materials have large specific surface area, high in-layer conductivity, strong conductivity loss and good electromagnetic absorption properties. However, the impedance matching characteristics of Ti3C2Tx still need to be further optimized. Through cross-linking reaction, a poly-dopamine (PDA) protective layer is coated on the surface of Ti3C2Tx, and then, the N-doped pyrolytic carbon (N-PyC)/Ti3C2Tx hybrids are fabricated by heat treatment with the obtained PDA-Ti3C2Tx. The results show that Ti3C2Tx coated with N-PyC layered has a low degree of oxidation and a high dielectric loss, which is attributed to the carbon coating as a protective layer consumes Ti3C2Tx surface functional groups and reduces the O-terminals of Ti3C2Tx produced during the heat treatment process, thereby reducing oxidation. The high conductivity Ti3C2Tx is compounded with the medium loss material N-PyC, which can optimize the impedance matching characteristics. On the flip side defect polarization caused by N atoms in N-PyC is propitious to dissipate electromagnetic waves. Hence, N-PyC/Ti3C2Tx hybrids exhibit good electromagnetic wave absorption properties. When the mass ratio is 21wt% and the thickness is 2.6 mm, the minimum reflection coefficient of N-PyC/Ti3C2Tx is -26.5 dB in X-band.

The definition of the graph Fourier transform is a fundamental issue in graph signal processing. Conventional graph Fourier transform is defined through the eigenvectors of the graph Laplacian matrix, which minimize the $\ell_2$ norm signal variation. However, the computation of Laplacian eigenvectors is expensive when the graph is large. In this paper, we propose an alternative definition of graph Fourier transform based on the $\ell_1$ norm variation minimization. We obtain a necessary condition satisfied by the $\ell_1$ Fourier basis, and provide a fast greedy algorithm to approximate the $\ell_1$ Fourier basis. Numerical experiments show the effectiveness of the greedy algorithm. Moreover, the Fourier transform under the greedy basis demonstrates a similar rate of decay to that of Laplacian basis for simulated or real signals.

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 effectively improve the electrochemical performance of lithium-ion batteries through the design and manufacture of a new structure of composite electrode materials. Hence, in this work, we prepared a structure that Ge nanoparticles encapsulate in carbon spheres by a simple two-step method. When applied as an anode material for lithium-ion batteries, which serves a specific capacity of 529 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles with the Coulomb efficiency (CE) of over 99.8%. Otherwise, it also obtains preferable cycling stability and rate capability. Its prominent advantages in the electrochemical performance of Ge/C can be due to the synergy between carbon spheres and Ge nanoparticles: including highly electrical conductivity carbon spheres and the coated structure, which can reduce the volume change of Germanium nanoparticles. At the same time, we also provide a novel structure design method for those electrode materials that suffer from huge volume expansion in the course of charging and discharging to suppress their volume expansion, so that they can be better used or create more efficient and practical electrodes.

Layer-structured α-MoO3 with high theoretical capacity (1117 mAh g−1) is considered as one of the alternative anode materials for LIBs. However, the repeated insertion/extraction of Li+ often causes irregularly exfoliated layer structure of α-MoO3, especially the multiple-direction interlayer Li+ insertion/extraction shows rapid capacity decay. In this work, we achieve regularly exfoliated layer structure by inducing [100]-orientated plate-like α-MoO3 during high-temperature calcinations process. This regularly exfoliated layer structure is dominated by the optimized [100] single-direction Li+ interlayer diffusion way caused by the induced orientation growth. As anode for LIBs, the plate-like α-MoO3 exhibits capacity retention of 86.7% from 1st to 300th, showing enhanced stability of Li storage performance. This work indicates that inducing orientation growth of electrode material to optimize lithium-ion diffusion path can achieve regular exfoliation of layer structure, which can enhance the stability of Li storage performance. This conclusion can be used as a good reference for enhancing stability of layer-structured electrodes by structure design.

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.

In this work, the SnS2 nanoflakes electrode materials have been synthesized using citric acid as chelating agent for lithium-ions battery by a facile microwave hydrothermal method. Citric acid can form a strong ligand for metal ions, and the crystals growth is controlled by the interaction between ligand and hydrogen bond, which affects the nucleation, growth, and self-assembly in the synthesis process. Therefore, the SnS2 nanoflakes electrodes were obtained with the size and thickness of around 100–200 nm and ~ 30 nm, respectively. The SnS2 nanoflakes electrode delivers the initial discharge capacity of 1485.8 mAh g−1, the reversible capacity of 327.3 mAh g−1 at 100 mA g−1 after 100 cycles, and the Coulombic efficiency (CE) of about 99.8%. The prominent rate capability was exhibited for lithium-ion battery (387.5 mAh g−1 and 339.7 mAh g−1 at 800 and 1000 mA g−1, respectively). The outstanding electrochemical performance and high capacity retention rate mainly are ascribed to the fast charges, lithium-ions diffusion, and stable structure for SnS2 nanoflakes. This work could provide a potential approach to promote the electrochemical performances of sulfides electrode materials for lithium-ions battery.

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.

This paper investigates the limit cycles for planar differential system x˙=λx−y+Pn(x,y), y˙=x+λy+Qn(x,y), where Pn(x,y),Qn(x,y) are homogeneous polynomials of degree n. Using the method of upper an...

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 ...

Although emerging studies from high-income countries investigated the relationship between sedentary behavior (SB) and cardiovascular risk, little evidence came from developing countries. Moreover, the benefits of reallocating time from SB to physical activity (PA) on incident cardiovascular disease (CVD) are unknown. Using three cohorts from the Prediction for Atherosclerotic Cardiovascular Disease Risk in China project, we included 93 110 adults who were free from CVD at baseline. Cox proportional hazards models were used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for CVD, including stroke, coronary heart disease, and CVD death. Isotemporal substitution models were applied to estimate the per-hour effects of replacing SB with PA. After 5.8 years follow-up, 3799 CVD cases were identified. A gradient positive association between sedentary time and incident CVD was observed. Relative to those with

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.

This paper is devoted to the investigation of generalized Abel equation x ˙ = S ( x , t ) = ∑ i = 0 m a i ( t ) x i , where a i ∈ C ∞ ( [ 0 , 1 ] ) . A solution x ( t ) is called a periodic solution if x ( 0 ) = x ( 1 ) . In order to estimate the number of isolated periodic solutions of the equation, we propose a hypothesis (H) which is only concerned with S ( x , t ) on m straight lines: There exist m real numbers λ 1 ⋯ λ m such that either ( − 1 ) i ⋅ S ( λ i , t ) ≥ 0 for i = 1 , ⋯ , m , or ( − 1 ) i ⋅ S ( λ i , t ) ≤ 0 for i = 1 , ⋯ , m . By means of Lagrange interpolation formula, we prove that the equation has at most m isolated periodic solutions (counted with multiplicities) if hypothesis (H) holds, and the upper bound is sharp. Furthermore, this conclusion is also valid under some weaker geometric hypotheses. Applying our main result for the trigonometrical generalized Abel equation with coefficients of degree one, we give a criterion to obtain the upper bound for the number of isolated periodic solutions. This criterion is “almost equivalent” to hypothesis (H) and can be much more effectively checked.

CuAlO2, with a relative higher conductivity than other ceramics, is a potential candidate in microwave absorption fields. Herein, to enhance the wide-range efficient microwave absorption property of CuAlO2 powders, Fe-doped CuAlO2 powders were synthesized via a facile sol–gel method. The X-ray diffraction results displayed that 5 at.% Fe doping CuAlO2 powders maintained the original delafossite structure and excessive Fe doping could destroy the structure of CuAlO2. When the Fe doping content increased to 20 at.%, FeAl2O4 phase formed. The Fe doping had significant effects on the electromagnetic parameters of samples. Compared with pure CuAlO2, the Fe-doped CuAlO2 powders have a higher e″ and µ″, which is beneficial to improve the electromagnetic absorption property. The calculated reflection loss curves demonstrated that the sample with at.% Fe doping displayed the most excellent microwave absorption property in thickness of 3.93 mm, showing a minimum reflection loss of − 20.5 dB at the frequency of 9.86 GHz and reflection loss below − 10 dB in the whole measured frequency. Compared with other potential high temperature microwave absorption materials, Fe-doped CuAlO2 powders exhibit a wide-range microwave absorption property.

The photocatalytic reclamation of the environment requires improved catalysts, as severe charge recombination currently limits their practical application. This study describes a simple synthesis of SnO2−x/Sb2O3 composite by the mechanical milling method. The coupling of SnO2−x possessing oxygen vacancies (OVs) with Sb2O3 is a new approach for obtaining materials with outstanding photocatalytic properties. For the photo-oxidation of isopropanol (IPA) within 5 h, the acetone yield over SnO2−x/Sb2O3 composite with mass ratio of 1:4 was 22.67 and 10.5 times higher than those of SnO2−x and Sb2O3, respectively, and the carbon dioxide output was 13.29 and 7.46 times higher than those of SnO2−x and Sb2O3, respectively. This results showed that the OVs-induced SnO2−x/Sb2O3 heterostructures have a very high IPA photo-oxidation catalytic degradation activity, even after six cycles with no obvious decline. Combination of defect engineering and heterojunction can be a powerful tool for obtaining broad light absorption and high photo-induced charge separation efficiency, which contributes to improving the photocatalytic IPA degradation property.

Most of the biomedical materials printed using 3D bioprinting are static and are unable to alter/transform with dynamic changes in the internal environment of the body. The emergence of four-dimensional (4D) printing addresses this problem. By preprogramming dynamic polymer materials and their nanocomposites, 4D printing is able to produce the desired shapes or transform functions under specific conditions or stimuli to better adapt to the surrounding environment. In this review, the current and potential applications of 4D-printed materials are introduced in different aspects of the biomedical field, e.g., tissue engineering, drug delivery, and sensors. In addition, the existing limitations and possible solutions are discussed. Finally, the current limitations of 4D-printed materials along with their future perspective are presented to provide a basis for future research.

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.

Although emerging researches have linked ambient fine particulate matter (PM(2.5)) to obesity, evidence from high-polluted regions is still lacking. We thus assessed the long-term impacts of PM(2.5) on body mass index (BMI) and the risk of the prevalence of overweight/obesity (BMI≥25 kg/m(2)), by incorporating the well-established Prediction for Atherosclerotic Cardiovascular Disease Risk in China (China-PAR) project comprising 77,609 participants with satellite-based PM(2.5) estimates at 1-km spatial resolution. The average of long-term PM(2.5) level was 70.4 μg/m(3), with the range of 32.1–94.2 μg/m(3). Each 10 μg/m(3) increment of PM(2.5) was associated with 0.421 kg/m(2) (95% confidence interval [CI]: 0.402, 0.439) and 13.5% (95% CI: 12.8%, 14.3%) increased BMI and overweight/obesity risk, respectively. Moreover, compared with the lowest quartile of PM(2.5) (≤57.5 μg/m(3)), the relative risk of the prevalence of overweight/obesity from the highest quartile (>85.9 μg/m(3)) was 1.611 (95% CI: 1.566, 1.657). The exposure-response curve suggested a non-linear relationship between PM(2.5) exposure and overweight/obesity. Besides, the association was modified by age, diabetes mellitus, hypertension and dyslipidemia status. Our study provides the evidence for the adverse impacts of long-term PM(2.5) on BMI and overweight/obesity in China, and the findings are important for policy development on air quality, especially in severely polluted areas.

In this work, a highly photocatalytic Ag/In2S3 was synthesized via the hydrothermal and photoreduction method. The as-prepared photocatalysts were confirmed by XRD, SEM, HRTEM, and XPS showing that Ag nanoparticles were decorated on the In2S3 surface. Photocatalytic activities of photocatalysts were investigated for photodegradation of methyl orange (MO) under visible light. The Ag/In2S3 composites showed the enhanced photocatalytic efficiency of 97% under visible light irradiation for 90 min, which was about 3.0 times higher than that of pure In2S3. The enhanced photocatalytic performance could be owing to the SPR of Ag and the Schottky junction formed between Ag and In2S3. Our PL results indicate the inhibited recombination of the photogenerated electron–hole pairs in In2S3 upon the attachment of Ag nanoparticles. The active species tests demonstrate that the superoxide radical (·O2−) and h+ are responsible for the efficient degradation of MO over Ag/In2S3. In addition, it also proposes a potential mechanism for enhancing the photocatalytic activity.

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.

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.

The risk of incident hypertension associated with long-term exposure to fine particulate matter (PM 2.5 ) was still unclear by studies conducted in North America and Europe, and this relationship has rarely been quantified at higher ambient concentrations typically found in developing countries. We aimed to investigate the association between PM 2.5 and incident hypertension using the large-scale prospective cohorts in China. We included 59 456 participants without hypertension aged ≥18 years from the China-PAR (Prediction for Atherosclerotic Cardiovascular Disease Risk in China) project. Data on ambient PM 2.5 at participants’ residential address were obtained during 2004 to 2015 using a satellite-based spatial-temporal model. Hazard ratios and 95% CIs were calculated for incident hypertension using stratified Cox proportional hazards models with adjustment of potential confounders. The findings indicated that average PM 2.5 concentration from 2004 to 2015 at study participants’ address was 77.7 μg/m 3 . During the follow-up of 364 947 person-years, we identified 13 981 incident hypertension cases. Compared with the lowest quartile exposure of PM 2.5 , participants in the highest quartile had an increased risk of incident hypertension with a hazard ratio (95% CI) of 1.77 (1.56–2.00). Each 10 μg/m 3 increment of PM 2.5 concentration could increase 11% risk of hypertension (hazard ratio, 1.11; 95% CI, 1.05–1.17). This cohort study provided the first evidence from China that long-term exposure to PM 2.5 was independently associated with incident hypertension at relatively high ambient concentrations. Stringent strategies on PM 2.5 pollution control are warranted to improve the air quality and contribute to the reduction of disease burden of hypertension in China.

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.