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Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries (LIBs) for large-scale energy storage considering the abundance and low cost of Na-containing resources. However, the energy density of SIBs has been limited by the typically low specific capacities of traditional intercalation-based cathodes. Metal fluorides, in contrast, can deliver much higher capacities based on multi-electron conversion reactions. Among metal fluorides, CuF2 presents a theoretical specific capacity as high as 528 mAh/g while its Na-ion storage mechanism has been rarely reported. Here, we report CuF2 as a SIB cathode, which delivers a high capacity of 502 mAh/g but suffers from poor electrochemical reversibility. As a solution, we adjust the cell configuration by inserting a carbon-coated separator, which hinders the transportation of dissolved Cu ions and improves the reversibility of the CuF2 cathode. By using in-situ XRD measurements and theoretical calculation, we propose that a one-step conversion reaction occurs during the discharge process, and a reconversion reaction competes with the oxidization of Cu to dissolved Cu ion during the charge process.

Flexible strain sensors have received increasing attention with the development of wearable electronic devices. However, integrating wide strain detection range, high sensitivity while maintaining relatively wide linear response range for such sensor system still remain a challenge. A fabric based flexible sensor (S-CNT/PDMS-F) was designed and fabricated, and the sensor can simultaneously achieve high sensitivity, wide linear response and strain detection range by combining self-segregated carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composites and elastic medical bandage. It has been observed that this new sensor system can achieve a high sensitivity with a gauge factor of 615, a large linear responsive range of 0–100% strain (R2 ​= ​0.993) and a wide strain detection range of ∼ 200%, which is superior to almost all the reported CNT/PDMS flexible strain sensors. Compared to the similar fabric based strain sensor system deploying non self-segregated structure (C-CNT/PDMS-F), our S-CNT/PDMS-F demonstrates higher electrical conductivity and lower electrical percolation threshold and response time of 55 ​ms, as well as more stable and repeatable performance under cyclic loading conditions. The capability of the sensors in monitoring physiological activities and weight distribution has also been demonstrated.

In the present work, a phase-field model was developed to investigate the influence of recrystallization on bubble evolution during irradiation. Considering the interaction between bubbles and grain boundary (GB), a set of modified Cahn-Hilliard and Allen-Cahn equations, with field variables and order parameters evolving in space and time, was used in this model. Both the kinetics of recrystallization characterized in experiments and point defects generated during cascade were incorporated in the model. The bubble evolution in recrystallized polycrystalline of U–Mo alloy was also investigated. The simulation results showed that GB with a large area fraction generated by recrystallization accelerates the formation and growth of bubbles. With the formation of new grains, gas atoms are swept and collected by GBs. The simulation results of bubble size and distribution are consistent with the experimental results.

A Microfiber Mach-Zehnder interferometer (MMZI) based on tapered seven-core fiber (SCF) for curvature measurement has been reported and demonstrated. The tapered SCF promoted the light coupling efficiency from the single-mode fiber (SMF) to the SCF, which results in the transmission spectrum with a low loss and high extinction ratio. In the process of curvature measurement, the sensitivity can reach up to 174.02957 nm/m−1, which is the highest curvature sensitivity in the MZI with SCF as best as we have known. Furthermore, the maximum temperature sensitivity is 0.00956 nm/°C when the temperature changes from 30 °C to 140 °C. It shows that this sensor is naturally insensitive to temperature, which has a good performance in avoiding the cross-sensitivity effect between the temperature and curvature.

In this work, we developed the first 3D-printed polyetheretherketone (PEEK)-based bone scaffold with multi-functions targeting challenging bone diseases such as osteosarcoma and osteomyelitis. A 3D-printed PEEK/graphene nanocomposite scaffold was deposited with a drug-laden (antibiotics and/or anti-cancer drugs) hydroxyapatite coating. The graphene nanosheets within the scaffold served as effective photothermal agents that endowed the scaffold with on-demand photothermal conversion function under near-infrared laser irradiation. The bioactive hydroxyapatite coating significantly boosted the stem cell proliferation in vitro and promoted new bone growth in vivo. The presence of antibiotics and anti-cancer drugs enabled eradication of drug-resistant bacteria and ablation of osteosarcoma cancer cells, the treatment efficacy of which can be further enhanced by on-demand laser-induced heating. The promising results demonstrate the strong potential of our multi-functional scaffold in applications such as bone defect repair and multimodal treatment of osteosarcoma and osteomyelitis.

Single-crystalline LiNi0.6Co0.2Mn0.2O2 cathodes have received great attention due to their high discharge capacity and better electrochemical performance. However, the single-crystal materials are suffering from severe lattice distortion and electrode/electrolyte interface side reactions when cycling at high voltage. Herein, a unique single-crystal LiNi0.6Co0.2Mn0.2O2 with Al and Zr doping in the bulk and a self-formed coating layer of Li2ZrO3 in the surface has been constructed by a facile strategy. The optimized cathode material exhibits excellent structural stability and cycling performance at room/elevated temperatures after long-term cycling. Specifically, even after 100 cycles (1C, 3.0-4.4 V) at 50 °C, the capacity retention for the Al and Zr co-doped sample reaches 92.1%, which is much higher than those of the single Al-doped (85.4%), single Zr-doped (87.1%), and bare samples (76.3%). The characterization results and first-principles calculations reveal that the excellent electrochemical properties are attributed to the stable structure and interface, in which the Al and Zr co-doping hinders cation mixing and suppresses detrimental phase transformations to reduce internal stress and mitigate microcracks, and the coating layer of Li2ZrO3 can protect the surface and suppress interfacial parasitic reactions. Overall, this work provides important insights into how to simultaneously build a stable bulk structure and interface for the single-crystal NCM cathode via a facile preparation process.

Aqueous Zn‐ion batteries (AZIBs) are regarded as a promising alternative to the widely used lithium‐ion batteries in large‐scale energy storage systems. The researches on the development of novel aqueous electrolyte to improve battery performance have also attracted great interest since the electrolyte is a key component for Zn2+ migration between cathode and anode. Herein, we briefly summarized and illuminated the recent development tendency of aqueous electrolyte for AZIBs, then deeply analyzed its existing issues (water decomposition, cathode dissolution, corrosion and passivation, and dendrite growth) and discussed the corresponding optimization strategies (pH regulation, concentrated salt solution, electrolyte composition design, and functional additives). The internal mechanisms of these strategies were further revealed and the relationships between issues and solutions were clarified, which could guide the future development of aqueous electrolytes for AZIBs.

The pure and Yb-doped 3D ordered porous SnO2 with a controllable pore diameter (around 50 nm, 800 nm, and 1200 nm) were prepared by a simple template method. 3 at% Yb-doped 51.3 nm ordered porous SnO2 (51.3 nm SnO2/3%Yb) showed the largest specific surface area (70.08 m2/g) and the biggest oxygen vacancy in nitrogen adsorption–desorption and XPS analysis. The response of 51.3 nm SnO2/3%Yb is 95 against 50 ppm HCHO at 108 °C, which is 3.7 times higher than 1228.0 nm SnO2/3%Yb (27), 2.1 times higher than 806.0 nm SnO2/3%Yb (45), and 2.4 times higher pure 57.3 nm SnO2(40). However, the response of pure 57.3 nm SnO2 (40) is only 2.9 times higher than pure 1231.0 nm SnO2(13.5), and 1.2 times higher than pure 832.1.0 nm SnO2 (30). Especially, the detectable formaldehyde (HCHO) of 51.3 nm SnO2/3%Yb minimum limit has been reduced to 50 ppb and the relevant response is 3.5. Besides, 51.3 nm SnO2/3%Yb also exhibited high linearity (50 ppb-200 ppm), the fast response time (2 s) and excellent selectivity toward HCHO. Above all, for the same kinds of SnO2 nanomaterials, the smaller pore size is, the stronger sensitivity it will be, and under the effect of Yb doping, the gas sensitivity is enhanced more significantly with the decrease of the pore size. Besides, for the same kinds of SnO2 nanomaterials that have the same pore size, the gas-sensitive property is also significantly enhanced due to the doping of Yb.

Developing high-efficiency, inexpensive, and steady non-precious metal oxygen reduction reaction (ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery. Here, we have prepared the Cu/Cu2O-NC catalyst with excellent ORR performance and high stability, due to the synergistic effect of Cu and Cu2O nanoparticles. The half-wave potential (0.8 V) and the limiting-current density (5.20 mA/cm2) of the Cu/Cu2O-NC are very close to those of the 20% Pt/C catalyst (0.82 V, 5.10 mA/cm2). Besides, it exhibits excellent performance with a maximal power density of 250 mW/cm2 and a stable continuous discharge for more than 90 h in the Al-air battery test. The promoting effects of Cu2O towards Cu-based ORR catalysts are illustrated as follows: (i) Cu2O is the major ORR active site by the redox of Cu(II)/Cu(I), which provides excellent ORR activities; (ii) Cu can stabilize the location of Cu2O by assisting the electron transfer to Cu(II)/Cu(I) redox, which is conducive to the high stability of the catalyst. This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.

Density functional theory calculations were used to study the effects of inherent impurities C, N, and O on the stability and the self-trapping of interstitial He atoms in body-centered-cubic vanad...

Phase transition engineering, with the ability to alter the electronic structure and physicochemical properties of materials, has been widely used to achieve the thermodynamically unstable metallic...

Severe zinc dendrite growth is a formidable challenge in aqueous zinc-ion batteries during repeated cycles because of the uneven distribution of electric fields on a post-stripping zinc anode. Herein, we demonstrate a totally new nucleation mechanism by introducing cations with high valence (Ce3+ and La3+) into the electrolyte to homogenize electric fields and regulate the zinc deposition behavior. Intriguingly, a detailed evolution investigation of surface morphology discloses that zinc nucleation shifts to progressive nucleation via the preferential adsorption of cation additives from instantaneous nucleation in the addtive-free electrolyte, thereby resulting in the stable zinc stripping/plating behavior. A symmetric cell with 0.01 M Ce2(SO4)3 can be cycled at 5 A g−1 with a lower voltage hysteresis of 83.3 mV for more than 700 h, which is remarkably longer than that of the pristine one (282 h). A higher capacity retention of Zn//NaV3O8·1.5H2O cell (87.0%) after 250 cycles at 5 A g−1 is also achieved in comparison with that in addtive-free electrolyte (68.1%). This work provides new and deep insights into the effects of cation adsorption on zinc nucleation.

A microfiber Mach-Zehnder interferometer (MMZI) with two spindle-shaped structures was reported for measuring temperature and curvature. Due to the core-separated structure, the MMZI could excite more high-order modes, which improves the sensitivity more efficiently. When the central waist region is 4 μm, the sensitivities for temperature and curvature were 1290.4pm /°C and 56.1947 nm/m−1, respectively. Furthermore, the sensitivity could be improved effectively by increasing the length of the central waist region. Increasing the length of central waist region to 6 μm, the temperature sensitivity of the sensor could up to 1756.3 pm/°C, which was the highest temperature sensitivity we have known in MMZI.

The glass transition and dynamics of densely grafted semiflexible polymer brushes are studied by molecular dynamics simulation. The glass transition temperature (Tg) increases with the polymer rigidity. The local glass transition temperature (Tg,local) is estimated from the temperature-dependent dynamics of individual segments including the lateral position fluctuation and lateral mean square displacement. Different from the flexible polymer brush, Tg,local of semiflexible polymer brushes is roughly independent of the segment height. Our simulation reveals that the glass transition is in synchronism with an abrupt change of the chain conformation in semiflexible polymer brushes. When the temperature drops to near Tg, the semiflexible polymer chains elongate, tilt, and become more ordered. Moreover, enhanced segmental dynamics is observed at temperatures just above Tg for the semiflexible polymer brushes.

It is crucial to develop high-performance and cost-effective bifunctional electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) toward overall water splitting. Herein, a unique heterostructure of reduced graphene oxide (rGO) and CoNiO2 nanosheets directly grown on nickel foam (NF) were successfully fabricated and applied as a kind of highly efficient bifunctional electrocatalyst. The optimum CoNiO2@rGO/NF electrode exhibits excellent electrocatalytic OER performance with an overpotential of only 272 mV to drive a current density of 100 mA·cm−2, and HER performance with an overpotential of 126 mV to achieve a current density of 10 mA·cm−2. Meanwhile, the electrodes also display outstanding long-term stability for OER and HER with negligible activity and morphology degradation after at least 40 h testing. Furthermore, when employed as both cathode and anode for overall water splitting, CoNiO2@rGO/NF electrode only requires 1.56 V at 10 mA·cm−2 and operates stably for over 40 h, which is among the best performing Co-based and Ni-based non-precious metal electrocatalysts. Detailed characterizations reveal that the extraordinary electrocatalytic performance should be attributed to the synergistic effect of the unique heterostructure of CoNiO2 nanosheets and rGO for increasing the electrode conductivity and integrity, ultrasmall primary particle size for providing larger electrode/electrolyte contact area and abundant active sites, and three-dimensional (3D) conductive networks for facilitating the electrochemical reaction.

Aluminum–air (Al–air) batteries are promising candidates for energy storage applications because of their high theoretical energy density and low cost. Nevertheless, their developments have been severely hindered by multiple obstacles, among which the activation and self-corrosion inhibition of Al anode have been considered to be significant challenges. In neutral electrolytes, the main problem is the activation of Al anode, while the self-corrosion of Al anode becomes dominant in alkaline electrolytes. Considerable efforts have been devoted to overcoming the dilemma associated with the Al anode. This review firstly underscores the underlying mechanisms of passivation and self-corrosion of Al anode in different electrolytes. Then, specific attentions are paid to Al alloy anode, including the role of various elements and standard processing technology. Finally, general conclusions, current limitations, and future perspectives on Al alloy anode are presented.

The structure and surface properties of the sensing materials have been considered as the main factors for the fabrication of metal–oxide semiconductor gas sensors. In this paper, a one-step hydrothermal method for the preparation and control of the morphology of α-Fe2O3 is reported. The results show that the amount of glycol has a great influence on the morphology of the products. With the variation in ethylene glycol concentration (from 30 to 110 ml), we can obviously see the product was assembled into three-dimensional porous α-Fe2O3 micro-flower structure from two-dimensional nanochips from scanning electron microscope (SEM) pictures. When the ethylene glycol was 70 ml, the micro-flower structure was the most uniform and perfect. It additionally showed the largest specific surface area (63.69 m2/g) and the biggest oxygen vacancy in nitrogen adsorption–desorption and XPS analysis. Further gas sensitivity test showed that gas sensitivity was also the best. Under the low operating temperature (210 °C), the porous α-Fe2O3 micro-flower (70 ml glycol) showed the highest response (49.4) to 100 ppm acetone, the sensitivity of other materials was 8.2/30 ml, 14.7/40 ml, 38.4/50 ml, 36.7/90 ml, 10.3/100 ml, 4.8/110 ml, respectively. In addition, the porous α-Fe2O3 micro-flower (70 ml glycol) has excellent selectivity, short response/recovery time (1 s/31 s), low detection offline (2.2 to 0.2 ppm acetone), and good stability. The reason for the improvement of gas-sensing performance is mainly due to the change of morphology, decrease of crystallite size, the increase of oxygen vacancy, and specific surface area.

Alkaline aluminum-air batteries show great potential for energy storage applications because of their high theoretical energy density and low cost. However, they are suffering from severe anodic self-corrosion and the gelation of electrolyte which greatly reduce the practical energy density and shelf life. Herein, we firstly construct an efficient high-energy alkaline Al-air battery based on high-concentration potassium acetate-potassium hydroxide electrolyte and prototype optimization. The self-corrosion of Al anode is greatly suppressed owing to the special hydrate structure in such electrolyte. The Al-air battery with optimum electrolyte demonstrates remarkable increased discharge capacity of 2324 mAh g−1, and the constructed miniaturized Al-air battery enables an outstanding system energy density of 436.1 ​Wh kg−1 (compared with 85.8 ​Wh kg−1 of normal electrolyte) after integrating a discharge product removing system. This work opens up a new direction for the practical realization of high-energy, low-cost, and high-efficiency alkaline Al-air battery and other aqueous metal-air batteries.

Carbon fiber reinforced polymer composites are widely used in aircraft structures due to their excellent mechanical properties, light weight, and corrosion resistance compared to conventional metal...

Helium (He) trapping at carbide precipitates is significant for understanding the macroscopic effects of He in the normal reduced activation ferritic/martensitic (RAFM) steels and castable nanostructured alloys (CNAs) under irradiation. In this study, the behavior of intrinsic point defects and He impurities in VC is investigated by first-principles calculations. The formation of carbon (C) vacancy is quite easy and vacancy makes covalent interaction of neighboring C and V atoms more obvious. Besides, the diffusion of vacancy in VC is significantly slower than that in Fe matrix. It's worth noting that the interaction between carbon vacancies is repulsive which means that the formation of large voids maybe difficult in VC. Apart from vacancy, He impurities are also investigated. Interstitial He is less stable and diffuses more easily inside VC precipitate than inside TaC and Fe matrix. Besides, vacancy can trap much more He in VC than in Fe matrix. The result means that vacancy-abundant VC particle may have stronger ability to trap He than Fe matrix. Due to the repulsion of vacancies, we suggest that the formation of large He bubbles in VC is difficult. That is to say, little He bubbles have a dispersive distribution in VC. These theoretical results can help to understand the behavior of vacancy and He impurities in VC precipitate and further the bubble formation at precipitate in normal RAFM steels and CNAs.

Aqueous zinc‐ion batteries (ZIBs) have been intensively investigated as potential energy storage devices on account of their low cost, environmental benignity, and intrinsically safe merits. With the exploitation of high‐performance cathode materials, electrolyte systems, and in‐depth mechanism investigation, the electrochemical performances of ZIBs have been greatly enhanced. However, there are still some challenges that need to be overcome before its commercialization. Among them, the obstinate dendrites, corrosion, and hydrogen evolution reaction (HER) on Zn anodes are critical issues that severely limit the practical applications of ZIBs. To address these issues, various strategies have been proposed, and tremendous progress has been achieved in the past few years. In this article, we analyze the origins and effects of the dendrites, corrosion, and HER on Zn anodes in neutral and mildly acid aqueous solutions at first. And then, a scientific understanding of the fundamental design principles and strategies to suppress these problems are emphasized. Apart from these, this article also puts forward some requirements for the practical applications of Zn anodes as well as several cost‐effective‐modifying strategies. Finally, perspectives on the future development of Zn anodes in aqueous solutions are also briefly anticipated. This article provides pertinent insights into the challenges on anodes for the development of high‐performance ZIBs, which will greatly contribute to their practical applications.

How to improve the intrinsic activity of the Pt catalysts is still a pivotal issue in direct methanol fuel cells. Here, we prepared ultrathin Pt-M (M = Fe, Co, Ni) bimetallic networked nanowire usi...

Lithium–oxygen batteries have received much research attention, and the issue of high overpotential of lithium–oxygen batteries is pivotal to be resolved. Developing efficient electrocatalysts is c...

3D porous SnO2 nanomaterials enhanced gas sensitivity properties for formaldehyde has been successfully prepared by a simple template method. The morphology of the synthesized SnO2 was observed by a scanning electron microscope (SEM) as a 3D porous structure with a pore diameter of 120 nm. We systematically studied the gas sensing performance of 3D porous SnO2 and particulate SnO2. The result shows that the response value of 3D porous SnO2 to 100 ppm formaldehyde gas was 51.0 at low temperature 230 ℃, which was 6.4 times higher than that of particulate SnO2 (8.0), and the response/the recovery time of 3D porous SnO2 was 8 s/15 s. The minimum detection concentration of 3D porous SnO2 was 0.5 ppm formaldehyde with the response value of 2. However, particulate SnO2 can only be detected 10 ppm with the response value of 2. In addition, the selectivity coefficient of 3D porous SnO2 for formaldehyde was up to 7, which is better than particulate SnO2 (1). The reason for the enhanced sensitivity of 3D porous SnO2 formaldehyde gas is not only related to its porous structure and smaller grain size, but also to the increase in oxygen vacancies.

In this study, we present six structural models for amorphous Ga2O3 (a-Ga2O3) with different mass densities from ab initio molecular dynamics simulations. The detailed local structural order, non-perfect coordination number, electronic and vibrational properties of a-Ga2O3 as well as the energetics and stability of O vacancy with various charge states have been systemically investigated. As the density increases, the first peak in the radial distribution function is weakened and the range of vibrational frequencies is narrowed, while the average coordination number and band gap gradually increase. Density also plays an important role in oxygen vacancy formation in a-Ga2O3. In the low-density a-Ga2O3, oxygen vacancy is more stable and the average formation energy of oxygen vacancy (VO) with neutral state is 3.32–3.70 eV lower than that in crystalline β-Ga2O3 (4.20 eV). In the high-density a-Ga2O3, VO in the 2 + charge state may form spontaneously in the case of lower Fermi energy and the thermodynamic transition energy for VO was found to shift to higher Fermi energy. Hence, the electron trap levels observed in experiment might be correlated with local structural distortion and non-perfect coordination number. Moreover, highly localized valence tail has been observed in all the six a-Ga2O3 systems. Thus, it would be hard to shift the Fermi level to the valence band, leading to rarely observed p-type conductivity in amorphous Ga2O3. These results not only establish a fundamental picture on the origin of a wide range of defect levels in Ga2O3 thin films deposited under different conditions, but also provide useful evidence to identify them with oxygen vacancy states.

In this study, the chitosan‐based release microspheres were prepared by spray drying method. Chitosan was used as the carrier material, and Panax notoginseng extract, Codonopsis extract, and Atractylodes extract (the mass ratio was 2:7:5) were active substance. The spray drying preparation process of microsphere was optimized by single factor experiment and L9 (34) orthogonal design. Drug loading (DL), particle size, and sustained release performance of microspheres were investigated. The mass fraction of chitosan was 1.5%, the mass ratio of drug to chitosan was 1:3, the inlet air temperature was 130°C, and the injection rate was 400 ml/hr. The chitosan‐based microspheres prepared under the above conditions had a smooth surface, and the DL was 23.87 ± 0.93%; the average particle diameter was 10.27 ± 1.05 μm, and the encapsulation efficiency (EE) of the microspheres was 91.28 ± 1.04%. The preparation process of chitosan‐based drug microsphere prepared by spray drying method was simple and stable. The prepared microspheres in this paper showed a sustained release effect in vitro., To study the characteristics and the drug release of the chitosan‐based microspheres in vitro. The gastric mucosal protective drug microspheres were used chitosan as the carrier material and prepared with Panax notoginseng extract, Codonopsis extract, and Atractylodes extract by spray drying. The preparation process of chitosan‐based gastric mucosa protective drug microsphere was simple and stable.

Surface modification is an important element of textile manufacturing. The SiO2/Ag sol–gel was coated on the cotton/linen fabric by a simple two-dipping-two-rolling coating machine. SEM, Zeta-potential, (ATR)-FTIR and XRD, physical properties, water-droplet adsorption, antibacterial performance and water-resisting property have been adopted as the characterization techniques. The Zeta-potential showed that the nano-Ag particles affected the size of SiO2 nanoparticles. The results showed that antibacterial activity and hydrophobic property of cotton/linen fabric increased with the increasing concentration of the AgNO3. Air permeability was not decreased considerably, whereas tensile strength was increased significantly after coating twice. The SiO2/Ag coating cotton/linen fabric had an excellent antibacterial performance. Our results demonstrate that this SiO2/Ag coated cotton/linen fabric is a step towards better hydrophobic performance of textile materials.

Sodium superionic conductor structured Na3V2(PO4)2F3 is demonstrated to be a promising cathode material for sodium-ion batteries (SIBs) due to its high operating potential and robust 3D open framework for fast Na+ migration, but suffers from intrinsic low electronic conductivity caused by the insulating [PO4] tetrahedra. Herein, Na3V2(PO4)2F3@rGO (NVPF@rGO) microcuboids with different exposed crystal facets are fabricated via guiding the crystal growth orientation with the existence of NaX (X = F, Cl, Br). When employed as a cathode for SIBs, the optimum NVPF@rGO electrode exhibits a high discharge capacity of 127.5 mA h g−1 at 0.2C (1C = 128 mA g−1) and impressive rate performance of 73.7 mA h g−1 even at a high rate of 50C. Further testing of the commercial soft carbon//NVPF@rGO full cell delivers relatively excellent electrochemical properties in terms of an average operating voltage of ∼3.3 V, decent cycling stability at 5C (74.5% of the initial capacity after 500 cycles), and high energy density of 338 W h kg−1 (calculated by the mass of the NVPF cathode). Kinetic analysis results reveal that the ameliorated electrochemical properties should be related to the significantly enhanced ion migration at the material/electrolyte interface endowed by the oriented crystal growth along the [110] direction. This work will provide a novel approach for constructing advanced cathode materials for SIBs.

The dynamical and conformational properties of polymer chains are affected significantly by strongly attractive nanoparticles. The adsorption of polymer chains on nanoparticles not only reduces the dynamics but also changes the conformation of polymer chains. For orderly distributed nanoparticles of size roughly the same as the radius of gyration of polymer chains, the variation of the diffusivity is highly related to that of the statistical size and can be explained mainly from the adsorption of polymers. In particular, both the polymer's size and diffusivity reach the minimum when the number of polymer chains matches the number of nanoparticles where polymer chains are mostly adsorbed on separate nanoparticles. The behavior of diffusivity can be explained from the cooperation of polymer adsorption and nanoparticle-exchange motion. Adsorption of the polymer chain slows down the diffusion, whereas the nanoparticle-exchange motion accelerates the diffusion of polymer chains.

Na-ion batteries (SIBs) have garnered tremendous interest due to their unique advantages of high safety, abundant Na resources, and low cost. Great research efforts of SIBs have been devoted to the exploitation and in-depth mechanism investigation of high-performance electrode materials. Among the various cathodes, Na3V2(PO4)2F3 (NVPF), a representative member of Na superionic conductor (NASICON) structured compounds, has been considered to be a promising candidate because of its superior structural stability, fast ion transport, high operating potential and so on. However, its electrochemical performance and future large-scale applications have been hindered by the relatively low electronic conductivity and high cost of NVPF. This review emphasizes the crystal structure and Na storage mechanisms together with synthetic methods of NVPF, and then summarizes various proposed strategies including carbon coating, element doping, size and morphology design, etc. to meliorate the electrochemical performance of NVPF. Additionally, the applications of the NVPF cathode in other battery systems are included. Finally, our perspectives on the subsequent research and optimization of NVPF are also shared. This review not only is a comprehensive summary of NVPF for the first time but also provides a good reference for the rational design of high-performance NVPF in the future.

Sodium ion batteries have emerged as a potential low-cost candidate for energy storage systems due to the earth abundance and availability of Na resource. With the exploitation of high-performance electrode materials and in-depth mechanism investigation, the electrochemical properties of sodium ion batteries have been greatly improved. However, there are still various challenges need to be overcome before its commercial application. Among them, the low initial Coulombic efficiency of high-capacity anode is a critical issue that seriously limits the practical energy density of sodium ion full battery. This review firstly highlights the underlying mechanisms of the low initial Coulombic efficiency, such as the formation of SEI film from the decomposition of electrolyte, poor reversibility of sodiation/desodiation process, etc., and then summarizes the emerging strategies including electrolyte optimization, structure/morphology design, surface engineering, binder optimization and so on, to overcome them. Finally, some Na compensation strategies like pre-sodiated anode, sacrificial additives and sodium-rich cathode for practical application are discussed. This review provides pertinent insights into the challenges of initial Coulombic efficiency for the development of high energy sodium ion battery, which will benefit to its practical application.

Polyaniline, polyaniline/graphene composites were synthesized by a novel in situ chemical oxidative polymerization method including two oxidants. The morphology and structure of the material were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The electrochemical performance of polyaniline (PANI)-based composites was tested by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) testing, and constant current charge and discharge (GCD) tests. At 0.2 C of constant current, the discharge specific capacities of PANI/graphene oxide (PANI/GO) and PANI/GO-sodium borohydride (graphene oxide is reduced by sodium borohydride, named PANI/GO-NaBH4) were as high as 183 mAh/g and 192 mAh/g, respectively, which was nearly twice as high as that of PANI (100 mAh/g). After 100 charge and discharge cycles, the capacity retention rates of PANI, PANI/GO, and PANI/GO-NaBH4 were 80.4%, 89.4%, and 95.05%, respectively; the cycle performance was greatly improved before the modification. These results indicate that the composite has exciting potentials for the cathode material of zinc-rechargeable battery.

In this work, we developed the first 3D PEEK based bone scaffold with multi-functions targeting challenging bone diseases such as osteosarcoma and osteomyelitis. 3D printed PEEK/graphene nanocomposite scaffold was deposited with drug laden (antibiotics and/or anti-cancer drugs) hydroxyapatite coating. The graphene nanosheets within the scaffold served as effective photothermal agents that endowed the scaffold with on-demand photothermal conversion function under NIR laser irradiation. The bioactive hydroxyapatite coating significantly boosted the stem cell proliferation in vitro and promoted the new bone growth in vivo. The presence of antibiotics and anti-cancer drugs enabled eradication of drug resistant bacteria as well as ablation of osteosarcoma cancer cells, the treatment efficacy of which can be further enhanced by the on-demand laser induced heating. The promising results demonstrate the strong potential of our multi-functional scaffold in applications such as bone defect repair as well as multimodal treatment of osteosarcoma and osteomyelitis.

Integrating sulfur cathodes with effective catalysts to accelerate polysulfide conversion is a suitable way for overcoming the serious shuttling and sluggish conversion of polysulfides in lithium-sulfur batteries. However, because of the sharp differences in the redox reaction kinetics and complicated phase transformation of sulfur, a single-component catalyst cannot consistently accelerate the entire redox process. Herein, hierarchical and defect-rich Co3 O4 /TiO2 p-n junctions (p-Co3 O4 /n-TiO2 -HPs) are fabricated to implement the sequential catalysis of S8(solid) → Li2 S4(liquid) → Li2 S(solid) . Co3 O4 sheets physiochemically immobilize the pristine sulfur and ensure the rapid reduction of S8 to Li2 S4 , while TiO2 dots realize the effective precipitation of Li2 S, bridged by the directional migration of polysulfides from p-type Co3 O4 to n-type TiO2 attributed to the interfacial built-in electric field. As a result, the sulfur cathode coupled with p-Co3 O4 /n-TiO2 -HPs delivers long-term cycling stability with a low capacity decay of 0.07% per cycle after 500 cycles at 10 C. This study demonstrates the synergistic effect of the built-in electric field and heterostructures in spatially enhancing the stepwise conversion of polysulfides, which provides novel insights into the interfacial architecture for rationally regulating the polysulfide redox reactions.

A tunable triple dissipative solitons (DSs) mode-locked laser without a spectral filter in the all-normal dispersion (ANDi) system is reported and demonstrated. The nonlinear polarization evolution (NPE) acted as an artificial bandwidth filter for formatting the pulses with multiple DSs hysteresis phenomenon and adjusting the output wavelength with tuning. The spectral range can be adjusted from 1036.24 to 1043.44 nm, and the temporal distances between adjacent pulses are all equal to 33.9 ns. With the pump power of 560 mW, the highest output energy of the triple DSs is 48.8 nJ at a repetition rate of 2.541 MHz. Besides, the mode-locking states were stabilized during the wavelength tuning process.

To improve the performance of polyether ether ketone matrix (PEEK) in hard tissue repair and replacement applications, we fabricated graphene (G) reinforced PEEK with graded G concentrations (0.1%-5%) through injection molding. The mechanical properties, surface morphology, chemical composition and thermal stability of the composites have been characterized through universal mechanical testing, scanning electron microscopy, contact-angle measurement, transmission electron microscope, X-ray photoelectron spectroscopy, X-ray diffraction and thermal analysis system. The biocompatibility has been assessed in vitro and the bone repair function of the composite implant have been assessed in vivo using a rabbit mandibular bone defect model. Mechanical testing results suggest that the composite samples have compressive moduli similar to that of the natural bone. Although addition of G into PEEK does not significantly influence the composite tensile, flexural or compressive moduli, it can significantly enhance the ductility and toughness of the material. On the other hand, all G-reinforced PEEK implants demonstrated enhanced adhesion and differentiation of rat bone marrow stromal cells (BMSCs), with 5% G-PEEK showing the highest bioactivity among all samples. The in vivo osseointegration data further revealed that 5% G-PEEK has the best effect in promoting osseointegration and bone regeneration, in both early stage and late stage bone re-growth. Study shows that our G-reinforced PEEK-based implants provides a promising strategy for enhancing the performance of future regenerative bone implants.

The stable hydrogen generation catalysts with favorable performance have been widely studied. As we all know, bimetallic hybrids have been emerged as one type of outstanding electrocatalysts and applied to electrochemical hydrogen generation field. In this work, using bimetallic polyoxometalates (POM) as soft templates and polyethyleneimine (PEI) as carbon source, we synthesized cobalt and tungsten-based bimetallic electrocatalysts (Co/WC@NC) via one-step simple high temperature calcination process.Co/WC@NCexhibits good hydrogen evolution performances. Thereinto, the overpotentials are 129 and 142 mV at the current density of 10 mA cm-2, and the Tafel slopes are 93 and 91 mV dec-1in 0.5 M H2SO4and 1.0 M KOH aqueous solutions, respectively. Furthermore, the catalyst shows good stability for 24 h. The excellent catalytic performance (Co/WC@NC) can be ascribed to the synergistic effect of WC and Co nanoparticles and the protection function of graphitic carbon layers. Furthermore, this work may provide an experimental guidance for the large-scale production of low-cost materials with good catalytic effects.

This paper proposes a novel PV-Trombe wall system combined with phase-change material, which is named as PV-PCM-Trombe system. The work mainly experimentally studies the effectiveness and characteristics of using phase change materials to improve the overheating problem of PV-Trombe wall in summer. Through experiments, the photoelectric performance of the system using phase-change board surfaces with and without a matte black paint lacquer are compared; moreover, the influence on thermal environment of building is evaluated. The results indicate the PV-PCM-Trombe wall system shows an effective cooling effect on PV cell in both experiments and that the surface lacquer coating treatment of PCM plates affects little the photoelectric performance of the system and can reduce the working temperature of PV cell.

Polyaniline (PANI) conductive polymer is a unique energy storage electrode and sensor material. In this article, we report the use of electrochemistry as a quick and easy method to prepare PANI films, which are used as electrode materials to detect the selectivity to various acids. The sample was characterized and tested by XRD, scanning electron microscopy (SEM), BET, and cyclic voltammetry (CV). Various electrochemical parameters were measured and compared for various acids. As an electrode and sensor material, PANI film has different degrees of redox peaks for monobasic acid, dibasic acid, organic macromolecular acid, and inorganic acid. This type of sensor shows good repeatability and reproducibility, so this type of conductive polymer can be used as a sensor material to detect the minimum concentration of acid.

Five BODIPY derivatives containing different number of styryl units were designed and synthesized based on the Knoevenagel reactions. All compounds were characterized by NMR and HRMS. The single crystal structures of compounds 1 and 3–5 were confirmed by X-ray crystallography. The photophysical and electrochemical properties of these dyes were also investigated by UV/Vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. Our study indicates that the optical and electronic properties of the BODIPY derivatives could be easily tuned by the introduction of a various number of styryl units. Their absorption and emission spectra become gradually bathochromically shifted from the red region to the near-infrared region. Their first reduction and first oxidation potential (HOMO-LUMO gap) changes from 2.45 to 1.62 V. The structure-optical property relationships of these compounds are also systematically studied. Furthermore, cellular uptake experiments suggest that compounds 1–3 are membrane permeable and promising fluorophores for bio-labeling/imaging applications.

Metallic phase (1T) MoS2 has attracted enormous attention as an appealing energy storage material for batteries, supercapacitors, and catalysts. However, a facile fabrication method is lacking and the intensive understanding of its sodium storage mechanism is absent. Herein, ultrathin 1T MoS2 nanosheets (1–2 layers) are directly fabricated via and are investigated as an anode material for sodium-ion batteries. Interestingly, the as-prepared 1T MoS2 nanosheets demonstrate a high reversible capacity of 450 mAh g−1 at 50 mA g−1 and outstanding cycling stability with a high capacity retention ratio of 94% after 200 cycles at 1 A g−1, which is far superior to that of the 2H phase counterpart. Density function theory (DFT) calculations show that, in addition to significantly enhanced electronic conductivity, 1T MoS2 also possesses much more sodium philicity and faster Na atom mobility in comparison with the 2H phase. More importantly, as revealed by ex-situ Raman, in-situ X-ray diffraction, and DFT calculations, the 1T MoS2 is more capable of suppressing the dissolution of S species from the material structure compared with the 2H phase, leading to excellent cycling stability. The facile and easily scalable method as well as the deep mechanism analysis will provide a very important reference for the development of high-performance MoS2 anodes and other SIB electrode materials.

Using ab initio calculations, we systemically investigated the energetics and stability of various defects (vacancy, interstitial atom, anti-site defect and dopant atom), optical properties of β-Ga2O3 with O monovacancy, electronic structures of β-Ga2O3 doped with P, Ge, Sn, Si, N and Cl, as well as the effect of the dopant atom on the energetics of monovacancy in these doped β-Ga2O3. From energetic point of view, O atom escapes from the lattice site more easily than Ga atom, thus forming a vacancy and an interstitial O atom. After relaxation, the interstitial Ga/O atom or anti-site defect forms a dumbbell configuration with the neighboring Ga/O atom and the surrounding atoms escape from the initial sites. In addition, existence of a Ga/O vacancy would reduce the formation energy of a new O/Ga vacancy. Both n-type and p-type conduction behaviors have been achieved in Si, Ge, Sn, P, Cl, and N doped β-Ga2O3, where the rarely observed p-type material was obtained by N dopants. However, we have also found that p-type N doped β-Ga2O3 would transform into n-type semiconductor by introducing oxygen/gallium vacancy defects. The atomistic insight into defect stability and electronic structures from the present study is beneficial for fabrication of β-Ga2O3 based semiconductor devices.

The energetics of single and multiple H atoms inside Y2O3, Y2Ti2O7, Y2TiO5, Y3Al5O12 and YAlO3 as well as the migration behavior of H atom have been investigated using first-principles calculations. Among these oxide matrixes, single H atom inside Y2TiO5 is most energetically stable, followed by Y2O3, Y2Ti2O7, Y3Al5O12 and YAlO3. The migration barrier of H atom in Y2O3 is lower than that in other oxide crystals. The formation energy and migration barrier of H atom in those oxide crystals are always higher than that in α-Fe. He atom is more stable than H atom inside oxide crystals, contrarily to the trend in α-Fe solid. Generally, in the cases of Hn (1 ≤ n ≤ 4) atoms inside oxide crystals, the formation energy of even-sized Hn cluster is lower than that of odd-sized Hn clusters, because two H atoms form a hydrogen molecule with strong H–H covalent bond.

Graphene oxide (GO) was synthesized by the modified Hummers method and then reduced with NaBH4 to form RGO with a regular layered structure. The graphene oxide is benzenesulfonated to obtain a functionalized graphene material (RGO-BS). The benzenesulfonated polyaniline/RGO composite (PANI/RGO-BS) was prepared by adsorption double oxidation method using RGO as template. Some physical characterization methods (X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy) were used to analyze the morphology and crystallinity of the composite. The electrochemical properties were characterized by cyclic voltammetry, impedance spectroscopy, galvanostatic charge/discharge, and rate capability. The initial discharge specific capacities of oxidized PANI/RGO-BS and reduced PANI/RGO-BS were 165.4 and 176 mAh/g. After 100 cycles, the capacity retention rates were 92.6% and 96%, the coulombic efficiency of the battery is close to 100%. These results indicate functionalized composite has exciting potentials for the cathode material of lithium-ion battery.

The synergistic interaction of solute O/N atom-vacancy-He in vanadium plays an important role in the evolution of radiation-induced microstructures and He bubbles. We investigate the interactions of He with solute O/N atom, the trapping of He in vacancy-Om/vacancy-Nm complexes and the stability of small vacancy-Om-Hen/vacancy-Nm-Hen clusters (m = 1–2, n = 1–5) in bcc vanadium using first-principles calculations. The interactions between He and O/N impurity are weak repulsion and He at all interstitial sites less than 2.2 A from O (N) atom are unstable. The total binding energies of Hen to vacancy-Om and vacancy-Nm almost linearly increase with the number of He atoms, whose values are from 1.22 eV to 5.01 eV with n from 1 to 5. The vacancy-O(N)-Hen clusters are more stable than vacancy-O2(N2)-Hen clusters. The binding strength of He to vacancy-Om/vacancy-Nm overall has a significant drop compared with those of alone vacancy, and thus He dissolution from both complexes is easier. The existence of the O/N impurities weakens vacancy trapping ability for more He atoms and can reduce the growth and swelling of the trapping He clusters.

Mixed-matrix membranes blended with nanosized inorganic fillers have been widely used in ultrafiltration (UF) for large molecule separation. In this work, we provide a feasible route to construct mixed-matrix polysulfone (PSf) UF membranes via the nonsolvent-induced phase inversion process, utilizing sheet-like copper iodide superstructures (s-CuI) as fillers. The size of s-CuI in lateral dimension reaches micrometer scale, but the nanosheets can be well embedded in the polymer matrix with their 2D basal planes parallel to the membrane surface. On account of the stacking straight-through channel structure of s-CuI and its large dimension spanning across multiple membrane pores within the layer, the PSf membrane blended with 0.8 wt% content of s-CuI displays optimal UF performance with a pure water permeation (PWP) of 1473 L/(m2 h bar) and a bovine serum albumin (BSA) rejection of 92%. In contrast, the pure PSf membrane only presents a PWP of 556 L/(m2 h bar) and a BSA rejection of 58.2%. Besides, the enhancement of mechanical stability for the PSf/s-CuI 0.8% membrane is significant and the leakage of the s-CuI filler is negligible. Though the antifouling performance of the PSf/s-CuI 0.8% membrane against the protein BSA is limited, its flux is always 2–3 times higher than that of the pure PSf membrane in each step during a sequential test of fouling behavior. This study indicates that it is highly promising to employ designable superstructures as functional fillers to construct novel mixed-matrix membranes with good interfacial compatibility and superior performance.

Biocompatible polyetheretherketone (PEEK) is a favorable material for hard tissue repair due to its similar elastic modulus to that of the human bone. In this work, graphene oxide (GO) reinforced PEEK nanocomposites with different GO loading have been prepared by injection molding. Mechanical testing reveals that the toughness of the reinforced composite varies with the GO loading, with 0.5% GO giving the greatest elongation at break (86.32% greater than pristine PEEK). The underlying toughening mechanism has been attributed to the well-dispersed GO forming π-π* conjugations at the GO/PEEK interface. These conjugations also acted as the nucleation sites for oriented crystallized region in PEEK. As the GO content increases further (e.g > 0.5%), the fillers tend to agglomerate and would disturb the crystallites of PEEK and serve as stress concentration sites, resulting in decreased toughness. The biocompatibility of the composites has been evaluated in vitro, and the results showed that the addition of GO into PEEK favors the adhesion and spreading of bone marrow stromal stem cells, demonstrating the strong potential of our GO reinforced PEEK composites in applications such as hard tissue repair and replacement.

A polyaniline/carbon (PANI/C) composite material was synthesized by chemical oxidation polymerization method and was manufactured to the form of gas diffusion electrode inspired by a zinc–air battery, and was used as cathode material. The composite’s structure and morphology of the synthesized polyaniline (PANI) composites were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, and field-emission scanning electron microscopy. The electrochemical properties of the electrodes were examined by electrochemical impedance spectroscopy (EIS), polarization curves, and galvanostatic discharge. The cell voltage kept at 0.88 V for 100 h during the galvanostatic discharge progress at the current of 10 mA and the specific discharge capacity achieved 1850 mAh/g which was 10 times more than the theory value of traditional Zn–PANI battery (about 100–200 mAh/g at the current density of 0.5 mA/cm2). Polyaniline acts as a special catalyst to catalyze oxygen reduction to achieve large capacity.