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Lip seals are one kind of the most widely used rotary seals. Most of the published researches on sealing mechanism cannot describe the mixed lubrication conditions of the sealing zone precisely. In especial, the sealing zone is always assumed to be fall of fluid, resulting in effects of the meniscus and the varying lubricating conditions are neglected. Furthermore, the multiphysics issue is also not handled well up to the present. Hence, a multiphysics sealing mechanism model of rotary lip seals under mixed lubricating conditions is proposed in this paper. Surface tension theory is introduced to determine the location and the surface tension of the ingested meniscus. The fluid–thermal–structural coupling relationship is also considered. The multiphysics coupling issue is handled by iteration method. The proposed model is validated by comparing the simulation results to experimental observations. The effects of the shaft speed and sealing lip roughness on the seal performance are numerically analyzed based on the proposed model. [ABSTRACT FROM AUTHOR]

Cr-doped γ-Fe 2 O 3 /reduced graphene oxide (rGO) nanocomposites are successfully synthesized through a rapid and environmentally friendly microwave method in just 10 min. Under the microwave heating, graphene oxide (GO) is reduced to rGO with ferrous ion (Fe 2+ ) served as the reductant, and Cr-doped γ-Fe 2 O 3 nanoparticles are synthesized in the meantime. It is found that Cr doping can not only affect the phase of Fe 2 O 3 , but also has an effect on the morphology, the electrical conductivity and the electrochemical properties. As anode material for lithium ion batteries, the 4.0 at% Cr-doped γ-Fe 2 O 3 /rGO nanocomposites exhibit the highest reversible capacity of 1060 mAh g −1 after 100 cycles (66.9% of the initial capacity) at a current density of 100 mA g −1 . Furthermore, when assembled as a full cell against commercial cathode including LiCoO 2 and LiNi 1/3 Mn 1/3 Co 1/3 O 2 , the battery shows promising cycling performance. The superior electrochemical performance could be attributed to the uniform nanostructure and the synergistic effect between Fe 2 O 3 and rGO as well as the doping of chromium, which can reduce the size of Fe 2 O 3 particles and improve the electrical conductivity. [ABSTRACT FROM AUTHOR]

CeO 2 /ionic liquid (IL) hybrid material has been successfully prepared by a facile ionothermal route under relatively mild temperature. When using it as sensing material for humidity sensor, the CeO 2 /IL hybrid material exhibits ultrafast response (4 s) and recovery (<1 s) performance. This result ranks it among the fastest ever reported values for humidity detection based on metal oxide sensor. [ABSTRACT FROM AUTHOR]

Abstract: Since the discovery of graphene in 2004, research on 2D materials has grown rapidly. Compared to their bulk counterparts, 2D atomically thin, layered transition‐metal dichalcogenides (TMDCs or MX2) nanosheets exhibit excellent electronic and optical properties, outstanding mechanical flexibility, and exceptional catalytic performance. As a representative of 2D materials, MX2 holds great promise in many potential applications, especially in energy‐related applications. Here, a brief overview of atomically thin layered MX2 nanosheets applied in energy storage and conversion systems is presented. Firstly, the crystal structures and phases, morphologies, and synthesis methods of MX2 are discussed. Sequentially, the achieved progress on atomically thin MX2 in energy‐related applications (i.e., the hydrogen‐evolution reaction, oxygen‐evolution reaction, CO2 electrochemical reduction, electrochemical capacitors, lithium‐ion batteries, sodium‐ion batteries, and lithium–sulfur batteries) is systematically discussed. Finally, the conclusions and some prospects regarding atomically thin MX2 for applications in the field of energy‐storage systems are provided. [ABSTRACT FROM AUTHOR]

C,N-LiFePO4 mesocrystals were successfully prepared through topotactic conversion of ferric giniite using an ionic liquid as a carbon and nitrogen source, which provided a pathway for rapid electron transfer and shortened the Li+ diffusion distances. Thus, good cycling stability and rate capability are achieved, showing improvement using the strategy of mesocrystalline electrodes coated with N-doped carbon from an ionic liquid. [ABSTRACT FROM AUTHOR]

We reported the facile synthesis of hollow carbon nanofibers/MnO 2 (CNFs/MnO 2 ) composites for high performance supercapacitor electrodes. The nanocomposites were prepared via electrospinning of carbon nanofibers/MnOx and subsequent hydrothermal coating of MnO 2 nanosheets on the surface. The unique hollow structure and numerous MnO 2 nanosheets increased the contact area between the electrodes and electrolyte so that the CNFs/MnO 2 electrode exhibited higher electrochemical performance than the CNFs/MnOx composites. The CNFs/MnO 2 composites displayed a specific capacitance of 151.1 F/g at 1 A/g, and 90% of the initial specific capacitance was maintained after 8000 cycles. An asymmetric supercapacitor was assembled with the CNFs/MnO 2 composites and the active carbon. The asymmetric supercapacitor exhibited a high performance in 1 M Na 2 SO 4 aqueous solution with a working potential window ranging from 0 to 1.8 V. Furthermore, the asymmetric supercapacitor possessed a cycling stability with 93.5% capacitance retained after 1500 cycles at 1 A/g. [ABSTRACT FROM AUTHOR]

Novel α-Ag3VO4 nanostructures have been successfully synthesized via a facile and repeatable precipitation method by using n-BA as precipitant and complexing agent. Photocatalytic property tests for decomposition of RhB demonstrate that the as-prepared nanostructures have enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

In the work presented here, well-dispersed ferric giniite microcrystals with controlled sizes and shapes are solvothermally synthesized from ionic-liquid precursors by using 1- n-butyl-3-methylimidazolium dihydrogenphosphate ([Bmim][H2PO4]) as phosphate source. The success of this synthesis relies on the concentration and composition of the ionic-liquid precursors. By adjusting the molar ratios of Fe(NO3)3 ⋅9H2O to [Bmim][H2PO4] as well as the composition of ionic-liquid precursors, we obtained uniform microstructures such as bipyramids exposing {111} facets, plates exposing {001} facets, hollow spheres, tetragonal hexadecahedron exposing {441} and {111} facets, and truncated bipyamids with carved {001} facets. The crystalline structure of the ferric giniite microcrystals is disclosed by various characterization techniques. It was revealed that [Bmim][H2PO4] played an important role in stabilizing the {111} facets of ferric giniite crystals, leading to the different morphologies in the presence of ionic-liquid precursors with different compositions. Furthermore, since these ferric giniite crystals were characterized by different facets, they could serve as model Fenton-like catalysts to uncover the correlation between the surface and the catalytic performance for the photodegradation of organic dyes under visible-light irradiation. Our measurements indicate that the photocatalytic activity of as-prepared Fenton-like catalysts is highly dependent on the exposed facets, and the surface area has essentially no obvious effect on the photocatalytic degradation of organic dyes in the present study. It is highly expected that these findings are useful in understanding the photocatalytic activity of Fenton-like catalysts with different morphologies, and suggest a promising new strategy for crystal-facet engineering of photocatalysts for wastewater treatment based on heterogeneous Fenton-like process. [ABSTRACT FROM AUTHOR]

Well-dispersed ammonium aluminum carbonate hydroxide (NH4-Dw) and γ-AlOOH nanostructures with controlled morphologies have been synthesized by employing an ionic-liquid-assisted hydrothermal process. The basic strategies that were used in this work were: 1) A controllable phase transition from NH4-Dw to γ-AlOOH could be realized by increasing the reaction temperature and 2) the morphological evolution of NH4-Dw and γ-AlOOH nanostructures could be influenced by the concentration of the ionic liquid. Based on these experimental results, the main objective of this work was to clarify the effect models of the ionic liquids on the synthesis of NH4-Dw and γ-AlOOH nanostructures, which could be divided into cationic- or anionic-dominant effect models, as determined by the different surface structures of the targets. Specifically, under the cationic-dominant regime, the ionic liquids mainly showed dispersion effects for the NH4-Dw nanostructures, whereas the anionic-dominant model could induce the self-assembly of the γ-AlOOH particles to form hierarchical structures. Under the guidance of the proposed models, the effect of the ionic liquids would be optimized by an appropriate choice of cations or anions, as well as by considering the different effect models with the substrate surface. We expect that such effect models between ionic liquids and the target products will be helpful for understanding and designing rational ionic liquids that contain specific functional groups, thus open up new opportunities for the synthesis of inorganic nanomaterials with new morphologies and improved properties. In addition, these as-prepared NH4-Dw and γ-AlOOH nanostructures were converted into porous γ-Al2O3 nanostructures by thermal decomposition, whilst preserving the same morphology. By using HRTEM and nitrogen-adsorption analysis, the obtained γ-Al2O3 samples were found to have excellent porous properties and, hence, may have applications in catalysis and adsorption. [ABSTRACT FROM AUTHOR]

In this work, a novel lead sulfide (PbS) hierarchical superstructure, denoted as octapodal dendrites with a cubic center, has been synthesized employing a simple single-source precursor route. Our experimental results demonstrate that the novel hierarchical superstructure was generated through the delicate balance between the kinetic growth and thermodynamic growth regimes. Moreover, the morphology of PbS crystals can be controlled by adjusting the solvent under a thermodynamically or kinetically controlled growth regime. It is highly expected that these findings will be useful in understanding the formation of PbS nanocrystals with different morphologies, which are also applicable to other face-centered cubic nanocrystals. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized CoCO3 microaggregation, microcubes and nanoplates by an ionic liquid-assisted hydrothermal method. The morphologies of the CoCO3 crystals depend on the concentration of the ionic liquid and the reaction temperature. Moreover, the as-prepared CoCO3 crystals can serve as a useful precursor to obtain porous Co3O4 particles with similar morphology by means of calcinations. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Photocatalytic production from water is considered an effective solution to fossil fuel-related environmental concerns, and photocatalyst surface science holds a significant interest in balancing photocatalysts' stability and activity. We propose a plasma-wind method to tune the surface properties of a photocatalyst with an amorphous structure. Theoretical calculation shows that the amorphous surface structure can cause an unsaturated coordination environment to adjust the electron distribution, forming more adsorption sites. Thus, the photocatalyst with a crystal–amorphous (C–A) interface can strengthen light absorption, harvest photo-induced electrons, and enrich the active sites, which help improve hydrogen yield. As a proof of concept, with indium sulfide (In2S3) nanosheets used as the catalyst, an impressive hydrogen production rate up to 457.35 μmol cm−2 h−1 has been achieved. Moreover, after plasma-assisted treatment, In2S3 with a C–A interface can produce hydrogen from water under natural outdoor conditions. Following a six-hour test, the rate of photocatalytic hydrogen evolution is found to be 400.50 μmol cm−2 g−1, which demonstrates that a catalyst prepared through plasma treatment is both effective and highly practical. [ABSTRACT FROM AUTHOR]

The steep rhombohedra MnCO3microcrystals and their large-scale assembly into regular elongated patterns are obtained viaa novel surfactant-free route by adjusting the proportion of the mixed solvent (methanol and DMF). We hope this synthetic strategy can provide a new approach to synthesize metal carbonates. [ABSTRACT FROM AUTHOR]

High‐capacity O3‐type layered sodium oxides are considered one of the most promising cathode materials for the next generation of Na‐ion batteries (NIBs). However, these cathodes usually suffer from low high‐rate capacity and poor cycling stability due to structure deformation, native air sensitivity, and interfacial side reactions. Herein, a multi‐site substituted strategy is employed to enhance the stability of O3‐type NaNi0.5Mn0.5O2. Simulations indicate that the Ti substitution decreases the charge density of Ni ions and improves the antioxidative capability of the material. In addition, the synergistic effect of K+ and Ti4+ significantly reduces the formation energy of Na+ vacancy and delivers an ultra‐low lattice strain during the repeated Na+ extraction/insertion. In situ characterizations verify that the complicated phase transformation is mitigated during the charge/discharge process, resulting in greatly improved structure stability. The co‐substituted cathode delivers a high‐rate capacity of 97 mAh g−1 at 5 C and excellent capacity retention of 81% after 400 cycles at 0.5 C. The full cell paired with commercial hard carbon anode also exhibits high capacity and long cycling life. This dual‐ion substitution strategy will provide a universal approach for the new rational design of high‐capacity cathode materials for NIBs. [ABSTRACT FROM AUTHOR]

Ammonium phosphate ((NH4)3PO4) has been first used as a surface treatment reagent for Li-rich cathode materials. Compared to the conventional surface treatment, the samples treated with (NH4)3PO4 exhibit an ultra-high initial Coulomb efficiency of 98.0% and excellent cycling stability. This is mainly attributed to the simultaneous construction of surface integrated structures, including oxygen vacancies, spinel phases, and Li3PO4 coating. This study demonstrates the effectiveness of ammonium phosphate surface treatment and provides a new idea for designing other cathode materials. [ABSTRACT FROM AUTHOR]

Review: 85 refs. [ABSTRACT FROM AUTHOR]

Mixed Co x Sn y @C nanocomposites have been synthesized by heat treatment of CoSn(OH) 6 with oleic acid in Ar. When tested as anode materials in Li-ion batteries, the as-obtained mixed Co x Sn y @C nanocomposites exhibit excellent lithium storage performance, delivering a reversible capacity of 553.6 mAh g −1 after 50 cycles at 50 mA g −1 . The Co x Sn y @C nanocomposites are promising anode materials for high-performance Li-ion batteries in the future. [ABSTRACT FROM AUTHOR]

The hetero-structures of chemically distinct materials have been regarded as superior anode materials, since they could effectively overcome the large capacity fading due to the characteristics of their structures. Herein, Cd–Sn–SnO 2 @C heterocomposite has been synthesized by carbon reduction of CdSnO 3 during carbonization of oleic acid. Electrochemical results show that the as-obtained Cd–Sn–SnO 2 @C electrode could maintain a discharge capacity of 571.4 mAh g −1 at a current density of 50 mA g −1 after 50 cycles. It demonstrates that the as-synthesized Cd–Sn–SnO 2 @C heterocomposite might be a promising anode material for high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) possess effective functions in controlling the phase and morphology of nanomaterials. However, it is still unclear how ILs affect the morphology control and what the origin of adsorption selectivity of ILs is on different crystal facets. It is a challenge to develop a simple method to select the suitable kinds of ILs for achieving the controllable synthesis of nanomaterials with designable shape. Herein, density functional theory (DFT) calculations were combined with experiment to study the interaction mechanism between ILs and crystal facets. An important relationship is proposed, named as the geometric matching principle, in which the adsorption site of substrate should not only need to meet the space requirement for interionic stacking of ILs, but also needs to maximize the interaction between adsorbed ILs and substrate. This new finding is meaningful for prediction of the adsorption selectivity of ILs and clarification of their shape-controlled chemistry. [ABSTRACT FROM AUTHOR]

Aqueous electrolyte‐based batteries have attracted increasing attention because of nonflammability, low cost, high power density, and environmental friendliness. However, the low energy density of aqueous lithium‐ion batteries caused by the narrow stable electrochemical window of water and electrode materials with low capacity severely limits their further development. In this regard, the development of metal anodes with high specific capacity shows excellent prospects. For example, metal zinc and aluminum anodes have high theoretical specific capacity, rich resources, and environmental friendliness, and can be used as promising anodes for high‐energy‐density aqueous rechargeable metal batteries. Unfortunately, metal anodes usually face balance issues with regard to stability and activity associated with dendrite growth and undesired side reactions in water‐based electrolytes, which is still a great challenge for aqueous metal batteries. In this review, various aqueous metal batteries including aqueous rechargeable metal batteries and aqueous metal–air batteries are summarized and highlighted. Recent advances in the design of high‐safety aqueous electrolytes and the strategies for metal anode protection are comprehensively reviewed. In addition, emerging challenges and some perspectives on the development of high‐energy‐density aqueous metal batteries are included. [ABSTRACT FROM AUTHOR]

High‐energy‐density batteries have attracted significant attention due to the huge demand in electric transportation in future. Metal‐based batteries, especially lithium metal batteries (LMBs) and sodium metal batteries (SMBs), have been hot research topics nowadays. The uncontrolled growth of metal dendrites has retarded the development of LMBs and SMBs. Various electrolytes have been explored to meet the demand of high‐performance metal‐based batteries, such as additives‐contained electrolytes, polymer electrolytes, and solid‐state electrolytes. To guide the development of electrolytes in LMBs and SMBs, we organize this roadmap to give out the status of present research and future challenges in this field. We also hope that the readers can get the knowledge and ideas from this roadmap. [ABSTRACT FROM AUTHOR]

In pursuit of high‐performance cathode materials for lithium‐ion batteries with high energy and power densities, porous LiFe0.4Mn0.6PO4/CNF free‐standing electrodes have been successfully prepared through a facile ionic liquid (IL) assisted electrospinning method. Owing to the hierarchical porosity and N‐doped carbon layer derived from the ionic liquid, the resulting electrodes exhibited superior electrochemical performances with an improvement of conductivity and pseudocapacitive contribution, delivering a discharge capability of 162.7, 133.5, 114.5, and 102.6 mAh g−1 at the current rates of 0.1, 1, 5, and 10 C, respectively. It is highly expected that this facile IL‐assisted electrospinning method will lead to further developments for other phosphate‐based free‐standing electrodes, which offers a new route in designing polyanionic cathodes for high‐performance Li‐ion batteries. [ABSTRACT FROM AUTHOR]

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on 'Carbon Materials in Energy Storage and Conversion'. [ABSTRACT FROM AUTHOR]

Abstract The effect of niobium (Nb) doping in one-dimensional (1D) nanostructured LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) cathode has been investigated for this study. Nb-doped NCM nanofibres have been prepared through an electrospinning method followed by controllable sintering process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed that Nb-doping can effectively reduce cation mixing, thus improve the structural stability. In addition, due to the valence compensation balance, Mn4+ ions are partially reduced to Mn3+ ions, which can further improve the conductivity and stable cycling performance. Therefore, increased discharge capacities, high first cycle efficiencies and superior cycling and rate behaviors are observed between normal voltage limits for the Nb-doped NCM compositions in electrochemical cells. Specifically, Nb-doped NCM nanofibres achieve a high discharge capacity of 200.4 mAh/g at 0.1 C with a high Coulombic efficiency of 92.3%. Moreover, a high discharge capacity of 118.7 mAh/g even at 5 C with 83.3% capacity retention after 200 cycles is also achieved. Also, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results demonstrate that Nb-doping can mitigate the electrochemical polarization of NCM and improve the lithium ion diffusion coefficient, leading to the improvement of electrochemical performances. It is highly expected that our findings can provide a general approach to improve the electrochemical properties of cathode materials for lithium-ion batteries. Graphical abstract 1D Nb-doped LiNi 1/3 Co 1/3 Mn 1/3 O 2 nanofibres (Nb-NCM) have been fabricated by an electrospinning method. When used as cathodes in lithium-ion batteries, Nb-NCM electrode manifests excellent cycling stability and rate capability. Image 1 Highlights • 1D Nb-doped LiNi 1/3 Co 1/3 Mn 1/3 O 2 has been successfully fabricated by an electrospinning technique. • The effect of Nb-doping has been proposed. • 1D Nb-NCM nanofibres manifest excellent cycling stability and rate capability. [ABSTRACT FROM AUTHOR]

Graphical abstract In situ-growth of 1T/2H-MoS 2 nanosheets on the CFC, ultra-small SnS 2 nanoparticles are anchored on the surface of MoS 2 nanosheets unifromly. When the SnS 2 /MoS 2 /CFC composites applied as a binder-free flexible anode, it exhibits excellent performances. A highly flexible full cell was fabricated, demonstrating remarkable flexibility and cycling stability. Highlights • In-situ growth SnS 2 /MoS 2 on CFC by a hydrothermal method and water bath process. • SnS 2 /MoS 2 shows a capacity of 1294 mA h g−1 at 0.1 A g−1 after 120 cycles. • The distribution of SnS 2 on 1T/2H-MoS 2 can enhance electrochemical properties. • A full cell is fabricated, showing high flexibility and electrochemical properties. Abstract Flexible lithium ion batteries are important for wearable electronic devices. Herein, 1T/2H phase MoS 2 nanosheets are grown on carbon fiber cloth, and the ultra-small SnS 2 nanoparticles are anchored in the surface of MoS 2 nanosheets uniformly. We fabricate the hierarchical nanostructures via a hydrothermal method then water bath process. During in-situ growth of 1T/2H phase MoS 2 , urea is used as the surfactant and NH4+ (produced by urea and ammonium molybdate tetrahydrate) is acted as insertion guest ions to stabilize 1T phase MoS 2. The synergistic effects between MoS 2 nanosheets and SnS 2 nanoparticles can improve structural stability of the electrode and significant enhance the transport of Li ions and electrons, thereby ameliorate the electrochemical properties. When applied as a binder-free, flexible Li-ion battery anode, it exhibits admirable cycling stability and excellent rate performance. Due to the presence of 1T phase MoS 2 and uniform distribution of ultra-small SnS 2 nanoparticles on MoS 2 nanosheets, the SnS 2 /MoS 2 /carbon fiber cloth composites maintain 1294 mA h g−1 when cycling at 100 mA g−1 after 120 cycles. A highly flexible battery based on SnS 2 /MoS 2 /carbon fiber cloth and LiCoO 2 is fabricated, demonstrating excellent mechanical flexibility and cycling stability. [ABSTRACT FROM AUTHOR]

Noble metal-semiconductor gas sensors have attached much attention owing to its high sensitivity and excellent selectivity. In this work, non-stoichiometry urchin-like Pd-W 18 O 49 nanostructures are developed for gas sensing applications. Such hierarchical nanostructures were synthesized by two-step approach including a hydrothermal reaction and a subsequent incipient wetness impregnation process. The high sensitivity and excellent selectivity distinguish this sensor from the traditional Pd-WO 3 sensor. An insight into the outstanding performance of Pd-W 18 O 49 is provided by contrasting the sensing characteristics of W 18 O 49 and Pd-WO 3 , which exhibit lower selectivity and response to hydrogen. By comparison, the observed response of Pd-W 18 O 49 sensor is up to 1600– in 0.1 vol% hydrogen at a low working temperature of 100 °C. The excellent and enhanced H 2 sensing performances of Pd-W 18 O 49 sensor can be attributed to its novel hierarchical structure, abundant oxygen vacancies, and the catalytic activity of Pd nanoparticles. [ABSTRACT FROM AUTHOR]

Uniform octahedral nickel ferrite nanocrystals wrapped by graphene (GNFO) have been synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis techniques, which reveal that the NiFe 2 O 4 nanocrystals are enclosed by high index (111) facets and encapsulated by reduced graphene oxide sheets. When applied as anode electrodes for lithium ion batteries, GNFO nanocomposites present excellent electrochemical performances. The electrode maintains 1275 mAh g −1 after 30 cycles at 0.1 A g −1 and a reversible capacity up to 937 mAh g −1 after 250 cycles at 1 A g −1 . A prominent rate capability is also obtained and the specific capacity remains 312 mAh g −1 at 10.0 A g −1 . The superior electrochemical properties could benefit from open surface structure of octahedral NiFe 2 O 4 and synergistic effect between graphene and NiFe 2 O 4 , which shows promising applications in lithium-ion storage devices. [ABSTRACT FROM AUTHOR]

A novel gas induced modulating effect on gas sensing was observed with Bi 2 WO 6 nanoparticles based gas sensors in ethanol-ammonia dual gas system at room temperature. The sensors presented high response to ammonia at room temperature, while no response to other common reducing gases such as hydrogen, ethanol, acetone, and carbon monoxide. Similar outstanding selectivity to ethanol at elevated temperatures (such as 250 °C) was also obtained. Interestingly, the sensors exhibited a reduced response with a sharp conductance increase during the recovery process in the co-presence of ammonia and ethanol, as compared to that only in the presence of ammonia. And the gas response to certain amount of ammonia decreased with increasing the concentration of ethanol in the background. This abnormal sensing behavior in the dual gas system was ascribed to the result of multistep gas adsorption and desorption processes on material surface. On the basis of surface reactions between targeted gases and active oxygen species adsorbed on sensing materials, cross-sensitivity is one of the most significant concerns in semiconductor oxide based gas sensing. However, this work might give a new insight into the interference in multi-component gas sensing which occurs within targeted gases, and also indicate an indirect room temperature gas detection strategy. [ABSTRACT FROM AUTHOR]

Hierarchical SnO 2 /α-Fe 2 O 3 bilayer hollow spheres with thin inner shell were successfully synthesized by using SnO 2 contained carbon spheres as sacrificial templates. The heterojunction formed at the interface as well as the hierarchical structures which provide an effective gas diffusion path resulted in significant enhancement in sensing response to ethanol and acetone as compared to pristine urchin-like α-Fe 2 O 3 . Response values of the hollow spheres based sensors towards 100 ppm acetone and ethanol could reach to 47.1 and 29.5. Moreover, in contrast to many other types of α-Fe 2 O 3 /SnO 2 composites reported previously, gas sensors based on the bilayer hollow spheres here exhibited ultra-fast response and recovery speed. The dynamic transients of the sensors demonstrated both their fast response (3–4 s) and fast recovery (6–9 s) towards acetone in the concentration of 10–100 ppm. The unique hierarchical hollow structure with thin inner shell might be responsible for the ultra-fast gas sensing properties. This simple template based strategy is expected to be extended for the fabrication of similar hollow structure semiconductor oxide composites, and this work might provide an effective principle for designing high performance hybrid gas sensing materials. [ABSTRACT FROM AUTHOR]

We first report the pure H x MoO 3 nanobelts as anode for lithium-ion batteries by a facile hydrothermal with ammonium heptamolybdate tetrahydrate ((NH 4 )6Mo 7 O 24 ∙4H 2 O) and hydrochloric acid (HCl). Owing to hydrogen-doping, Mo 5+ exists in the H x MoO 3 nanobelt, which may release extra electrons. Therefore, the electric conductance of H x MoO 3 nanobelt is enhanced greatly. Moreover, the content of hydrogen can’t be high, since the ordered structure deteriorates when amount of hydrogen increasing. The H 0.28 MoO 3 nanobelts we designed exhibit outstanding specific capacity and rate performance. The stable capacity of 920 mAh g −1 is obtained after 25 charge/discharge cycles at 100 mA g −1 . At high current densities such as 1, 2, 5 and 10 A g −1 , the H 0.28 MoO 3 electrode delivers specific capacities of about 600, 500, 420, 300 mAh g −1 , respectively. Even after 450 charge discharge cycles at 1 A g −1 , the performance of our materials can maintain the capacity of about 550 mAh g −1 . Furthermore, we provide more discussion about the lithium storage mechanism of H x MoO 3 nanobelts through ex situ XRD and FESEM. By comparing H x MoO 3 with different X, we find that low content of hydrogen can greatly improve the performance of α-MoO 3 electrodes in Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional (1D) ZnCo2O4 porous nanotubes (PNTs) have been synthesized using a simple technique of electrospinning followed by calcination in air and firstly applied in supercapacitors (SCs). The obtained ZnCo2O4 nanomaterial displays 1D architecture with a highly porous nature and hollow interiors. This unique structure significantly enlarged the electroactive surface areas of the ZnCo2O4, leading to better electrolyte/electrode contact, more efficient transport pathways and good strain accommodation. Our experimental results demonstrate that it exhibits a high specific capacitance of 770 F g−1 at 10 A g−1, excellent rate property (84% of the capacity retention at 60 A g−1) and good cycling stability of only 10.5% loss after 3000 cycles. Compared with the ZnCo2O4 nanoparticals, such obtained PNTs possess enhanced rate and capacitive properties. Our work confirms the as-prepared ZnCo2O4 PNTs can serve as advanced SCs materials. It is highly expected this simple method of electrospinning can be extended to prepare other superior electrochemical materials. [Copyright &y& Elsevier]

The Bi2S3nanomaterials with various morphologies such as nanorods, nanowires, nanowire bundles, urchin-like microspheres and urchin-like microspheres with cavities have been successfully synthesized through a simple hydrothermal method. Experimental results indicate that sulfur sources play crucial roles in determining the morphologies of Bi2S3products. Moreover, formation mechanisms of different Bi2S3nanostructures are discussed based on understanding of the growth habit of Bi2S3crystal. Finally, we also studied the morphologies-dependent electrochemical and optical properties of the as-synthesized Bi2S3nanomaterials. [ABSTRACT FROM AUTHOR]

Morphology control of bismuth sulfide (Bi2S3) nanostructures, from one-dimensional nanorods with various aspect ratios, to various kinds of two-dimensional nanofabrics (dense nanofabrics and spark nanofabrics) to three-dimensional urchin-like microspheres and crossed nanofabrics, has been achieved viaan ionic liquids-assisted hydrothermal route, by adjusting the active state of the BiOCl, the characteristics and concentration of the ionic liquid used and the reaction temperature. Reasonable growth mechanisms for the Bi2S3with different morphologies are proposed, based on active state of the intermediate BiOCl, characteristics of the ionic liquids used and the crystal growth habits of Bi2S3. More importantly, we introduce the concept of two different states of the intermediate BiOCl (active BiOCl and inert BiOCl) to explain the growth mechanisms of nanofabrics, nanorods and urchin-like microspheres, from different crystal growth processes. Moreover, electrochemical measurements demonstrate that Bi2S3nanofabrics and urchin-like microspheres possess higher initial Li intercalation capacity than graphitic materials (372 mA h g−1), and their cyclic performances are highly dependent on their morphologies. [ABSTRACT FROM AUTHOR]

Ferrimagnetic Fe3S4nanowalls and triple hierarchical microspheres have been fabricated viaan ionic liquid-modulated solution–phase process, respectively. Magnetic hysteresis measurements demonstrate that their morphology–dependent magnetic properties might be originated from their unique nanostructures. [ABSTRACT FROM AUTHOR]

The swelling mechanism is widely used to explain the response of ionic liquids (ILs) or poly(ionic liquid)s (PILs) to moisture. While a fairly broad consensus has been attained, there are still some phenomena that are not well explained. As a complement to the swelling mechanism, we systematically studied the free volume theory in the rapid response and recovery of PIL humidity performance. We chose poly(1-ethyl-3-vinylimidazolium bromide) (PIL-Br), poly(1-ethyl-3-vinylimidazolium tetrafluoroborate) (PIL-BF4) and poly(1-ethyl-3-vinylimidazolium bis(trifluoromethane sulfonimide)) (PIL-TFSI) as model materials and investigated the impact of PIL structure including anion type, film thickness and affinity to moisture on performance to obtain the humidity sensing mechanism for PILs based on free volume theory. Hence, we can combine free volume theory with the designed PIL structures and their affinity with moisture to obtain a high concentration of free ions in PIL sensing films. Furthermore, the PIL humidity sensors also show fast, substantial impedance changes with changing humidity for real-time monitoring of the human respiratory rate due to a fast response and recovery performance. Therefore, our findings develop a new perspective to understand the humidity performance of PILs based on free volume theory, resulting in fast response and recovery properties realized by the rational design of PIL sensing films. [ABSTRACT FROM AUTHOR]

Layered lithium-rich manganese oxide (LLO) cathode materials have attracted much attention for the development of high-performance lithium-ion batteries. However, they have suffered seriously from disadvantages, such as large irreversible capacity loss during the first cycle, discharge capacity decaying, and poor rate performance. Here, a novel method was developed to coat the surface of 0.4Li2MnO3∙0.6LiNi1/3Co1/3Mn1/3O2 cathode material with reduced graphene-oxide (rGO) in order to address these drawbacks, where a surfactant was used to facilitate the well-wrapping of rGO. As a result, the modified LLO (LLO@rGO) cathode exhibits superior electrochemical performance including cycling stability and rate capability compared to the pristine LLO cathode. In particular, the LLO@rGO with a 0.5% rGO content can deliver a high discharge capacity of 166.3 mAh g−1 at a 5C rate. The novel strategy developed here can provide a vital approach to inhibit the undesired side reactions and structural deterioration of Li-rich cathode materials, and should be greatly useful for other cathode materials to improve their electrochemical performance. [ABSTRACT FROM AUTHOR]