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To clarify the anodic dissolution mechanism of Mg, the hydrogen evolution from pure Mg in acidic solutions under galvanostatic conditions were systematically measured. With increasing anodic current density, the cathodic hydrogen evolution rate decreased, and the anodic hydrogen evolution became faster while some surface area on the Mg was becoming dark under anodic polarization. Based on the surface analysis results and the generally accepted basic electrochemical equations, the evolution kinetics of hydrogen from Mg was deduced, and the most possible surface intermediate active species that could facilitate the anodic Mg dissolution and anodic hydrogen evolution were proposed. This paper further develops the model of incomplete film Mg+ dissolution, explains many reported experimental phenomena, and clarifies misunderstandings of current mechanism.

Emerging contaminants (ECs) are widely distributed and potentially hazardous to human health and the ecological system. However, traditional wastewater treatment techniques are not sufficient to remove ECs. Magnetic nanomaterials are made of ferromagnetic or superparamagnetic magnetic elements such as iron and nickel, which can be easily separated from the aqueous solution, making them ideal adsorbents for contaminants in water. This review focused on the synthesis approaches of magnetic Fe3O4 nanoparticles (MFNs), as well as surface modification in order to improve their stability and functional diversity. Also, a detailed summary on the state-of-art application of magnetic nanomaterials on the removal of ECs was addressed. Additionally, challenges and future prospective of applying magnetic nanomaterials into real-world cases were discussed, in which the green and simple synthesis and evaluation of the toxic effects of MFNs are still of great challenge. This work summarizes the recent progress of using magnetic nanomaterials as promising and powerful tools in the treatment of ECs-contaminated water, benefiting researchers interested in nanomaterials and environmental studies.

In recent years, great progress has been made in integration of optoelectronic materials and fabrication technologies to improve the performance and simplify the device architecture. For next-generation optoelectronic applications, fibers are promising candidates for constructing diverse flexible and miniature electronics/optoelectronics. Recent advances of flexible fibers in integrating the functional materials with diverse optoelectronic properties open up the potential for advanced optical probes, functional surfaces, and smart textiles. In this paper, we highlight the recent advances of optoelectronic functional fibers in material selection, especially of organic materials, fabrication approaches, as well as their applications in energy conversion, photoelectric sensing, and logical response. We conclude by pointing out the challenges and future research direction in this area.

Yolk@shell mesoporous nanoparticles have received close attention due to their controllable structures and integrated functions. However, most yolk@shell nanosystems lack self-propulsion. Herein, yolk@spiky-shell structured carbon@silica nanomotors are fabricated with near-infrared (NIR) light self-thermophoretic propulsion as lipase nanocarriers for fuel-free triglyceride degradation. The light propulsion accelerates the accumulation of nanomotors on the droplet interface, and the efficient lipase loading further facilitates the rapid degradation of tributyrin droplets. By adjusting the yolk and spiky structure, the obtained semi-yolk@spiky-shell structured nanomotors exhibit the highest capacity of lipase (442 mg/g) and the highest light-driven diffusion coefficient (ca. 55% increase under 2 W/cm2 irradiation), thus improving the degradation efficiency of triglyceride (93.1% under NIR light vs. 66.7% without NIR light within 20 min). This work paves the way to rationally design yolk@shell structured nanomotors for diverse applications.

Acellular tissue matrix scaffolds are much closer to tissue’s complex natural structure and biological characteristics, thus assess great advantages in cartilage engineering. We used rabbit costal cartilage to prepare acellular microfilaments and further 3D porous acellular cartilage scaffold via crosslinking. Poly( l -lysine)/hyaluronic acid (PLL/HA) multilayer film was then built up onto the surface of the resulting porous scaffold. Furthermore, TGF-β3 was loaded into the PLL/HA multilayer film coated scaffold to obtain a 3D porous acellular cartilage scaffold with sustained releasing of TGF-β3 up to 60 days. The success of this project will provide a new way for the treatment of articular cartilage defects. Meanwhile, the anchoring and on-site sustained releasing of growth factors mediated by polyelectrolyte multilayered film can also provide a new method for improving the biocompatibility and the biofunctionality for other implanted biomaterials.

Summary The aprotic Li-CO2 battery with high energy density is an attractive energy-storage technology. However, its development is largely impeded by the sluggish kinetics of CO2 reduction and evolution reactions. Here, we demonstrate a class of ultrathin triangular RuRh alloy nanosheets as an exceptionally active catalyst for greatly accelerating the kinetics of CO2 reduction and evolution reactions and achieving a high-performance Li-CO2 battery. The RuRh alloy nanosheets-based battery can achieve the lowest voltage gap of 1.35 V during the charge-discharge process and stably cycle for 180 cycles with a cutoff capacity of 1,000 mAh g−1 at 1,000 mA g−1. Density functional theory calculations demonstrate the pivotal roles of Rh introduction in RuRh alloy nanosheets, which evidently activate the electron-transfer ability of surface Ru and balance the CO2 binding near Ru sites. We find that the d-d correlation between Rh and Ru contributes to the energetically favorable cycle of the Li-CO2 battery.

The stringent safety and sustainability requirements for electrolytes used in lithium batteries have led to significant research efforts into alternative materials. Here, a quasi-solid electrolyte based on biodegradable bacterial cellulose (BC) was successfully synthesized via a simple ball milling method. The BC provides plenty of sites for the attachment of ionic liquid electrolytes (ILEs) as well as ion transport channels. Moreover, the O-H groups contained in the BC molecular chains interact with anions in ILEs to form hydrogen bonds, which promotes the dissociation of the lithium salts. The prepared electrolytes (BC-ILEs) have good thermal stability with a decomposition temperature exceeding 300 °C and high ionic conductivities. The Li/BC-ILE/LiFePO

Lithium-air batteries are promising devices for electrochemical energy storage because of their ultrahigh energy density. However, it is still challenging to achieve practical Li-air batteries because of their severe capacity fading and poor rate capability. Electrolytes are the prime suspects for cell failure. In this Review, we focus on the opportunities and challenges of electrolytes for rechargeable Li-air batteries. A detailed summary of the reaction mechanisms, internal compositions, instability factors, selection criteria, and design ideas of the considered electrolytes is provided to obtain appropriate strategies to meet the battery requirements. In particular, ionic liquid (IL) electrolytes and solid-state electrolytes show exciting opportunities to control both the high energy density and safety.

Artificial micro/nanomotors with a dual-propulsion property have attracted considerable attention recently due to their attractive performances in complex fluidic environments. In this work, we successfully constructed Janus nanomotors with H2O2 and NIR light dual-propulsion by employing dendritic porous silica nanoparticles (DPSNs) as carriers via a Pickering emulsion and electrostatic self-assembly. The aminopropyl-modified DPSNs (DPSNs-NH2) with positive charge were semiburied in paraffin wax microparticles in order to achieve electrostatic adsorption of Pt nanoparticles (NPs) with negative charge on the exposed surface for H2O2 propulsion, followed by electrostatic adsorption of negatively charged CuS NPs with excellent NIR light absorption on the other exposed surface of the eluted DPSNs-NH2@Pt for NIR light propulsion. Center-radial large mesopores facilitate the high density loading of Pt NPs and CuS NPs for efficient propulsion. Compared with the commonly used sputtering approach, this Pickering emulsion method can realize relatively large-scale fabrication of Janus NPs. DPSNs-NH2@Pt@CuS Janus nanomotors can be effectively driven not only by self-diffusiophoresis, which results from the decomposition of H2O2 catalyzed by Pt NPs, but also by self-thermophoresis, which is generated from thermal gradients caused by the photothermal effect of CuS NPs. Moreover, the motion speed of the nanomotors can be conveniently modulated by regulating the H2O2 concentration and NIR light intensity. This work provides a novel exploration into the construction of dual-propulsion nanomotors, which are supposed to have significant potential in biomedical and intelligent device applications.

Hybrid micro/nanomotors with multiple distinct propulsion modes are expected to improve their motion ability in complex body fluids. Herein, we report a multi-stimuli propelled Janus lipase-modified dendritic silica/carbon@Pt (DMS/C@Pt) nanomotor with built-in engines for hybrid propulsions of H2O2, light, and enzyme. The enhanced motion of the DMS/C@Pt nanomotor is achieved under the stimulus of H2O2 that produces an oxygen concentration gradient derived from the asymmetric catalysis of Pt nanoparticles. Irradiated with near-infrared (NIR) light, the uneven photothermal effect of the carbon part propels this nanomotor by self-thermophoresis. Besides, lipase is efficiently loaded into the dendritic pores, which decomposes triglyceride on the silica part and induces self-diffusiophoretic propulsion. These multiple propulsions shed light on the rational integration of various functional building blocks into one micro/nanomotor for complex tasks in biomedical applications.

To achieve a long-cycle-life lithium-air battery, the catalyst, electrolyte and lithium anode should be optimized synergistically. Herein, we achieve a super-long cycle-life lithium-O2 battery by integrating the synergistic effect of highly active Pt3Co nanowires (PtCo NWs) cathode catalyst and stable quasi-solid SiO2-ionic liquid (IL) electrolyte. The PtCo NWs can effectively reduce the charge voltage below 3.2 V, but have to induce the decomposition of the conventional liquid electrolyte. The SiO2-IL electrolyte has a high ionic conductivity, but it still cannot match with carbonaceous oxygen electrode, due to its large charge overpotential. By combining the PtCo NWs cathode catalyst with quasi-solid electrolyte, the lithium-O2 battery can reversibly discharge and charge above 300 cycles (>3000 h). When the battery is disassembled, the lithium metal anode is preserved well, which is closely covered by a layer of SiO2 nanoparticles containing IL. By contrast, the lithium anode completely changes to the white powders for the one with ether-based electrolyte stored under the same condition, demonstrating the lithium anode is perfectly protected by the SiO2-IL electrolyte, which is a critical factor for achieving the long-life performance of lithium-O2 battery. Even under the air atmosphere, the battery can still cycle very well.

The oxygen evolution reaction (OER) is of prime importance in the development of highly efficient electrochemical energy conversion and storage technologies such as water splitting and zinc air batteries. Ru-based nanocatalysts are still the best catalytic system for the OER; however, one of the greatest challenges is their relatively poor stability for the OER. Here, we report a novel architecture of ultrathin RuRh@(RuRh)O2 core/shell nanosheets with a core of ultrathin metallic RuRh nanosheets and a shell of RuO2/RhO2 oxides as superb electrocatalysts toward the OER. The RuRh@(RuRh)O2 core/shell nanosheets can achieve a high electrocatalytic activity toward the OER, with a low 245 mV overpotential at 10 mA cm−2 and a Tafel slope of 51.2 mV dec−1, better than most state-of-the-art Ru-based or Ir-based electrocatalysts for the OER. Moreover, the RuO2/RhO2 oxides shell protect the normally labile RuRh NSs core against dissolution during the OER process, revealed by detailed rotating ring disk electrode (RRDE) measurements for simultaneously recording the dissolution of Ru on the ring electrode and the ex situ measurement of Ru dissolution using the galvanostatic method. Therefore, the RuRh@(RuRh)O2 core/shell nanosheets exhibit much better OER stability in acid media compared with RuRh nanosheets and commercial RuO2. Theoretical calculations reveal that once the formation of the surface oxidation layers is achieved, the O-sites evidentially crossover the Fermi level which could guarantee the high electroactivity towards adsorbates while the RuRh core serves as an electron reservoir with high electrical conductivity. The synergistic effect between the core and shell structure leads to the superior OER performance.

Poor interfacial contact and Li dendritic growth severely restrict practical applications of Li metal anodes. Herein, we report a novel biomimetic solid-state electrolyte based on injection of 1 M LiTFSI-Py13TFSI ionic liquid electrolyte into a leaf-like Al2O3 skeleton through an in situ sol–gel method. This structure is intended to address the poor contact at the interface and protect the Li metal anode. A large amount of ionic liquid electrolyte was absorbed by the leaf-like Al2O3 skeleton owing to its high specific surface area. This system improved the ionic conductivity and promoted migration of Li+ both in the bulk and at the interface. The lithiophilic Al2O3 skeleton was in close contact with metallic Li and formed a fast Li+ conductive layer (Li–Al–O composition), which facilitated uniform deposition of Li and thus inhibited Li dendrite formation during long-term cycling. Moreover, density functional theory calculations indicated spontaneous generation of a Li–Al–O layer and [Py13]+ in the ionic liquid facilitates this process. Symmetric Li cells assembled with this electrolyte exhibited an extremely long cycle lifetime of 1100 h at a high constant current density. This strategy of a biomimetic leaf-structured electrolyte with a Li–Al–O conductive layer at the interface addresses problems of solid-state Li metal batteries and provides an alternative system for practical applications.

Sodium-ion (Na-ion) hybrid capacitors as a novel electrochemical energy storage device have triggered considerable attention in recent years. However, the sluggish kinetics at anode and low specific capacity at cathode greatly hinder the overall performance output of Na-ion hybrid capacitors. Herein, we design a high-performance quasi-solid-state Na-ion hybrid capacitor assembled with the Mo2N quantum dots coupled carbon nanotubes as anode, decoupled hierarchical carbon nanotubes as cathode, and a porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane based gel electrolyte. For the anode, the uniformly dispersed Mo2N quantum dots offer abundant ion-accessible active sites and shortened ion diffusion path, which effectively accelerate Na ion storage kinetics. After decoupling and activation, the hierarchical carbon nanotubes with high specific surface area and numerous in-plane nanopores contribute to fast reversible anion adsorption and desorption, greatly boosting the specific capacity. Additionally, the low-tortuosity nanotubular electrode microstructure with open framework is conducive to unimpeded electrolyte ion permeation and thereby can maximize the utilization of active materials. Benefiting from the elaborate electrode architecture engineering and rational device configuration, the assembled quasi-solid-state Na-ion hybrid capacitor can achieve a high energy density of 100.6 Wh kg−1 at a power density of 117.5 W kg−1, which is among the best compared with other Na-ion hybrid capacitors. The demonstration of proof-of-concept of the quasi-solid-state Na-ion hybrid capacitors offers new insights into rational design of high-energy-density hybrid energy storage systems.

Mesoporous carbon nanoparticles (NPs) are widely used to construct nano-theranostic systems due to their excellent physicochemical properties. Herein, we introduce these mesoporous NPs as nanocarriers to build self-propelled transport systems. Such nanocarriers are successfully fabricated by depositing Pt NPs onto the half-sphere surface. Compared with conventional silica-based nanomotors, hollow mesoporous carbon nanospheres (HMCNs) based nanomotors can achieve a high loading efficiency (1370 mg/g) of anticancer drug doxorubicin hydrochloride (DOX) due to its hydrophobic nature. The enhanced motion is observed by introducing the NIR-light irradiation due to the local thermophoresis from the upward temperature of HMCNs and also observed by introducing H2O2 that drives the HMCNs@Pt by the asymmetric decomposition. Interestingly, such enhanced motion also results in the increase of the amount of HMCNs adhering to the surface of living cancer cells, which is beneficial for enhancing the efficiency of drug delivery. This synergetic carbon-based transport system with high cargo loading capacity and dual actuated autonomous motion ability displays immense potential for further functional “smart” devices.

To further improve the performance of accelerators, the first cryogenic normal-conducting RF gun in China was designed and manufactured. As a new and attractive trend, this optimized cryogenic RF gun can generate a low-emittance beam with a short-driven laser pulse because of its promising high gradient on the cathode. In this paper, optimization of the RF design and beam dynamics, including suppression of the peak RF field and elimination of the multipole mode, is presented. In addition, the emittance growth caused by the alignment deviation and RF jitter is discussed. After the gun was manufactured, a cold test was conducted at both room temperature and cryogenic conditions. At room temperature, the field distribution was obtained by the bead pull method. Under cryogenic conditions, the RF properties, such as the coupling coefficient and quality factor, varied with temperature. The test results agreed with the design. In the cryogenic test, vibration measurements were performed. Without vibration isolation, a maximum vibration of 50 $$\mu \text{m}$$ was observed. These cold test results are the basis of the following high-power test.

Using X-ray tomography, we experimentally investigate granular packings subject to mechanical tapping for three types of beads with different friction coefficients. We validate Edwards volume ensemble in these three-dimensional granular systems and establish a granular version of thermodynamic zeroth law. Within Edwards framework, we also explicitly clarify how friction influences granular statistical mechanics as modifying the density of states, which allows us to determine the entropy as a function of packing fraction and friction subsequently. Additionally, we obtain a granular jamming phase diagram based on geometric coordination number and packing fraction., 20 pages, 7 figures

There has been growing concern about the toxic effects of pollutants in the aquatic environment. In this study, a novel cell-based electrochemical sensor was developed to detect the toxicity of contaminants in water samples. A screen-printed carbon electrode, which was low-cost, energy-efficient, and disposable, was modified with tungsten disulfide nanosheets/hydroxylated multi-walled carbon nanotubes (WS2/MWCNTs-OH) to improve electrocatalytic performance and sensitivity. The surface morphology, structure, and electrochemical property of WS2/MWCNTs-OH composite film were characterized by emission scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, and electrochemical impedance spectroscopy. Grass carp kidney cell line was utilized as the sensor biorecognition element to determine the electrochemical signals and evaluate cell viability. The sensor was used to detect the toxicity of one typical contaminant (2,4,6-trichlorophenol) and two emerging contaminants (bisphenol AF and polystyrene nanoplastics). The 48 h half inhibitory concentration (IC50) values were 169.96 μM, 21.88 μM, and 123.01 μg mL−1, respectively, which were lower than those of conventional MTT assay, indicating the higher sensitivity of the proposed sensor. Furthermore, the practical application of the sensor was evaluated in chemical wastewater samples. This study provides an up-and-coming tool for environmental toxicity monitoring.

The corrosion resistance behavior of a highly dispersed MgO-MgAl2O4-ZrO2 composite refractory material is examined by testing with high-basicity and low-basicity RH (Ruhrstahl-Hereaeus) slags. The composite material exhibits greater resistance to the RH slags than the traditional MgO-Cr2O3 composite, MgO-ZrO2 composite, and MgO-MgAl2O4-ZrO2 composite. On the basis of the microstructural analysis and mechanisms calculations, the corrosion resistance behavior of the MgO-MgAl2O4-ZrO2 composite is attributable to its highly dispersed structure, which helps protect the high activity of ZrO2. When in contact with the slag, ZrO2 reacts with CaO to form the stable phase CaZrO3, which protects MgAl2O4 against corrosion, thereby enhancing the corrosion resistance of the composite.

Upgrading coal mine methane (CMM) with adsorption method is an effective way to enhance the energy utilizing efficiency and reduce greenhouse gas emissions. In this work, adsorption equilibrium and kinetics of CH4, N2 and O2, as typical components in CMM, on three carbon molecular sieves (CMSs) and the corresponding separation performances were studied. The equilibrium and kinetic selectivity were obtained from adsorption isotherms fitted with the Langmuir model and uptake curves fitted with the micropore-diffusion model, respectively. O2 with the highest diffusion time constant among three gases suggests the advantage of CMS-based kinetic separation in deoxygenation of CMM and the critical role that N2/CH4 kinetic separation plays in CH4 enrichment. CMS-1 with the highest microporosity has the largest adsorption capacities, and CMS-3 with a proper average pore size has the greatest N2/CH4 kinetic selectivity. The actual separation performances shown by CH4/N2/O2 breakthrough curves according to the principle for practical CMM upgrading processes exhibit the order of CMS-1 > CMS-3 > CMS-2 which is inconsistent with that of the conventional N2/CH4 selectivity highly due to the underestimation of effects of N2 equilibrium adsorption relative to N2 kinetic selection without covering specific adsorption range corresponding to practical working capacity region. A modified selectivity with consideration of actual N2 amount adsorbed was therefore developed, showing the correct performance order and the potential to be used as a practical adsorbent selection parameter. An advanced CMS materials design with proper existence of microporosity would benefit practical CMM upgrading in terms of reaching an optimal balance between adsorption equilibrium and kinetics.

Lithium metal is an ideal anode material for next-generation electrical energy storage because of its high specific capacity. However, uncontrolled growth of Li dendrites during deposition and stripping processes results in low coulombic efficiency and severe safety concerns. Here we report a porous and robust coating of metal-organic framework (MOF-199), which could physically suppress the growth of lithium dendrite by acting as a robust shield, and homogenize Li-ion concentration by its high-polarity structure, thereby relieving excess SEI formation. In addition, another MOF (ZIF-8) layer is also confirmed to effectively hinder the formation and penetration of Li dendrites. The MOF particle size in the coating layer is shown to be a key factor determining the level of protection. Finally, the ability of the MOF-199 layer to protect Na metal anodes is studied.

Flexible solid-state zinc-air batteries are promising energy technologies with low cost, superior performance and safety. However, flexible electrolytes are severely limited by their poor mechanical properties. Here, we introduce flexible bacterial cellulose (BC)/poly(vinyl alcohol) (PVA) composite hydrogel electrolytes (BPCE) based on bacterial cellulose (BC) microfibers and poly(vinyl alcohol) (PVA) by an in situ synthesis. Originating from the hydrogen bonds among BC microfibers and PVA matrix, these composites form load-bearing percolating dual network and their mechanical strength is increased 9 times (from 0.102 MPa of pristine PVA to 0.951 MPa of 6-BPCE). 6-BPCE shows extremely high ionic conductivities (80.8 mS cm-1). In addition, the solid-state zinc-air batteries can stably cycle over 440 h without large discharge and charge polarizations equipped with zinc anode and Co3O4@Ni cathode. Moreover, flexible solid-state zinc-air batteries can cycle well at any bending angle. As flexible electrolytes, they open up a new opportunity for the development of superior-performance, flexible, rechargeable, zinc-air batteries.

The removal characteristics of sub-25 nm ultrafine particles (UFPs) by different porous nanomaterials with different morphologies were studied based on efficiency curves obtained with specially designed filtration system. The material morphological effects on UFPs collection were investigated. The results demonstrate a complex and synergic mechanism of material structural framework, pore size distribution, and porosity order in terms of diffusion and interception dependent on flow velocity. Both porosity and fiber-like tubular structures promoted the UFPs removal. Microporosity and disordered mesoporosity could enhance the roughness of the internal surface and intensify the interaction with UFPs. Specifically, the large and ordered mesoporosity was able to render selectivity for UFPs at certain sizes and exhibited the best particle collection performance which can be largely associated with significant pore size and volume. The dependence of the ratio of diffusion to interception on flow velocity and the comparison of different pores in terms of the matching sizes with particles derived from single sphere efficiency model fitting results were also discussed. This work is significant to deeper understanding of interactions between airborne nanoparticles and porous surfaces.

An aprotic Li–O2 battery incorporating a conductive graphene interlayer displays an ultralow overpotential of 0.67 V and a stable cyclability over 200 cycles at a high current density of 500 mA g−1. The improved performance of the battery is attributed to the role of the graphene interlayer in boosting the formation and decomposition of discharge products.

Ag2Te nanowires with a diameter of approximately 200 nm and a length of several micrometers were prepared using a simple one-step solvothermal method without templates and surfactants. Ag(NO)3 and Na2TeO3 were used as the Ag and Te sources, respectively, and N2H4·H2O was used as the reducing agent. Based on the study of the morphology and composition of the Ag2Te nanowires obtained under different hydrothermal conditions, a possible formation mechanism of Ag2Te nanowires was proposed. An Ag-rich Ag2Te sample was prepared by adjusting the molar ratio of Ag and Te. Furthermore, Ag2Te nanowire powders were condensed to bulk materials by spark plasma sintering at 673 K for 5 min. The thermoelectric properties of the Ag2Te bulk materials were measured between 323 K and 673 K. The phase transition temperature of the transformation from α-Ag2Te to β-Ag2Te was determined to be 419 K by differential scanning calorimetry. The highest ZT values of pure Ag2Te and Ag self-doped Ag2Te bulk samples reached 0.9 and 1.1 at 623 K, respectively. These results indicate that this one-pot technique for preparing the Ag self-doped Ag2Te sample with enhanced thermoelectric performance may be widely used in other thermoelectric systems that can be fabricated by solution methods.

Despite various 2H-MoS2/carbon hybrid nanostructures have been constructed and committed to improve the performance for sodium-ion batteries (SIBs), they still show the limited cycle stability due to the relatively large volumetric expansion during the charge–discharge process. Herein, we report the construction of cobalt-doped few-layered 1T-MoS2 nanosheets embedded in N, S-doped carbon (CMS/NSC) nanobowls derived from metal-organic framework (MOF) precursor via a simple in situ sulfurization process. This unique hierarchical structure enables the uniformly dispersed Co-doped 1T-MoS2 nanosheets intimately couple with the highly conductive carbon nanobowls, thus efficiently preventing the aggregation. In particular, the Co-doping plays a crucial role in maintaining the integrity of structure for MoS2 during cycling tests, confirmed by first-principles calculations. Compared with pristine MoS2, the volume deformation of Co-doped MoS2 can be shrunk by a prominent value of 52% during cycling. Furthermore, the few-layered MoS2 nanosheets with 1T metallic phase endow higher conductivity, and thus can surpass its counterpart 2H semiconducting phase in battery performance. By virtue of the synergistic effect of stable structure, appropriate doping and high conductivity, the resulting CMS/NSC hybrid shows superior rate capability and cycle stability. The capacity of CMS/NSC can still be 235.9 mAh·g−1 even at 25 A·g−1, which is 51.3% of the capacity at 0.2 A·g−1. Moreover, the capacity can still remain 218.6 mAh·g−1 even over 8,240 cycles at 5 A·g−1 with a low decay of 0.0044% per cycle, one of the best performances among the reported MoS2-based anode materials for SIBs.

Modelling dynamic adsorption of sulfur dioxide (SO2) on activated carbons (ACs) is significant in guiding practical desulphurization processes and making highly efficient use of adsorbents in terms of the adsorption rate which largely depends on particle size. In this work, models derived from the Vermeulen and an improved linear driving force (LDF) rate equation were studied for the first time on SO2 adsorption over AC particles with different sizes. For larger particles (≥3 mm), breakthrough curves predicted by the Vermeulen equation showed good agreement with experimental data, demonstrating that intraparticle diffusion resistance varied with particle size, feed concentration, adsorption time and location. For smaller particles (1 mm), a correction on the volume-averaged adsorption capacity as a function of adsorption time and saturation in the rate equation was developed to avoid the underestimation of adsorption rate due to the inappropriate parabolic concentration profile inherent in the conventional LDF model. By providing a concentration gradient and adsorption rate closer to actual values, the improved LDF equation was confirmed to provide excellent prediction results on 1-mm particles. Different modelling characteristics of the two models indicates varying effects of intraparticle diffusion on adsorption rate with particle size regarding the specificity of SO2 physisorption on ACs.

The existing catalysts based on activated coke had generally poor denitration performance at low temperature, which could not meet the urgent needs of power plants and steel enterprises. In this study, activated coke loaded with FexCoyCezOm was prepared by incipient wetness impregnation method and employed to remove NOx at 100–350 °C in simulated flue gas. 3%Fe0.6Co0.2Ce0.2O1.57/AC catalyst exhibited highest NOx removal efficiency as it had more than 70%NOx conversion rate at 100 °C and achieved more than 90%denitrition efficiency at 250–350 °C. The catalyst also showed stable catalytic performance and good resistance to H2O or/and SO2 at 250 °C. Based on the results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), temperature programmed desorption (TPD), temperature programmed reduction (TPR) and Fourier transform infrared spectroscopy (FTIR), the enhanced performance could be attributed to the co-participation of Fe, Co and Ce species with different valence states, the high concentration of chemisorbed oxygen, highly dispersed active components, the increase of weak acid sites, good redox properties of metallic oxides and abundant founctional groups on the catalyts surface. Finally, the possible mechanism and kinetics of NOx removal over FexCoyCezOm/AC catalyst were discussed in detail, which revealed that the enhanced performance was resulted from the increased active sites and the redox cycle among Fe, Co and Ce.

As an advanced treatment method in the past five years, ultra-high dose rate (FLASH) radiotherapy as a breakthrough and milestone in radiotherapy development has been verified to be much less harmful to healthy tissues in different experiments. FLASH treatments require an instantaneous dose rate as high as hundreds of grays per second to complete the treatment in less than 100 ms. Current proton therapy facilities with the spread-out of the Bragg peak formed by different energy layers, to our knowledge, cannot easily achieve an adequate dose rate for FLASH treatments because the energy layer switch or gantry rotation of current facilities requires a few seconds, which is relatively long. A new design for a therapy facility based on a proton linear accelerator (linac) for FLASH treatment is proposed herein. It is designed under two criteria: no mechanical motion and no magnetic field variation. The new therapy facility can achieve an ultra-high dose rate of up to 300 Gy/s; however, it delivers an instantaneous dose of 30 Gy within 100 ms to complete a typical FLASH treatment. The design includes a compact proton linac with permanent magnets, a fast beam kicker in both azimuth and elevation angles, a fixed gantry with a static superconducting coil to steer proton bunches with all energy, a fast beam scanner using radio-frequency (RF) deflectors, and a fast low-level RF system. All relevant principles and conceptual proposals are presented herein.

Compared with a traditional optical system, the single-lens curved compound eye imaging system has superior optical performance, such as a large field of view (FOV), small size, and high portability. However, defocus and low resolution hinder the further development of single-lens curved compound eye imaging systems. In this study, the design of a nonuniform curved compound eye with multiple focal lengths was used to solve the defocus problem. A two-step gas-assisted process, which was combined with photolithography, soft photolithography, and ultraviolet curing, was proposed for fabricating the ommatidia with a large numerical aperture precisely. Ommatidia with high resolution were fabricated and arranged in five rings. Based on the imaging experimental results, it was demonstrated that the high-resolution and small-volume single-lens curved compound eye imaging system has significant advantages in large-field imaging and rapid recognition.

X-ray tomography study reveals that sheared granular mixtures with size difference segregate under convection and arching effects., Granular mixtures with size difference can segregate upon shaking or shear. However, the quantitative study of this process remains difficult because it can be influenced by many mechanisms. Conflicting results on similar experimental systems are frequently obtained when the experimental conditions are not well controlled, which is mainly due to the fact that many mechanisms can be at work simultaneously. Moreover, it is often that macroscopic or empirical measures, which lack microscopic physical bases, are used to explain the experimental findings and therefore cannot provide an accurate and complete depiction of the overall process. Here, we carry out a detailed and systematic microscopic structure and dynamics study of a cyclically sheared granular system with rigorously controlled experimental conditions. We find that both convection and arching effect play important roles in the segregation process in our system, and we can quantitatively identify their respective contributions.

Slot-die coating is generally regarded as the most effective large-scale methodology for the fabrication of organic solar cells (OSCs). However, the corresponding device performance significantly lags behind spin-coated devices. Herein, the active layer morphology, flexible substrate properties, and the processing temperature are optimized synergistically to obtain high power conversion efficiency (PCE) for both the flexible single cells and the modules. As a result, the 1 cm2 flexible devices produce an excellent PCE of 12.16% as compared to 12.37% for the spin-coated small-area (0.04 cm2 ) rigid devices. Likewise, for modules with an area of 25 cm2 , an extraordinary PCE of 10.09% is observed. Hence, efficiency losses associated with the upscaling are significantly reduced by the synergistic optimization. Moreover, after 1000 bending cycles at a bending radius of 10 mm, the flexible devices still produce over 99% of their initial PCE, whereas after being stored for over 6000 h in a glove box, the PCE reaches 103% of its initial value, indicating excellent device flexibility as well as superior shelf stability. These results, thus, are a promising confirmation the great potential for upscaling of large-area OSCs in the near future.

We perform combined X-ray tomography and shear force measurements on a cyclically sheared granular system with highly transient behaviors, and obtain the evolution of microscopic structures and the macroscopic shear force during the shear cycle. We explain the macroscopic behaviors of the system based on microscopic processes, including the particle level structural rearrangement and frictional contact variation. Specifically, we show how contact friction can induce large structural fluctuations and cause significant shear dilatancy effect for granular materials, and we also construct an empirical constitutive relationship for the macroscopic shear force., 26 pages, 4 figures

We report core@satellite Janus mesoporous silica-Pt@Au (JMPA) nanomotors with pH-responsive multi-phoretic propulsion. The JMPA nanomotors first undergo self-diffusiophoretic propulsion in 3.0 % H2 O2 due to the isolation of the Au nanoparticles (AuNPs) from the PtNPs layer. Then the weak acidity of H2 O2 can trigger the disassembly and reassembly of the AuNPs, resulting in the Janus distribution of large AuNPs aggregates. Such reconstruction of JMPA leads to the contact between PtNPs and AuNPs aggregates, thus changing the propulsion mechanism to self-electrophoresis. The asymmetric and aggregated AuNPs also enable the generation of a thermal gradient under laser irradiation, which propels the JMPA nanomotors by self-thermophoresis. Such multi-phoretic propulsion offers considerable promise for developing advanced nanomachines with a stimuli-responsive switch of propulsion modes in biomedical applications.

Efficient adsorbents for removal heavy metals are extensively urgent in modern society. Metal-organic frameworks (MOFs) with abundant porosity and tunable structure make it potential to access the advantages of high permeability and adsorbability in water pollutant control. However, MOFs nanoparticles inconvenient to recycle in solution hinder its application in water pollutant treatment. Herein, we report an in-situ growth and large-scalable manufacturing method to fabricate ZIF-8 nanoparticles on electrospun polyacrylonitrile (PAN) nanofibers membrane (ZIF-8/PAN NF) by hot pressing. Consequently, the prepared ZIF-8/PAN NF possesses high loading, uniform dispersion and large-scalable area as well as good flexibility. The fabricated ZIF-8/PAN NF exhibits excellent performance with fast flux (12,000 L/(m2h)) and high filtration efficiency (96.5%) for Cu2+ in dynamic adsorption. Additionally, adsorption and electrochemistry are introduced simultaneously. The Cu2+ removal rate of ZIF-8/PAN NF reaches 34.1% in 4 min with combination of adsorption and electrochemistry. While it is 29.2% for Cu2+ elimination in adsorption. Given the outstanding performance and easy manufacture, this study might bring MOFs powder to eliminate water pollution into practical application.

Traditional sacrificial anode Zn was intelligentized by Mg-alloying to automatically detect chloride contamination and smartly protect reinforcing steel. The intelligence of the Zn-Mg alloys was investigated in a simulated concrete pore solution (SCPS) contaminated by different concentrations of chloride. The results showed that the Zn-11Mg, Zn-32Mg, Zn-43Mg and Zn-66Mg were more sensitive to chloride contamination and could provide more sufficient current to protect the steel according to the corrosivity of the contaminated solution than the Zn, Zn-6Mg, Zn-19Mg and Mg. The corrosion resistance and the anodic behavior of these alloys coupled with the steel were systematically analyzed.

In this study, g-C3N4/NH2-MIL-88B(Fe) (MCN-x) heterostructures were successfully prepared using a facile solvothermal method. MCN-x composites exhibit excellent degradation performance toward ofloxacin in aqueous solution under visible light (λ > 420 nm). The photodegradation rate of ofloxacin by MCN-60 under visible light reaches 96.5% in 150 min, and the apparent first-order kinetics rate constant reaches 0.0217 min−1, 3.7 and 4.7 times that of pristine g-C3N4 and NH2-MIL-88(Fe), respectively. This decent photocatalytic performance is principally attributed that the introduction of g-C3N4 can notably promote the separation of photogenerated electron-hole pairs. Besides, the photocatalytic efficiency and structure of the MCN-60 composite basically show no change after three reuse cycles. Furthermore, trapping experiments and ESR analyses confirm that the O2– radical has a more dominant role than OH and holes (h+). The ofloxacin degradation mechanism and pathway are predicted by density functional theory (DFT) calculations and an intermediate analysis. Quantitative structure–activity relationship (QSAR) predictions reveal that the ofloxacin photocatalytic degradation process can reduce toxicity in a step-by-step manner. MOF-based materials have been confirmed to show high potential for practical application in removing emerging pollutants from wastewater.

Nanotechnology is an emerging technique drawing increasing attentions in biomedical, electronic, environmental, and industrial application. Nanoparticles (NPs) possess unique optical, electrical, catalytic, and thermal properties, among which magnetic NPs (MNPs) are one of the most important groups with excellent superparamagnetism property, large surface area, and biocompatibility. In this review, methods for synthesizing and functionalizing MNPs are summarized and linked to their applications in environmental science as either adsorbents or catalysts for removing contaminants from environmental matrices, illustrating stronger reactivity, higher removal capacity, and fast kinetics. Additionally, we also comprehensively discuss the application of MNPs as (bio)sensors to selectively and sensitively detect the presence of environmental contaminants or pathogenic bacteria. This work summarizes the recent progresses of using MNPs as powerful tools in environmental science and engineering, raising their state-of-art application from environmental perspectives and benefiting researchers interested in NPs and environmental studies.

Removal of n-butyl methacrylate from gas streams was studied in two parallel bio-trickling filters (BTFs), one packed with only ceramsite (BTFa) and the other with ceramsite coated with activated carbon fibre (BTFb). The performance of the two BTFs under various operational conditions was investigated to better understand the role of the activated carbon fibre. Results of the comparison experiments indicated that the use of activated carbon fibre could greatly shorten the start-up time of BTF. The removal efficiency of BTFb was 15.3% greater than that of BTFa under the empty bed residence time of 44s and the inlet concentration of 500 mg m−3, with the corresponding removal loading of 56.4 g m−3 h−1 and 46.5 g m−3 h−1, respectively. When the inlet loading of n-butyl methacrylate was lower than 34.0 g m−3 h−1, a complete removal of n-butyl methacrylate could be achieved in BTFb. The biomass of BTFb was 13.5 mg L−1 packing material greater than BTFa based on the dry weight, with the corresponding pressure drop 320 Pa m−1 higher than BTFa, meanwhile, the removal efficiency of BTFb remained higher all the time. The experiment showed that back washing proved a good way to reduce the pressure drop and biomass with no obvious changes in the removal efficiency.

Among the most efficient strategies to boost the electrochemical sensing and catalysis of Pt-based multimetallic nanomaterials is atomically manipulating the surface and near-surface nanostructures, which directly govern the adsorption behavior. Using one-dimensional PtCo urchin-like nanowires as the platform, we herein achieve the construction of high-index faceted Pt-skin configuration. Such unique structure shows excellent electrocatalytic performance toward the electrochemical detection of various molecules (H2O2, NH2NH2, dopamine, and acetaminophen), with the capability of real-time monitoring of H2O2 released from living cells and an impressive detection limit of 0.4 nM. Meanwhile, the combination of high-index facet and Pt-skin architecture also enables enhanced catalytic activity for the electro-reduction of oxygen in acid, realizing a very high mass activity of 2.2 A/mgPt. Our study demonstrates the great potential of surface and near-surface engineering at the atomic level in promoting the elect...

The flexible and stretchable electronics have been considered as next-generation electronics. Stretchable triboelectric nanogenerators (S-TENGs) with both multifunction and comfort have become a hot field of research for wearable electronic devices recently. Here, we designed an all-nanofiber-based, ultralight, S-TENG that could be softly attached on skins for motion energy harvesting and self-powered biomechanical monitoring. The S-TENG consisted of only two nanofiber membranes: a polyvinylidene fluoride nanofiber membrane (PVDFNM) supported by thermoplastic polyurethane nanofiber membrane (TPUNM) was used as the frictional layer, and a multiwalled carbon nanotube (MWCNT) conductive material screen-printed on the TPUNM was used as the electrode layer. Due to the excellent stretchability of TPUNM, the S-TENG could generate electricity under various types of deformation, and regains its original performance after intense mechanical extension, even if it is partially cut or damaged. Owing to the great elect...

Airborne ultrafine nanoparticle (UFNP) is a key factor causing heavy haze pollution in Beijing-Tianjin-Hebei, which is very harmful to human health and the environment. Removal of environmental UFNPs by porous material is an important method of air purification treatment. However, the specific mechanism by which porous material filters UFNPs is not clear. In this study, UFNPs with 2–10 nm diameter were removed by SBA-15 mesoporous silica molecular sieves with different pore sizes, and the filtration mechanism was analyzed using transmission electron microscopy (TEM), specific surface area tests (BET), and X-ray photoelectron spectroscopy (XPS). The analyses showed a distinctive filtration of UFNPs over the interior mesopore channels. The removal efficiencies of SBA-15 with different pore sizes were also compared, demonstrating the influence of the pore size and structure on most penetrating particle size (MPPS). The UFNP filtration efficiency of SBA-15 increased with the increase of pore size. Moreover, SBA-15-14.6 could effectively purify UFNPs, and it had the highest fractional diffusive filtration efficiency of 98.79% and a total efficiency of 92.58% for UFNPs. This study provides a technical basis for the filtration of UFNPs using mesoporous materials.

Dendritic growth of Li metal and its related safety issue in a liquid electrolyte greatly hinder the development of Li metal batteries. Herein, inspired by the Tai Chi philosophy of keeping rigid and flexible balance, we demonstrate a new rigid-flexible hybrid ionogel electrolyte composed of TiO2 rigid framework, PVDF-HFP flexible framework and LiTFSI-Py13TFSI ionic liquid for greatly boosting the performance of Li battery. The as-made hybrid ionogel electrolyte not only has excellent electrochemical properties, such as ionic conductivity up to 7.4 × 10−3 S/cm at 25 °C and anodic stability up to 5.5 V versus Li/Li+, but also has a high mechanical strength to withstand extrusion. These important features make it be able to realize the stable stripping/plating of Li anodes. The hybrid ionogel electrolyte enables the assembled LiFePO4/Li batteries to be successfully cycled at wide C rate (0.1–2.0 C) and exhibit no significant capacity degradation for up to 500 days (about 600 cycles) at a 0.1 C rate. The design from Tai Chi philosophy to protect Li metal opens new opportunities to realize high energy-density Li metal batteries.

Air–water mixing flows are commonly formed in pressurized water supply pipes due to dissolved air from the water under low pressure conditions, and air injected through system controls and associated valves and pumps. This paper investigates transient behaviours of air–water mixing flows in viscoelastic pipes through laboratory experimental tests, numerical modelling and theoretical analysis. Two numerical schemes – the discrete vaporous cavity model (DVCM) and the discrete gas cavity model (DGCM), which are firstly calibrated and validated by the experimental data gained in this study, are adopted for comparative study for their validity and accuracy for modelling transient air–water mixing flows in viscoelastic pipes. With the validated model, the results of systematic analysis show that the effect of pipe-wall viscoelasticity on transient amplitude damping decreases with the increase of air content, and the frequency shifting rate of viscoelastic effect is negligible in comparison with that of ...

The combustion behaviors of sewage sludge (SS), pulverized coal (PC), and their blends were studied using a thermogravimetric analyzer. The effect of the mass ratio of SS to PC on the co-combustion characteristics was analyzed. The experiments showed that the ignition performance of the blends improved significantly as the mass percentage of SS increased, but its combustion intensity decreased. The burnout temperature (Tb) and comprehensive combustibility index (S) of the blends were almost unchanged when the mass percentage of SS was less than 10%. However, a high mass percentage of SS (>10%) resulted in a great increase in Tb and a notable decrease in S. Subsequently, the effects of different catalysts (CaO, CeO2, MnO2, and Fe2O3) on the combustion characteristics and activation energy of the SS/PC blend were investigated. The four catalysts promoted the release and combustion of volatile matters in the blended fuels and shifted their combustion profiles to a low temperature. In addition, their peak separating tendencies were obvious at 350–550 C, resulting in high peak widths. All the catalysts improved combustion activity of the blended fuel and accelerated fixed carbon combustion, which decreased the ignition temperature and burnout temperature of the fuels. CeO2 had the best catalytic effects in terms of the comprehensive combustion performance and activation energy, followed closely by Fe2O3. However, the rare-earth compounds are expensive to be applied in the catalytic combustion process of SS/PC blend at present. Based on both catalytic effects and economy, Fe2O3 was potentially an optimal option for catalytic combustion among the tested catalysts.

Energy efficient buildings require materials with a low thermal conductivity and a high fire resistance. Traditional organic insulation materials are limited by their poor fire resistance and inorganic insulation materials are either brittle or display a high thermal conductivity. Herein we report a mechanically resilient organic/inorganic composite aerogel with a thermal conductivity significantly lower than expanded polystyrene and excellent fire resistance. Co-polymerization and nanoscale phase separation of the phenol-formaldehyde-resin (PFR) and silica generate a binary network with domain sizes below 20 nm. The PFR/SiO2 aerogel can resist a high-temperature flame without disintegration and prevents the temperature on the non-exposed side from increasing above the temperature critical for the collapse of reinforced concrete structures.

Simultaneous oxidation of Hg0 and NH3-SCR of NO by catalyst is one of the key methods for co-purification of coal-fired flue gas. Till now, the interaction between the oxidation of Hg0 and NH3-SCR of NO and its mechanism have not clarified. In this study, a series of nanophase Ce x Zr y Mn z O2 was prepared for the simultaneous oxidation of Hg0 and NH3-SCR of NO at low temperature. The catalysts were characterized using surface area analysis, X-ray diffraction, temperature-programmed techniques, and several types of microscopy and spectroscopy. The experimental results indicated that the Ce0.47Zr0.22Mn0.31O2 exhibited superior Hg0 removal efficiency (> 99%) and NO conversion efficiency (> 90%) even at 150 °C, and it also exhibited a good durability in the presence of SO2 and H2O. The excellent performance of Ce0.47Zr0.22Mn0.31O2 on co-purifying Hg0 and NO was due to the stronger synergistic effects of Ce-Zr-Mn in Ce0.47Zr0.22Mn0.31O2 than that of the others, which was illustrated by the characterization results of XPS, XRD, and FT-IR. Moreover, it was found that the NO conversion of Ce0.47Zr0.22Mn0.31O2 could be slightly influenced by Hg0 and was decreased about 4% to the max, while that of Hg0 could rarely be affected by the selected catalytic reduction process of NO. It might be due to the co-purification mechanism of NO and Hg0. The mechanism of the simultaneous oxidation of Hg0 and NH3-SCR of NO was mainly due to the synergetic effect on the mobility of surface oxygen and the activation of lattice oxygen of Ce0.47Zr0.22Mn0.31O2. The effect of the oxidation of Hg0 on the NH3-SCR of NO was mainly due to the absorbed Hg0/Hg2+ on the surface of Ce0.47Zr0.22Mn0.31O2, which attenuated the formation of NH3(ad), −NH2(ad), and NH4+ on its acid sites. Similarly, the NH3-SCR of NO process could hardly influence the oxidation of Hg0 when NO and Hg0 were co-purified.