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High surface states density of hematite photoanodes results in their low water oxidation kinetics and high surface electrons-holes recombination. To overcome these inherent drawbacks, various methods have been adopted, especially loading oxygen evolution catalysts and depositing oxide passivation layers. We report here an efficient way to promote the photocurrent of Fe 2 O 3 photoanodes via depositing a thin layer of Co 0.84 Ni 0.16 -Pi. With the Co 0.84 Ni 0.16 -Pi deposit on its surface, the photocurrent density of Fe 2 O 3 increases by ca. 42% at 0.23 V vs. Ag/AgCl, and the onset potential shifts 200 mV cathodically. In contrast, Co-Pi@Fe 2 O 3 photoanode shows only 20% enhancement in photocurrent density under otherwise identical condition. The dark current densities of the photoanodes give an evidence that both Co 0.84 Ni 0.16 -Pi and Co-Pi are good oxygen evolution catalysts. Moreover, different from sparsely distributed Co-Pi nanoparticles, a 2–3 nm amorphous Ni doped cobalt phosphate layer can be also an effective passivation layer for surface states of hematite, which has been demonstrated by the analyses of Mott-Schottky plots and electrochemical impedance spectroscopy. This work demonstrates the dual roles of an amorphous oxygen evolution co-catalyst on hematite photoanodes and provides a simple method for designing highly efficient photoanodes. [ABSTRACT FROM AUTHOR]

This study quantified the spatial pH distributions within an electricity-producing biofilm and its concentration boundary layer, as well as the bulk solution by employing pH microelectrode. The relationship between pH distributions and current densities was explored. It was found that (1) pH level near the anode surface was detected as low as 5.57 compared to 6.90 of the bulk solution across a 350 μm thick Geobacter biofilm; (2) the average pH levels within the biofilm decreased over time; (3) pH variations within the biofilm shifted the midpoint potential of Cyclic Voltammetry with 59.0 mV per pH; (4) pH level near the anode surface was as low as 4.91 for a 25 mM phosphate buffer solution compared to 5.73 of that for the 100 mM. Furthermore, a method was recommended to estimate the thickness of biofilm by plotting the derivative of pH-depth profile. [ABSTRACT FROM AUTHOR]

Urine-powered microbial fuel cells (UMFCs) can recover energy from urine, a typical constituent of urban wastewater. Three-dimensional (3D) structure is advantageous for improving the anode performance, especially using carbon nanotube (CNT), which has good biocompatibility. It is proposed in this paper to use 3D carbon nanotube sponge (3DCS), which has a proper size of pores as anodes for UMFCs. The maximum output voltage is as high as 231.89 mV, and the power density is 1.24 W m−3(per anode volume). The results show that 3DCS is a good choice for fabricating 3D anode for UMFCs. [ABSTRACT FROM PUBLISHER]

Abstract: The three-dimensional (3D) macroporous anodes were constructed by coating carbon nanoparticles (graphene, carbon nanotube, or activated carbon) on stainless steel fiber felts (SSFFs) that have an open, solid and macroporous structure. These modified electrodes provided large surface area for reaction, interfacial transport and biocompatible interface available for bacterial colonization and substrate transport. Graphene modified anode delivered a maximum power density of 2142 mW m−2 at a current density of 6.1 A m−2 in MFC, greatly improved the performance of MFC compared with the unmodified SSFF-MFC. Electrochemical impedance spectroscopy (EIS) measurements together with the polarization curves demonstrated that carbon nanoparticles modified anodes could greatly decrease MFCs' internal resistance. Our experimental results also proved that embedding carbon nanoparticles into 3D macroporous metallic scaffold is a promising method for MFC anode fabrication. [Copyright &y& Elsevier]

Abstract: A novel microbial fuel cell (MFC) anode is fabricated by electrochemically reducing graphene oxide (ERGNO) first and coating polyaniline (PANI) nano-fibers afterward on the surface of carbon cloth (CC). ERGNO/CC is prepared using an electrochemical synthesis method reducing graphene oxide by cyclic voltammetry (CV) in phosphate buffer solution (PBS, pH = 6.9). Combining the advantages of PANI and ERGNO, PANI–ERGNO/CC yields a maximum power density of 1390 mW m−2 when used as the MFC anode, which is 3 times larger than that of the MFC with the CC anode. The electrodes are characterized by scanning electron microscopy (SEM) and Raman spectroscopy. The electrochemical activities have been investigated by CV and electrochemical impedance spectroscopy (EIS). The great improvement is attributed to the fact that graphene not only serves as a highly conductive support material, but also provides large surface for PANI. High conductivity and large specific surface area greatly improve the charge transfer efficiency and the bacterial biofilm loading. In this work, a practical and promising synthesis method is developed to fabricate high-performance MFC anodes. [Copyright &y& Elsevier]

Abstract: The derivatives of 4,5-diazafluorene-9-one-benzoylhydrazone (1–4) and 2-pyridine-carboxaldehyde-benzoylhydrazone (5–9) were prepared. The compounds 1–4 reacted with Ni(Ac)2·4H2O to form diaquabis[4,5-diazafluorene-9-one-benzoylhydrazone]nickel(II) (10–13), while the compounds 5–9 reacted with (DME)NiBr2 to form bis[N-(pyridine-2-carboxaldehyde-benzoylhydrazone)]nickel(II) dibromide (14–18), respectively. All ligands and complexes were characterized by elemental analysis and spectroscopic analysis, along with the X-ray single crystal diffraction techniques for 10, 13 and 14. The nickel(II) centers are six-coordinated with two corresponding ligands and two coordinated solvents for 10–13, while the geometry around the nickel atom of 14–18 is distorted octahedron with two ligands and two bromides. Activated with methylaluminoxane, all nickel complexes show good activities for vinyl polymerization of norbornene and considerable activities for ethylene oligomerization at ambient pressure. By using 10, the influence of reaction conditions was carefully examined on the catalytic behavior of vinyl polymerization of norbornene. The catalytic conditions were varied to investigate their effects on activity of ethylene oligomerization. The resulting poly(norbornene)s were characterized by IR, 1H NMR, TGA, DSC and the viscosity measurement. [Copyright &y& Elsevier]

The ethylene oligomerization was investigated by using new hydrazone nickel complexes Ni(N∧O)2Cl2 (2a, N^O=4,5-diazafluorene-9-one-benzoylhydrazone; 2b, N^O=4,5-diazafluorene-9-one-4-nitrobenzoylhydrazone; 2c, N^O=4,5-diazafluorene-9-one-3-nitrobenzoylhydrazone) with methylaluminoxane (MAO) in toluene. Those catalytic systems mainly assisted the dimerization of ethylene with good catalytic activity (105 to 104 g mol−1 h−1) at ambient pressure. The reaction conditions, such as the ratios of Al/Ni, reaction temperature and reaction time, were investigated. The best catalytic activity for the three complexes was observed for complex 2a without nitro-substituent on its aryl ring. [Copyright &y& Elsevier]

Power density and overall-cell polarization curves of GL-MoS 2 -CC/MFC, GL-MoS 2 -SSFF/MFC, CC/MFC, and SSFF/MFC. [Display omitted] • One-step hydrothermal method was proposed to synthesize graphene-like MoS 2 nanoflowers. • Graphene-like MoS 2 nanoflowers were used to modify microbial fuel cell anodes. • The method and the nanoflowers modification were proved to be simple, effective and of low cost. Anode, usually with limited specific surface area, poor biocompatibility and high-cost materials, is still the key obstacle for conventional dual-chamber microbial fuel cell (MFC)'s wide application. To combat this challenge, graphene-like molybdenum disulfide (GL-MoS 2) nanoflowers with a lateral size 200–300 nm are successfully synthesized via a simple one-step hydrothermal method and are used to modify MFC anodes. The experimental results show that GL-MoS 2 nanoflowers modified carbon cloth (CC) and stainless-steel fiber felt (SSFF) anode obtains their maximum power density of 960.4 mW·m−2 and 713.6 mW·m−2 which are 1.7 and 3.6 times of their unmodified counterparts, respectively, which indicates that the modification not only can offer large specific surface area and good biocompatibility for biofilm growth, but also makes the anode surface more accessible for microbes' colonization and substrate transfer and thus reduces polarization loss considerably. The graphene-like materials, especially those like GL-MoS 2 , are promising materials for excellent and cost-effective anode modification. [ABSTRACT FROM AUTHOR]

By combining two different types of layered nanofillers and making full use of synergistic effects, the frictional properties of the coating can be further improved. In this study, GO-MXene composites with "sandwich" structures were successfully prepared. Compared with pure PI, the tensile modulus of PI/GO-MXene composite coating is increased by 18.45 %, the tensile strength is increased by 54.49 %, the wear rate is reduced by 91.6 %, and the coefficient of friction is reduced by 34.4%. This is mainly due to the "bridging effect" of the polydopamine (PDA) to form the GO-MXene-GO "sandwich" structure, which gives full play to the synergistic lubrication between GO and MXene. [Display omitted] • The sandwich structure GO-MXene composite fillers are prepared by PDA bridging. • GO and MXene synergistically improve the frictional properties of PI composites. • Compared with pure PI, the COF of PI/GO-MXene composite is reduced by 34.4 %. • Compared to pure PI, the wear rate of PI/GO-MXene composite is reduced by 91.6 %. [ABSTRACT FROM AUTHOR]

The achievement of oil/water separation, characterised by easy operation, low cost and low energy consumption, significantly impacts environmental protection and economic loss reduction. However, industry practitioners still face a considerable challenge. In this study, we reported an efficient, recyclable and environmentally friendly material that facilitates the rapid separation of oil slicks from water surfaces. This material, known as magnetorheological (MR) fluid, demonstrates promising capabilities. The manganese ferrite (MnFe 2 O 4) nanospheres were synthesised through a simple solvothermal method, employing oleic acid for hydrophobic modification. The resulting MnFe 2 O 4 nanospheres exhibited a hierarchical morphology, rough surface, well-defined mesostructure, high saturation magnetisation and superparamagnetic characteristics. These unique properties make the MnFe 2 O 4 nanospheres suitable for incorporation into MR fluid and effective oil removal. The MnFe 2 O 4 nanospheres-based MR fluid demonstrated magnetic field-dependent rheological properties, excellent sedimentation stability, remarkable oil-removal efficiency and favourable recycling performance. Thus, the developed MnFe 2 O 4 nanospheres-based MR fluid can serve as an effective tool for removing oil slicks from water surfaces. [ABSTRACT FROM AUTHOR]

Graphical abstract Oxygen vacancies along with Sn were introduced into hematite nanorod arrays via using graphite plate as a supporting plate. Highlights • A local reducing atmosphere was created via partial oxidation of graphite. • Oxygen vacancies were introduced into hematite. • The photocurrent density of Fe 2 O 3 increases by 70% via introducing oxygen vacancies. • Oxygen vacancies promote the charge separation and transport of hematite. • The donor density of Fe 2 O 3 increases by 73% in the presence of oxygen vacancies. Abstract Sn Doping and creation of oxygen vacancies have been adopted universally to overcome the poor electric conductivity and unfavorable hole diffusion length of α-Fe 2 O 3 photoanodes. Generally, Sn doping is realized via longitudinal migration of tin element from FTO (fluorine-doped tin oxide) substrates into α-Fe 2 O 3 at high temperature. To introduce oxygen vacancies along with Sn into hematite for further promoting its electric conductivity, we have created a local reducing atmosphere via partial oxidation of graphite while doping hematite with Sn. The donor density of the resultant Fe 2 O 3 photoanode annealed on graphite (G-Fe 2 O 3) at 770 °C for 20 min is increased to ∼1.7 times that of the counterpart annealed on SiO 2 powders (S-Fe 2 O 3), indicating that the electric conductivity of hematite is improved after introduction of oxygen vacancies. Moreover, oxygen vacancies have been demonstrated to significantly reduce the charge transfer resistance of Sn doped hematite. Consequently, the photocurrent density of G-Fe 2 O 3 is enhanced remarkably (∼70%) compared with S-Fe 2 O 3. However, the improvement in photocurrent density due to oxygen vacancies becomes less significant when more Sn is doped into hematite. The strategy for creation of oxygen vacancies reported here can be extended to other photoanodes for better understanding the effect of oxygen vacancies on PEC performance. [ABSTRACT FROM AUTHOR]

Super-capacitor (SC) activated-carbon (AC) carbon-nanotubes (CNTs) (SC-AC-CNTs) is a kind of AC-based composite material and it combines the advantages of carbon nanotubes and activated carbon, including a series of peculiar properties such as low charge transmission resistance, super large specific area and excellent power characteristic. In this study, SC-AC-CNTs are first used to modify the carbon cloth (CC) anodes of microbial fuel cells (MFCs) and compared with that of SC-AC and CC. The measurements show that the specific surface area is increased from 219.519 m 2 g −1 to 283.643 m 2 g −1 after modification. The new anode is assembled in a urine-powered MFC (UMFC) to test its effectiveness. It is found that the amount of microorganisms attached on the new anode is much larger than that on the blank anode in UMFC. The maximum power densities of the UMFC assembled with SC-AC-CNTs and SC-AC modified anodes are 899.52 mW m −2 and 555.10 mW m −2 , which are 2.9 and 1.8 times of that of the blank UMFC, respectively. The tests also shows that the UMFC with SC-AC-CNTs-modified anode creates a much longer duration of 105 h at high-voltage plateau in a single cycle that is about 2–3 times of the other two groups. These findings demonstrate that these two double layer capacitor materials can effectively boost overall MFC performance. [ABSTRACT FROM AUTHOR]

Abstract Electrospinning is firstly used to one-pot synthesis of Li 3 VO 4 @C nanofibers in a large scale. Although with the presence of organic sources in synthesis process, the pure phase Li 3 VO 4 with superior nanofibrous morphology is still successfully obtained through adjusting different heat treatment processes and different vanadium sources. The prepared Li 3 VO 4 @C nanofibers exhibit a unique structure in which nanosized Li 3 VO 4 particles are uniformly embedded in amorphous carbon matrix. Compared with Li 3 VO 4 /C powder, Li 3 VO 4 @C nanofibers display enhanced reversible capacity of 451 mAh g−1 at 40 mA g−1 with an increased initial coulombic efficiency of 82.3%, and the capacity can remain at 394 mAh g−1 after 100 cycles. This superior electrochemical performance can be attributed to its unique structure which ensures a high reactivity by nanosized Li 3 VO 4 , more stable electrode/electrolyte interface by carbon encapsulation, improved electronic conductivity and buffered volume changes by flexible carbon matrix. The electrospinning technology provides an effective method to obtain high performance Li 3 VO 4 as a promising anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Hollow mesoporous PPy@MnO 2 composites were successfully synthesized by a low-temperature redox reaction. The synthesized hollow mesoporous PPy@MnO 2 electrode has outstanding electrochemical properties with a specific capacitance of 713 F g−1 at 1 A/g and a 92% retention rate after 5000 cycles at 4 A/g. The asymmetric supercapacitor constructed using PPy@MnO 2 as the positive electrode material achieved a high energy density of 40.8 Wh kg−1 at a power density of 720 W kg−1, and the capacitance retention rate can be maintained at 90.5% after 5000 charge/discharge cycles at 5 A/g. [Display omitted] • Hollow mesoporous PPy@MnO 2 composite were successfully synthesized by a low-temperature redox reaction. • PPy@MnO 2 composite with hollow mesoporous core–shell structure had good performance in supercapacitor. • The asymmetric supercapacitor devices assembled with PPy@MnO 2 composite possess remarkable cycling stability (90.5 % after 5000 cycles at 5 A g−1) and high energy density (40.8 Wh kg−1 at the power density of 720 W kg−1). In this work, hollow mesoporous PPy microspheres were prepared by using mesoporous SiO 2 as a hard template, and hollow mesoporous PPy@MnO 2 composites were successfully synthesized by a low-temperature redox reaction. The unique heterogeneous structure can realize the complementary advantages of the two materials. PPy can be used as a template to support the whole structure, and the design of the hollow structure will further buffer the volume change during cycling. In addition, the mesoporous structure will further increase its specific surface area and porosity, thereby enhancing the stability of its overall structure and internal electron transport, and significantly increasing the number of active sites. Thus, the synthesized hollow mesoporous PPy@MnO 2 electrode has outstanding electrochemical properties with a specific capacitance of 713 F g−1 at 1 A g−1 and a 92 % retention rate after 5000 cycles at 4 A g−1. The asymmetric supercapacitor constructed using PPy@MnO 2 as the positive electrode material achieved a high energy density of 40.8 Wh kg−1 at a power density of 720 W kg−1. This work inspires a simple idea for designing hollow mesoporous nanocomposite electrodes with excellent electrochemical performance and provides a high-performance supercapacitor material for its practical applications. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 @PPy@MnO 2 ternary core-shell nanospheres are synthesized by facile solvothermal, in-situ polymerization, and redox reactions.The nanocomposite exhibits excellent electrochemical performance with specific capacitance of 751F g−1 at 1 A/g and remarkable cycling stability (87.0% capacitance retention after 5000 cycles at 4 A/g). The asymmetric supercapacitor devices assembled with Fe 3 O 4 @PPy@MnO 2 nanocomosite possess remarkable cycling stability (95.2% after 5000 cycles at 5 A/g) and high energy density (71.3 Wh kg−1 at the power density of 750 W kg−1). [Display omitted] • Fe 3 O 4 @PPy@MnO 2 ternary core-shell nanospheres are synthesized. • The electrode exhibits high specific capacitance and good cycling stability. • The asymmetric supercapacitor devices possess high energy density. The rapid development of supercapacitors has led to increasing demand for electrode materials with excellent electrochemical properties. In this study, Fe 3 O 4 @PPy@MnO 2 nanocomposites with porous core and double-shell layers were successfully synthesized and utilized as supercapacitor electrode materials. Specifically, a dense PPy coating is formed on the porous Fe 3 O 4 surface to ensure high structural stability, and a MnO 2 shell layer could be easily introduced on the PPy surface through the redox reaction between PPy and KMnO 4. The prepared composite electrode material has the advantages of high specific surface area, short diffusion distance of electrolyte ions, good electron transfer, and fast and reversible Faraday reaction. The Fe 3 O 4 @PPy@MnO 2 electrode not only exhibits high specific capacitance (751F g−1 at 1 A/g), but also exhibits excellent cycling stability (87.0 % capacitance retention after 5000 cycles at 4 A/g). This is owing to the synergistic effect of the porous Fe 3 O 4 core, the dense PPy coating, and the MnO 2 nanosheet shell. Furthermore, the asymmetric supercapacitor devices assembled with Fe 3 O 4 @PPy@MnO 2 nanocomosite possess remarkable cycling stability (95.2 % after 5000 cycles at 5 A/g) and high energy density (71.3 Wh kg−1 at the power density of 750 W kg−1). These results demonstrate the great potential of Fe 3 O 4 @PPy@MnO 2 nanocomposites with porous cores and double shells as electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

In the backdrop of the carbon neutrality, lithium-ion batteries are being extensively employed in electric vehicles (EVs) and energy storage stations (ESSs). Extremely harsh conditions, such as vehicle to grid (V2G), peak-valley regulation and frequency regulation, seriously accelerate the life degradation. Consequently, developing long-life batteries for typical scenarios has emerged as a crucial focus for future endeavors. This paper concentrates on the fundamental scientific inquiries and comprehensively reviews aspects including the urgent requirements, degradation mechanisms, design methods, durability modeling and management approaches for long-life batteries. Firstly, it underscores the significance and urgency of developing long-life batteries under the typical EV and ESS scenarios. Subsequently, we delve into the long-life battery design methods concerning degradation mechanism suppression. Following this, the degradation modeling and advanced management strategies for achieving long-life batteries are elucidated. Lastly, facing the existing challenges and future opportunities, we provide new insights and perspectives to promote the development and practical application of long-life lithium-ion batteries. • A comprehensive review of the key issues towards long-life battery is presented. • The pressing long-life demands of EV and ESS typical application is highlighted. • A critical review of degradation mechanism and modeling is emphasized. • Challenges and solutions of long-life battery design and management are discussed. • Prospects of long-life battery are illustrated. [ABSTRACT FROM AUTHOR]

In this paper, one-dimensional porous Co 3 O 4 nanobelts were synthesized via a facile template-free hydrothermal method and subsequent the thermal decomposition. Their microstructures and morphologies were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and N 2 adsorption–desorption techniques. The results indicate that the reaction parameters such as the molar ratio of Co(NO 3 ) 2 ·6H 2 O to C 2 H 4 N 4 , the amount of Co(NO 3 ) 2 ·6H 2 O, the hydrothermal temperature and time play crucial rules in controlling the microstructures and morphologies of the as-prepared cobalt precursors. A possible formation mechanism was proposed. Moreover, the obtained porous Co 3 O 4 nanobelts exhibit ethanol gas sensing properties superior to the commercial Co 3 O 4 powders at a working temperature of 200 °C, suggesting their potential applications as nanosensors. [ABSTRACT FROM AUTHOR]

Fe-based oxide electrodes for practical applications in supercapacitors (SCs) suffer from low conductivity and poor structural stability. To settle these issues, we report on the design and synthesis of Fe 3 O 4 /carbon nanocomposites via firmly anchoring mesoporous Fe 3 O 4 nanospheres onto N-doped carbon nanotubes (N-CNTs) via C–O–Fe bonds. Mesoporous Fe 3 O 4 nanospheres are featured by rich electroactive sites and short ion diffusion pathways. The N-CNTs, on the other hand, serve as the scaffolds, which not only provide conductive networks but also suppress the accumulation between mesoporous Fe 3 O 4 nanospheres as well as alleviate volume changes during charge/discharge cycles. Accordingly, the constructed Fe 3 O 4 /N-CNTs nanocomposite electrode demonstrates improved specific capacity values of up to 314 C g−1 at 1 A g−1, with 92% retention of the initial capacity after 5000 cycles at 10 A g−1. In addition, the assembled Fe 3 O 4 /N-CNTs//active carbon (AC) asymmetric supercapacitor (ASC) device possesses an energy density of 25.3 Wh kg−1, suggesting that the prepared Fe 3 O 4 /N-CNTs nanocomposites are promising electrode materials for use in SCs. [ABSTRACT FROM AUTHOR]

Power converters in the system-level real-time simulation are usually emulated by L/C-based associated discrete circuit (L/C-ADC). However, the L/C-ADC approaches may suffer from two issues: How to mitigate the unacceptable virtual power loss especially in high-frequency applications, and how to tune LC parameters setting which is affected by the external circuit. This paper proposes a novel generalized associated discrete circuit (G-ADC) model with parameterized history current sources. By utilizing the stability region of the feasible parameter space, the optimized G-ADC models with the best damping characteristic are developed for both two-level and three-level converters. The analytical results also guarantee that the parameters of the optimized G-ADC model are independent of the external circuit for most power grid applications. Furthermore, an field programmable gate array (FPGA)-based real-time simulation platform is built to verify the feasibility of the proposed scheme. Extensive simulation and hardware-in-loop experiment results demonstrate the effectiveness and superiority of best-damped models as well as the modeling flexibility corresponding to insensitivity to operating conditions and external system parameters. [ABSTRACT FROM AUTHOR]

Hydrogel actuators with fast responsive speed, large driving power, diverse motions, superior mechanical properties and good environmental adaptability could be a suitable candidate for complex-task scenarios. However, a complete aggregation of these above characteristics is rarely reported, due to limitations from processing methods, raw materials and structural configuration of present hydrogel actuators. Herein we designed and fabricated complex-chamber-structure hydrogel actuators basing on soft interfacial adhesion of aluminum hydroxide nanocomposite hydrogels without any mold, template and valuable equipment, demonstrating that this method possessed simple, facile and inexpensive features. These composite hydrogels showed high tensile (0.5–1.0 MPa) and compressive (2–15 MPa) resistance properties, much higher than those of previously reported fluid-driven hydrogel actuators, which meant that our hydrogel actuators could have a higher cargo loading capacity. The cavity-structure soft actuators owned superior sealability and self-recoverability, and could give rapid uniaxial expansion and multidirectional large-scale bending under fluid actuation. Furthermore, those actuators with sucker structure were able to transfer heavy objects (e.g. 80 g glass plate and 180 g billiard ball) from water to air, and also move a plastic plate from back to right in three-dimensional space, indicating that this complex-cavity hydrogel actuators could suit to multi-task scenarios. The exquisitely assembled process of intricate chamber structure will offer a novel approach for hydrogel actuators with diversified driving functions. [Display omitted] • Interfacial adhesion enables fabrication of various hydrogel actuators. • Cavity-type hydrogel actuators transfer heavier object than other hydrogel ones. • Multi-chamber hydrogel actuators exhibit multidirectional bending by fluid actuation. [ABSTRACT FROM AUTHOR]

The electromagnetic transient simulation of a power system with nonlinear characteristics is very time-consuming due to numerous inversion calculations of the admittance matrix. To speed up the simulation of the power system with nonlinear characteristics, a multi-rate and parallel electromagnetic transient simulation method is proposed. Firstly, a Multi-Area Thevenin Equivalents (MATE)-based parallel algorithm considering nonlinear characteristics of the power system is proposed. This method guarantees the admittance matrix is constant by considering changing branches as link current without dividing the subnet again. Secondly, considering the differences of the time constant of the AC/DC subnet, different simulation steps are used for these subnets. The Lagrange interpolation method is used for calculating the Thevenin voltage of the AC subnet in non-synchronous time. Calculation methods of the DC subnet Thevenin voltage is proposed by considering the simulation results during the entire large simulation step. Finally, the simulation process is optimized for improving the simulation efficiency further. The simulation results show that the proposed method could greatly improve the simulation efficiency without losing simulation accuracy too much compared with the traditional method. [ABSTRACT FROM AUTHOR]

Urine-powered microbial fuel cells (UMFCs) are bioelectrochemical system which can recover energy from urine–a typical wastewater produced in urban and aerospace ships. The anode is the key unit determining the UMFC performance. It is proposed in this paper to use three-dimensional printing (3DP) technology to fabricate 3D structure anodes which is advantageous for improving the performance. With the help of 3DP, any special anode design for a particular reactor could be manufactured, which can be difficult and even impossible for conventional methods Macro-porous 3D anodes of good electrochemical performance for UMFCs were fabricated by 3DP and polyaniline (PANI) surface modification. The surface of the anode materials is both hydrophilic and rough. The power densities of UMFCs equipped with PANI-modified 3DP anodes were 0.934 W m −3 and 0.798 W m −3 (per anode chamber volume) fabricated from two different mother materials. These findings demonstrate that macro-porous anode can be fabricated by 3DP and can practically operate UMFCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical structured MnFe 2 O 4 nanospheres were prepared through a solvothermal method. • Uniform particle size, mesoporous characteristic and superparamagnetic behavior. • A high performance magnetorheological fluid based on MnFe 2 O 4 nanospheres. • Typical magnetorheological effect and improved sedimentation stability were achieved. In this research, novel hierarchically structured cauliflower-shaped MnFe 2 O 4 nanospheres were synthesized via a simple solvothermal method and their potential application for high performance magnetorheological fluids was investigated. The samples were comprehensively characterized using FE-SEM, TEM, FTIR, XRD, BET, TGA, XPS and VSM. It was revealed that the prepared MnFe 2 O 4 nanospheres exhibited hierarchical cauliflower-like morphology and the average particle size was found to be 182 nm. More importantly, the MnFe 2 O 4 nanospheres demonstrated typical mesoporous structure, high specific surface area of 30.3 m2/g and moderate saturation magnetization of 29.3 emu/g, which were suitable for preparation of a uniform and stable MR suspension. The rheological performances comprising shear stress, viscosity, storage modulus and loss modulus of MR fluid under different external magnetic fields were measured using a dynamic rotational rheometer. The results indicated that the MR fluid possessed enhanced MR responses as the magnetic field intensity increased, which were attributed to the rapid formation of robust chain-like structures composed of MnFe 2 O 4 nanospheres inside the MR suspension. In addition, it was observed that the sedimentation stability of MR fluid containing MnFe 2 O 4 nanospheres was much more prominent than that of the suspension based on spherical carbonyl iron particles in the same testing period. [ABSTRACT FROM AUTHOR]

In this study, manganese ferrite/graphene oxide (MnFe 2 O 4 /GO) nanocomposites as controlled targeted drug delivery were prepared by a facile sonochemical method. It was found that GO nanosheets were fully exfoliated and decorated with MnFe 2 O 4 nanoparticles having diameters of 5–13 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of the obtained MnFe 2 O 4 /GO with saturation magnetization of 34.9 emu/g at room temperature. The in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared MnFe 2 O 4 /GO even at the concentration as high as 150 μg/mL. Doxorubicin hydrochloride (DOX) as an anti-tumor model drug was utilized to explore the application potential of MnFe 2 O 4 /GO for controlled drug delivery. The drug loading capacity of this nanocarrier was as high as 0.97 mg/mg and the drug release behavior showed a sustained and pH-responsive way. [ABSTRACT FROM AUTHOR]

In this study, monodisperse cobalt ferrite (CoFe 2 O 4 ) nanoparticles were prepared successfully with various additions of polyvinylpyrrolidone (PVP) by sonochemical method, in which PVP served as a stabilizer and dispersant. The effects and roles of PVP on the morphology, microstructure and magnetic properties of the obtained CoFe 2 O 4 were investigated in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID). It was found that PVP-coated CoFe 2 O 4 showed relatively well dispersion with narrow size distribution. The field-dependent magnetization curves indicated superparamagnetic behavior of PVP-coated CoFe 2 O 4 with moderate saturation magnetization and hydrophilic character at room temperature. More importantly, the in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared PVP-CoFe 2 O 4 even at the concentration as high as 150 μg/mL after 24 h treatment. Considering the superparamagnetic properties, hydrophilic character and negligible cytotoxicity, the monodisperse CoFe 2 O 4 nanoparticles hold great potential in a variety of biomedical applications. [ABSTRACT FROM AUTHOR]

In this study, cobalt ferrite/graphene oxide (CoFe 2 O 4 /GO) nanocomposites were synthesized successfully by a facile sonochemical method. The microstructure and physical properties of CoFe 2 O 4 /GO nanocomposites were investigated in detail by TEM, XRD and SQUID. It was found that GO nanosheets were fully exfoliated and decorated homogeneously with CoFe 2 O 4 nanoparticles having diameters of 8∼15 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of as-prepared CoFe 2 O 4 /GO with saturation magnetization ( M s ) of 34.9 emu/g at room temperature. The ferrofluid was prepared by the obtained CoFe 2 O 4 /GO with 25 wt% particles and its magnetorheological (MR) properties were tested using a Physica MCR301 rheometer fitted with a magneto-rheological module. The CoFe 2 O 4 /GO-based ferrofluid exhibited typical MR effect with increasing viscosity, shear stress and yield stress depending on the applied magnetic field strength. [ABSTRACT FROM AUTHOR]

• An optimization method is employed to design side plates for a battery module. • Thermal safety and energy density of a battery module are effectively improved. • Average thermal runaway propagation time interval is prolonged by 46.0%. • Lightweight of a battery module with side plates fulfilled with a 59.6% mass decrease. • Effect of aggravating heat transfer through side plates is significantly weakened. Thermal runaway propagation in battery systems seriously hinders the rapid development of electric vehicles. Side plates are commonly employed to ensure the rigidity of the battery system, which can considerably affect the propagation behaviors. However, little attention has been focused on optimizing the design of side plates to mitigate the failure propagation from the perspective of weakening heat transfer. In this study, an orthogonal experimental design was applied to investigate the effects of the thickness, height and convective heat transfer coefficient of side plates, and the thickness of thermal insulating slices on regulating propagation behaviors. The results show that the height of the side plates is the most significant factor in the propagation process. Furthermore, a multi-objective optimization method based on a verified approximate model was proposed to design lightweight side plates with thermal safety. The Pareto frontier among the optimal objectives was obtained by using Non-dominated Sorting Genetic Algorithm II. The average propagation time interval is effectively prolonged by 46.0% after multi-objective optimization. Moreover, the mass of the side plates is decreased by 59.6%, resulting in a lightweight battery module. The local hot pot (battery failure point) first reaching the triggering temperature of the thermal runaway moves from both sides of the battery module to the center of the batteries. This study creatively presents the multi-objective optimization of side plates in a battery module to mitigate thermal runaway propagation. The results can provide valuable guidelines for the safety design of battery modules. [ABSTRACT FROM AUTHOR]

Three-dimensional hierarchical Co 3 O 4 peony-like microspheres have been successfully synthesized via a facile ethylene glycol mediated solvothermal method combined with a subsequent calcination. The as-prepared peony-like microspheres are assembled by many intercrossed nanosheets with a thickness of 30 nm. The reaction conditions such as the amount of hexadecyl trimethyl ammonium bromide and sodium acetate as well as the solvothermal time are investigated to explore the effects on the morphology of the final Co 3 O 4 products. According to these experiment results, a possible formation mechanism of the peony-like microspheres is proposed. Furthermore, when evaluated as anode materials for lithium storage, the Co 3 O 4 peony-like microspheres exhibit high lithium storage capacity and good cycling performance, having a discharge capacity of 975 mA h g −1 at 100 mAg −1 after 50 cycles. [ABSTRACT FROM AUTHOR]

In this work, three-dimensional hierarchical ZnCo 2 O 4 flower-like microspheres have been synthesized on a large scale via a facile and economical citrate-mediated hydrothermal method followed by an annealing process in air. The as-synthesized ZnCo 2 O 4 flower-like microspheres are constructed by numerous interweaving porous nanosheets. According to the experimental results, a formation mechanism involving the assembly of the nanosheets from nanoparticles into flower-like microsphere is proposed. As a virtue of their beneficial structural features, the ZnCo 2 O 4 flower-like microspheres exhibit a high lithium storage capacity and excellent cycling stability (1136 mA h g −1 at 100 mA g −1 after 50 cycles). This remarkable electrochemical performance can be ascribed to the hierarchical structure and porous structures in the nanosheets, which effectively increases the contact area between the active materials and the electrolyte, shortening the Li + diffusion pathway and buffering the volume variation during cycling. [ABSTRACT FROM AUTHOR]

Flat polyimide (PI) film and silicon dioxide nanoparticle-textured PI film were prepared by means of the spin-coating technique. The adhesion and friction properties of the flat PI surface and nano-textured PI surface were investigated by a series of Atomic force microscope (AFM) colloidal probes. Experimental results revealed that the nano-textured PI surface can significantly reduce the adhesive force and friction force, compared with the flat PI surface. The main reason is that the nano-textures can reduce the contact area between the sample surface and colloidal probe. The effect of colloidal probe size on the friction behavior of the flat and nano-textured PI surfaces was evaluated. The adhesive force and friction force of nano-textured PI surface were increased with the increasing of the size of interacting pairs (AFM colloidal probe) due to the increased contact area. Moreover, the friction forces of flat and nano-textured PI surfaces were increased with applied load and sliding velocity. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are suffering from severe thermal runaway risks in the use of their whole lifespans. The heat release characteristics of thermal runaway after fast charging have been proven to be highly related to lithium plating, yet whose impacts on the eruption behaviors are rarely investigated. In this study, the changes in the battery eruption temperature during thermal runaway after fast charging are thoroughly analyzed, and the effects of lithium plating on gas production are revealed. Accelerating Rate Calorimetry tests of pouch cells and prismatic cells are performed to investigate the eruption temperature of LIBs charged at different rates, confirming the advanced eruption of thermal runaway on batteries with plated lithium. To reveal the root cause of early eruptions, reactions between plated lithium and electrolytes are characterized by Synchronous Thermogravimetry Analysis and Mass Spectrometry, observing the fierce gas production process. Afterwards, and the gas and solid products of the reaction are further obtained using partially reactive systems in hot-box tests, and their compositions are analyzed. Overall, this study contributes to a more profound understanding of the characteristics of thermal runaway after fast charging, providing valuable insights on the rational design and management for LIB safety. • Battery eruption temperature in thermal runaway are decreased after fast charging. • The advanced eruption is caused by reaction between plated lithium and electrolyte. • The gas and solid products of the reaction are obtained to characterize safety risk. [ABSTRACT FROM AUTHOR]

In this paper, the ferric hydroxide colloid was prepared firstly, which was found suitable for the stabilizer of Pickering emulsion because of proper hydrophilicity. Then, molecularly imprinted polymers (MIPs) microspheres were synthesized by means of facile Pickering emulsion polymerization using ferric hydroxide colloid as emulsifier. In the synthesis process, hydrophilic methacrylic acid was used for the functional monomer, and ethylene glycol dimethacrylate served as the crosslinking agent. Bisphenol A (BPA), a typical endocrine-disrupting chemical, was used for the template molecules. The whole synthesis was based on the hydrogen bonds interaction between the functional monomer and template molecule. The ferric hydroxide colloid could be removed from the surface of microspheres by gentle washing. The morphology of obtained MIPs microspheres were assessed through the optical microscope and field emission scanning electron microscope, respectively. The results suggested that the MIPs appeared the regular spherical form with relatively wide size distribution, whose diameter varied from 10 to 60 μm. The adsorptive property was studied detailedly through a series of rebinding experiments. The research showed that MIPs have fast binding kinetics, whose rebinding equilibrium in tested concentration could be achieved within 60 min, and the rebinding capacity in 0.3 mmol L−1 of BPA initial solution is 8.19 μmol g−1. Additionally, the binding capacities of MIPs were larger than that of non-imprinted polymers in the batch equilibrium binding experiments. The binding selectivity was investigated with 4, 4′-biphenol and hydroquinone, which played the role of the structurally similar compounds of template molecules. The result showed that the MIPs were highly selective for BPA, and the imprinting factor was calculated to be 1.63. Reusability experiment indicates that our prepared MIPs have good mechanical stability and could be reused at least 5 times. The MIPs microspheres would be valuable in the field of environmental protection. [Display omitted] • Ferric hydroxide colloid is used as stabilizer of Pickering emulsion polymerization. • The obtained MIPs microspheres exhibit regular spherical form with clean surface. • MIPs display excellent binding capacities and accurate recognition specificity. [ABSTRACT FROM AUTHOR]

Abstract: A series of nickel (II) complexes (L)NiCl2 (7–9) and (L)NiBr2 (10–12) were prepared by the reactions of the corresponding 2-carboxylate-6-iminopyridine ligands 1–6 with NiCl2 ·6H2O or (DME)NiBr2 (DME=1,2-dimethoxyethane), respectively. All the complexes were characterized by IR spectroscopy and elemental analysis. Solid-state structures of 7, 8, 10, 11 and 12 were determined by X-ray diffraction. In the cases of 7, 8 and 10, the ligands chelate with the nickel centers in tridentate fashion in which the carbonyl oxygen atoms coordinate with the metal centers, while the carbonyl oxygen atoms are free from coordinating with the nickel centers in 11 and 12. Upon activation with methylaluminoxane (MAO), these complexes are active for ethylene oligomerization (up to 7.97×105 g mol−1 (Ni) h−1 for 11 with 2 equivalents of PPh3 as auxiliary ligand) and/or polymerization (1.37×104 g mol−1 (Ni) h−1 for 9). The ethylene oligomerization activities of 7–12 were significantly improved in the presence of PPh3 as auxiliary ligands. The effects of the coordination environment and reaction conditions on the ethylene catalytic behaviors have been discussed. [Copyright &y& Elsevier]

In this paper, the magnetic molecularly imprinted polymers (M-MIPs) for bisphenol A were synthesized via facile one-step Pickering emulsion polymerization using Fe 3 O 4 nanoparticles as the only stabilizer. The synthesis was based on non-covalent molecular imprinting strategy and performed by thermally initiated radical polymerization. The morphology of M-MIPs microspheres was examined by the field emission scanning electron microscope. The result indicated that most of prepared M-MIPs microspheres appeared snowman-like shape instead of the regular spherical form. The binding performance of M-MIPs microspheres was researched through a batch of binding tests including binding kinetics and binding isotherm. M-MIPs could reach binding equilibrium within 60 min. The binding capacity of M-MIPs (16.20 μmol g−1) was higher than that of magnetic non-imprinted polymers (M-NIPs), whose binding capacity was 9.44 μmol g−1. The specific binding was also carried out with BPA and its structurally similar compounds. The result showed that the M-MIPs possessed high selectivity towards BPA with the imprinting factor of 1.69. The M-MIPs may be useful in the environmental and analytic fields. Novel snowman-like magnetic molecularly imprinted polymer microspheres were prepared through facile one-step Pickering emulsion polymerization combined with the jamming of Fe 3 O 4 nanoparticles at the droplet surfaces. [Display omitted] • Pickering emulsion polymerization is performed with Fe 3 O 4 as the only stabilizer. • Most of obtained M-MIPs microspheres exhibit snowman-like shape. • M-MIPs display excellent binding capacities and accurate recognition specificity. [ABSTRACT FROM AUTHOR]

A 3D macroporous stainless steel fiber felt (SSFF) is used as base material and a simple water bath method is adopted to directly load Pd nanocatalysts on SSFF to fabricate the air cathode of microbial fuel cells (MFCs). The optimum Pd loading is explored on the basis of the optimized PVP additive amount and reaction temperature. To attain a high ORR activity, a conductive carbon black filling layer is added into the 3D pores of Pd-SSFF. A series of physical and electrochemical tests are conducted to characterize the morphology, chemical composition and oxygen reduction activity and then the obtained cathodes are installed in MFCs for electricity production verification. The results show that the Pd-SSFF cathode at a Pd loading of 0.5 mg cm−2 (Pd-SSFF-0.5) achieves high output voltage and power density (492.65 mV, 390.79 mW m−2) which are comparable to the conventional Pt/C electrode (504.80 mV, 405.47 mW m−2). Furthermore, with Pd-SSFF-0.5 cathode the high-voltage platform duration of MFC in one operation cycle is 2.79 times of that of Pt/C electrode. Excellent mechanical properties (high pressure and corrosion tolerance), high electric energy output and simple fabrication prove it is an efficient strategy to improve the overall performance of MFCs using the obtained cathodes. • 3D macroporous SSFF is proposed as base material in air cathode. • Pd nanocatalysts is loaded directly on SSFF with the simple water bath method. • This loading method can replace the complex preparation process of powder catalysts. • Filling carbon black into the 3D pores of Pd-SSFF helps improving ORR performance. • Excellent mechanical properties and high electric output are achieved by Pd-SSFF cathodes. [ABSTRACT FROM AUTHOR]

In order to improve the simulation speed of the AC/DC hybrid grid, the inductance/capacitance (L/C) switch model for line-commutated converter of high-voltage direct current (LCC-HVDC) is presented in this study. The time domain modeling method is used to analyze the circuit of L/C switch model for the six-pulse system in LCC-HVDC in a switching period. A parameter setting method of L/C switch model is proposed considering the transient response, the steady state performance, switching losses and simulation error of the switch. The inductance/capacitance (L/C) switch model for LCC-HVDC has the advantage of keeping the admittance matrix unchanged regardless of the change of switching state, which improves the simulation efficiency. Finally, the validity of the parameter setting method is verified. Compared with the test results of PSCAD/EMTDC, the accuracy of the proposed LCC-HVDC simulation model is proved. The model is suitable for real-time or offline simulation of AC/DC hybrid grid. [ABSTRACT FROM AUTHOR]