Nitrogen-Anchored Boridene Enables Mg-CO2 Batteries with High Reversibility.

Nanoscale defect engineering plays a crucial role in incorporating extraordinary catalytic properties in two-dimensional materials by varying the surface groups or site interactions. Herein, we synthesized high-loaded nitrogen-doped Boridene (N-Boridene (Mo4/3(BnN1-n)2-mTz), N-doped concentration up to 26.78 at %) nanosheets by chemical exfoliation followed by cyanamide intercalation. Three different nitrogen sites are observed in N-Boridene, wherein the site of boron vacancy substitution mainly accounts for its high chemical activity. Attractively, as a cathode for Mg-CO2 batteries, it delivers a long-term lifetime (305 cycles), high-energy efficiency (93.6%), and ultralow overpotential (∼0.09 V) at a high current of 200 mA g-1, which overwhelms all Mg-CO2 batteries reported so far. Experimental and computational studies suggest that N-Boridene can remarkably change the adsorption energy of the reaction products and lower the energy barrier of the rate-determining step (*MgCO2 → *MgCO3·xH2O), resulting in the rapid reversible formation/decomposition of new MgCO3·5H2O products. The surging Boridene materials with defects provide substantial opportunities to develop other heterogeneous catalysts for efficient capture and converting of CO2.

N-Decorated Main-Group MgAl2O4 Spinel: Unlocking Exceptional Oxygen Reduction Activity for Zn-Air Batteries.

The development of economical and efficient oxygen reduction reaction (ORR) catalysts is crucial to accelerate the widespread application rhythm of aqueous rechargeable zinc-air batteries (ZABs). Here, a strategy is reported that the modification of the binding energy for reaction intermediates by the axial N-group converts the inactive spinel MgAl2O4 into the active motif of MgAl2O4-N. It is found that the introduction of N species can effectively optimize the electronic configuration of MgAl2O4, thereby significantly reducing the adsorption strength of *OH and boosting the reaction process. This main-group MgAl2O4-N catalyst exhibits a high ORR activity in a broad pH range from acidic and alkaline environments. The aqueous ZABs assembled with MgAl2O4-N shows a peak power density of 158.5 mW cm-2, the long-term cyclability over 2000 h and the high stability in the temperature range from -10 to 50 °C, outperforming the commercial Pt/C in terms of activity and stability. This work not only serves as a significant candidate for the robust ORR electrocatalysts of aqueous ZABs, but also paves a new route for the effective reutilization of waste Mg alloys.

Natural Mediterranean Spotted Fever Foci, Qingdao, China.

We sequenced DNA from spleens of rodents captured in rural areas of Qingdao, East China, during 2013-2015. We found 1 Apodemus agrarius mouse infected with Rickettsia conorii, indicating a natural Mediterranean spotted fever foci exists in East China and that the range of R. conorii could be expanding.

Self-Assembled Sandwich-like MXene-Derived Composites as Highly Efficient and Sustainable Catalysts for Wastewater Treatment.

Photocatalysts play an increasingly important role in environmental remediation polluted by industrial wastewater. However, the preparation of adsorbents and catalysts with high activity by simple and easy methods is still a great challenge. Here, sandwich-like composite catalyst Cu2O/TiO2/Ti3C2 was prepared by an easily available solvent reduction measure for the highly efficient catalytic nitro compounds. In particular, sandwich-like composite catalyst Cu2O/TiO2/Ti3C2 exhibits excellent catalysis for 2-nitroaniline (2-NA) and 4-nitrophenol (4-NP), and its pseudo-first-order reaction rate constants (k) are 0.163 and 0.114 min-1, respectively. Interestingly, even after eight consecutive cycles of catalytic experiments, the conversion rates of catalytic 2-NA and 4-NP are still greater than 95 and 92%, respectively, demonstrating that the obtained catalyst has excellent catalytic capability and a high reutilization rate. The excellent catalytic performances of Cu2O/TiO2/Ti3C2 can be attributed to the fact that Ti3C2 provides a greater reaction site for the formation of Cu2O and reduces the aggregation during the formation of Cu2O by in situ synthesis. Therefore, ternary composite catalyst Cu2O/TiO2/Ti3C2 prepared by solvent reduction not only supplies a technical method for the catalytic reaction of MXene-based material but also lays the foundation for the development of new photocatalysts.

Fabrication of hierarchical SrTiO3@MoS2 heterostructure nanofibers as efficient and low-cost electrocatalysts for hydrogen-evolution reactions.

The construction of low-cost, high-performance electrocatalysts instead of platinum catalysts is critical to solving the energy crisis. Here, using simple electrospinning and hydrothermal methods, new MoS2 nanosheets on SrTiO3 nanofibers (NFs) and 2D SrTiO3@MoS2 heterostructure NFs are synthesized. In addition, SrTiO3@MoS2 heterostructure NFs are compared with bare SrTiO3 NFs and MoS2 nanosheets. Importantly, the prepared SrTiO3@MoS2 heterostructure shows better hydrogen-evolution reaction performance than other MoS2-based electrocatalysts with an overpotential of 165 mV at 10 mA cm-2, a Tafel slope of 81.41 mV dec-1, and long-term electrochemical durability of 3000 cycles. Therefore, the present work strongly demonstrates the positive synergy between SrTiO3 NFs and layered MoS2, and also provides a strategy for preparing low-cost and high-activity water-decomposition electrocatalysts.

A Co-Doped MnO2 Catalyst for Li-CO2 Batteries with Low Overpotential and Ultrahigh Cyclability.

Li-CO2 batteries can not only capture CO2 to solve the greenhouse effect but also serve as next-generation energy storage devices on the merits of economical, environmentally-friendly, and sustainable aspects. However, these batteries are suffering from two main drawbacks: high overpotential and poor cyclability, severely postponing the acceleration of their applications. Herein, a new Co-doped alpha-MnO2 nanowire catalyst is prepared for rechargeable Li-CO2 batteries, which exhibits a high capacity (8160 mA h g-1 at a current density of 100 mA g-1 ), a low overpotential (≈0.73 V), and an ultrahigh cyclability (over 500 cycles at a current density of 100 mA g-1 ), exceeding those of Li-CO2 batteries reported so far. The reaction mechanisms are interpreted depending on in situ experimental observations in combination with density functional theory calculations. The outstanding electrochemical properties are mostly associated with a high conductivity, a large fraction of hierarchical channels, and a unique Co interstitial doping, which might be of benefit for the diffusion of CO2 , the reversibility of Li2 CO3 products, and the prohibition of side reactions between electrolyte and electrode. These results shed light on both CO2 fixation and new Li-CO2 batteries for energy storage.

In Situ Atomic-Scale Oscillation Sublimation of Magnesium under CO2 Conditions.

Understanding the interactive role between Mg and CO2 is crucial for many technological applications, including CO2 storage, melting protection, corrosion resistance, and ceramic welding. Here we report observations of rapid oscillation sublimation of Mg at room temperature in the presence of both CO2 gas and electron irradiation using environmental transmission electron microscopy. The sublimation is mainly related to phase transformation of amorphous MgCO3. Differing from the direct formation of gas-state MgCO3, which attributes to the sublimation of pure Mg under a mild electron beam dose, a unique oscillation process is detected during the process of Mg sublimation under a harsh electron beam dose. The main reason stems from the first-order reaction of a reversible decomposition-formation of amorphous MgCO3. These atomic-level results provide some interesting insights into the interactive role between Mg and CO2 under electron beam irradiation.

Chiral Nanostructured Composite Films via Solvent-Tuned Self-Assembly and Their Enantioselective Performances.

Chiral nanostructures exhibited distinctive functions and attractive applications in complex biological systems, which demonstrated the subject of many outstanding research studies. In this work, various hierarchical composite film nanostructures were designed via supramolecular self-assembly using chiral amphiphilic glutamate derivatives and achiral porphyrin derivatives and their macroscopic enantioselective recognition properties were investigated. We have found that intermolecular hydrogen-bonding interactions between water (donor and acceptor) and N, N-dimethylformamide (DMF) as well as chloroform (CHCl3) (acceptor only) and DMF could subtly alter the molecular packing and significantly affected the supramolecular self-assembled nanostructures and triggered circular dichroism (CD) signal reversal. Present research work exemplified a feasible method to fabricate chiral flower-like and brick-like nanostructure films in different mixed solvents and large-scale chiral transfer from the molecular level to complex structures, which also provided a facile approach to identify certain l-/d-amino acids by means of contact angle detection using present obtained self-assembled composted films.

Carbon Nanomaterials for Targeted Cancer Therapy Drugs: A Critical Review.

Cancer represents one of the main causes of human death in developed countries. Most current therapies, unfortunately, carry a number of side effects, such as toxicity and damage to healthy cells, as well as the risk of resistance and recurrence. Therefore, cancer research is trying to develop therapeutic procedures with minimal negative consequences. The use of nanomaterial-based systems appears to be one of them. In recent years, great progress has been made in the field using nanomaterials with high potential in biomedical applications. Carbon nanomaterials, thanks to their unique physicochemical properties, are gaining more and more popularity in cancer therapy. They are valued especially for their ability to deliver drugs or small therapeutic molecules to these cells. Through surface functionalization, they can specifically target tumor tissues, increasing the therapeutic potential and significantly reducing the adverse effects of therapy. Their potential future use could, therefore, be as vehicles for drug delivery. This review presents the latest findings of research studies using carbon nanomaterials in the treatment of various types of cancer. To carry out this study, different databases such as Web of Science, PubMed, MEDLINE and Google Scholar were employed. The findings of research studies chosen from more than 2000 viewed scientific publications from the last 15 years were compared.

Facile preparation of self-assembled hydrogels constructed from poly-cyclodextrin and poly-adamantane as highly selective adsorbents for wastewater treatment.

Self-assembled hydrogel materials constructed from cyclodextrin polymer (P-CD)/adamantane-modified poly acrylic acid (PAA-Ad) were designed and prepared via host-guest interactions. It was observed that the prepared supramolecular hydrogels had an interconnected three-dimensional porous network. In addition, the obtained hydrogels showed a recovery performance and it was confirmed that the host-guest interactions between ß-cyclodextrin and adamantane were the main driving force for the formation of the hydrogels. The mechanical properties of the hydrogels could be adjusted by varying the concentrations of PAA-Ad. In particular, the prepared supramolecular hydrogels exhibited superior performances in water purification. The results demonstrated that the hydrogels possessed different mechanisms in the adsorption of the four typical poisonous organic dye molecules used, including bisphenol A (BPA), 4-aminoazobenzene (N-Azo), methylene blue (MB), and rhodamine B (RhB). The hydrogels mainly adsorbed N-Azo by host-guest interaction and adsorbed BPA by host-guest interaction and hydrogen bond synergy. They also adsorbed MB and RhB by hydrogen bonding and electrostatic interaction.

Facile preparation of a self-assembled Artemia cyst shell-TiO2-MoS2 porous composite structure with highly efficient catalytic reduction of nitro compounds for wastewater treatment.

The catalytic reduction of nitro compounds is currently a hot research area, how to efficiently and stably degrade such toxic and harmful substances has become the research goal of many researchers. In this work, an Artemia cyst shell (ACS)-TiO2-MoS2 ternary porous structure was proposed and prepared as a catalyst for the reduction of 2-nitroaniline (2-NA) and 4-nitrophenol (4-NP). The ACS has a large number of porous structures, exhibits a good binding ability with TiO2 and MoS2, and provides a large number of active sites for the catalytic reduction process. The obtained composite material has a good reduction effect on 4-NP and 2-NA, with a good stability and recyclability, which is obviously higher than the reduction effect of ACS-TiO2 and MoS2 under the same conditions. This work provides ideas for the design of porous catalytic materials.

In Situ Imaging the Oxygen Reduction Reactions of Solid State Na-O2 Batteries with CuO Nanowires as the Air Cathode.

We report real time imaging of the oxygen reduction reactions (ORRs) in all solid state sodium oxygen batteries (SOBs) with CuO nanowires (NWs) as the air cathode in an aberration-corrected environmental transmission electron microscope under an oxygen environment. The ORR occurred in a distinct two-step reaction, namely, a first conversion reaction followed by a second multiple ORR. In the former, CuO was first converted to Cu2O and then to Cu; in the latter, NaO2 formed first, followed by its disproportionation to Na2O2 and O2. Concurrent with the two distinct electrochemical reactions, the CuO NWs experienced multiple consecutive large volume expansions. It is evident that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter one-electron-transfer ORR, leading to the formation of NaO2. Remarkably, no carbonate formation was detected in the oxygen cathode after cycling due to the absence of carbon source in the whole battery setup. These results provide fundamental understanding into the oxygen chemistry in the carbonless air cathode in all solid state Na-O2 batteries.

Selective and Efficient Removal of Fluoride from Water: In Situ Engineered Amyloid Fibril/ZrO2 Hybrid Membranes.

We report a new strategy for efficient removal of F- from contaminated water streams, and it relies on carbon hybrid membranes made of amyloid fibril/ZrO2 nanoparticles (<10 nm). These membranes exhibit superior selectivity for F- against various competitive ions, with a distribution coefficient (Kd ) as high as 6820 mL g-1 , exceeding commercial ion-exchange resins (IRA-900) by 180 times and outdoing the performance of most commercial carbon-activated aluminum membranes. At both low and high (ca. 200 mg L-1 ) F- concentrations, the membrane efficiency exceeds 99.5 % removal. For real untreated municipal tap water (ca. 2.8 mg L-1 ) under continuous operating mode, data indicates that about 1750 kg water m-2 membrane can be treated while maintaining drinking water quality, and the saturated membranes can be regenerated and reused several times without decrease in performance. This technology is promising for mitigating the problem of fluoride water contamination worldwide.

Facile synthesis of self-assembled carbon nanotubes/dye composite films for sensitive electrochemical determination of Cd(II) ions.

A new type of voltammetric sensor material has been fabricated via a facile self-assembled method. A modified glassy carbon electrode (GCE) by phenylsulfonic groups grafted multi-walled carbon nanotubes (CNT-SO3H) with dye molecules via Langmuir-Blodgett (LB) assembling (CNT-SO3H/dye-LB/GCE) were prepared for detecting trace levels of cadmium (Cd2+) ions by square wave anodic stripping voltammetry. The synergy effect between CNT-SO3H and dye as well as orderly aggregates in composite LB films contributed to greatly enhancing the determination performance. Under selected conditions, voltammetric response of the fabricated electrochemical sensor in 0.1 M acetate buffer solution containing Bi3+ ions for Cd2+ ions was linear with its concentration in the range 0.1 to 1.2 µM, with a detection limit of 0.08 µM. In addition, the preparation process of self-assembled composite film modified electrodes was simple, non-toxic, exhibiting higher sensitivity and potential application prospects in aspects of heavy metal ions detection and environmental analysis.

Achieving High Strength and Ductility in Magnesium Alloys via Densely Hierarchical Double Contraction Nanotwins.

Light-weight magnesium alloys with high strength are especially desirable for the applications in transportation, aerospace, electronic components, and implants owing to their high stiffness, abundant raw materials, and environmental friendliness. Unfortunately, conventional strengthening methods mainly involve the formation of internal defects, in which particles and grain boundaries prohibit dislocation motion as well as compromise ductility invariably. Herein, we report a novel strategy for simultaneously achieving high specific yield strength (∼160 kN m kg-1) and good elongation (∼23.6%) in a duplex magnesium alloy containing 8 wt % lithium at room temperature, based on the introduction of densely hierarchical {101̅1}-{101̅1} double contraction nanotwins (DCTWs) and full-coherent hexagonal close-packed (hcp) particles in twin boundaries by ultrahigh pressure technique. These hierarchical nanoscaled DCTWs with stable interface characteristics not only bestow a large fraction of twin interface but also form interlaced continuous grids, hindering possible dislocation motions. Meanwhile, orderly aggregated particles offer supplemental pinning effect for overcoming latent softening roles of twin interface movement and detwinning process. The processes lead to a concomitant but unusual situation where double contraction twinning strengthens rather than weakens magnesium alloys. Those cutting-edge results provide underlying insights toward designing alternative and more innovative hcp-type structural materials with superior mechanical properties.

Self-Assembled Luminescent Quantum Dots To Generate Full-Color and White Circularly Polarized Light.

The design and fabrication of quantum dots (QDs) with circularly polarized luminescence (CPL) has been a great challenge in developing chiroptical materials. We herein propose an alternative to the use of chiral capping reagents on QDs for the fabrication of CPL-active QDs that is based on the supramolecular self-assembly of achiral QDs with chiral gelators. Full-color-tunable CPL-active QDs were obtained by simple mixing or gelation of a chiral gelator and achiral 3-mercaptopropionic acid capped QDs. In addition, the handedness of the CPL can be controlled by the supramolecular chirality of the gels. Moreover, QDs with circularly polarized white light emission were fabricated for the first time by tuning the blending ratio of colorful QDs in the gel. The chirality transfer in the co-assembly of the achiral QDs with the gelator and the spacer effect of the capping reagents on the QD surface are also discussed. This work provides new insight into the design of functional chiroptical materials.

Unique lead adsorption behavior of activated hydroxyl group in two-dimensional titanium carbide.

The functional groups and site interactions on the surfaces of two-dimensional (2D) layered titanium carbide can be tailored to attain some extraordinary physical properties. Herein a 2D alk-MXene (Ti3C2(OH/ONa)(x)F(2-x)) material, prepared by chemical exfoliation followed by alkalization intercalation, exhibits preferential Pb(II) sorption behavior when competing cations (Ca(II)/Mg(II)) coexisted at high levels. Kinetic tests show that the sorption equilibrium is achieved in as short a time as 120 s. Attractively, the alk-MXene presents efficient Pb(II) uptake performance with the applied sorption capacities of 4500 kg water per alk-MXene, and the effluent Pb(II) contents are below the drinking water standard recommended by the World Health Organization (10 µg/L). Experimental and computational studies suggest that the sorption behavior is related to the hydroxyl groups in activated Ti sites, where Pb(II) ion exchange is facilitated by the formation of a hexagonal potential trap.

A Sodiophilic Amyloid Fibril Modified Separator for Dendrite-Free Sodium-Metal Batteries.

Sodium (Na) batteries are being considered as prospective candidates for the next generation of secondary batteries in contrast to lithium-based batteries, due to their high raw-material abundance, low cost, and sustainability. However, the unfavorable growth of Na-metal deposition and severe interfacial reactions have prevented their large-scale applications. Here, a vacuum filtration strategy, through amyloid-fibril-modified glass-fiber separators, is proposed to address these issues. The modified symmetric cell can be cycled for 1800 h, surpassing the performance of previously reported Na-based electrodes under an ester-based electrolyte. Moreover, the Na/Na3 V2 (PO4 )3 full cell with a sodiophilic amyloid-fibril-modified separator exhibits a capacity retention of 87.13% even after 1000 cycles. Both the experimental and the theoretical results show that the sodiophilic amyloid fibril homogenizes the electric field and Na-ion concentration, fundamentally inhibiting dendrite formation. Simultaneously, the glutamine amino acids in the amyloid fibril have the highest adsorption energy for Na, resulting in the formation of a stable Na3 N- and NaNx Oy -rich solid-electrolyte-interface film on the anode during cycling. This work provides not only a possible pathway to solve the dendrite problem in metal batteries using environmentally friendly biomacromolecular materials, but also a new direction for expanding biomaterial applications.

Construction of cellulose acetate-based composite nanofiber films with effective antibacterial and filtration properties.

In recent years, the safety of public health has attracted more and more attention. In order to avoid the spread of bacteria and reduce the diseases caused by their invasion of the human body, novel filtration and antibacterial materials have attracted more and more attention. In this work, the antibacterial agents silver nanoparticles (AgNPs) and cetylpyridine bromide (CPB) were introduced into a cellulose acetate (CA) nanofiber film by electrospinning technology to prepare CA-based composite films with good antibacterial and filtration properties. The results of the antibacterial test of the composite nanofiber films showed that AgNPs and CPB had synergistic antibacterial effects and exhibited good antibacterial properties against a variety of bacteria. In addition, in vitro cytotoxicity, skin irritation and skin sensitization experiments proved that the CA/AgNPs, CA/CPB and CA/CPB/AgNPs films produced no skin irritation or sensitization in the short term. These are expected to become potential materials for the preparation of new antibacterial masks. This work provides a new idea for developing materials with good antibacterial properties for enhancing protection via filtration masks.

Reversible Insertion of [AlCl4 ]- Superhalides in Graphite.

Graphite-based dual-ion batteries are with potential higher energy density, making them a unique candidate in energy storage systems. However, anion insertion into graphite in aqueous environment remains a significant challenge. Herein, we report that the reversible insertion of Al-Cl superhalide into expanded graphite (EG) delivers an ultrahigh specific capacity of ~171 mAh g-1 from an aqueous deep eutectic solvent (DES) gel electrolyte of 50 m ChCl+5 m AlCl3 . High-resolution transmission electron microscopy (HRTEM), Raman spectra and X-ray diffraction (XRD) show that the EG generates turbostratic structure during Al-Cl superhalide (de)insertion instead of presenting typical graphite intercalation compounds (GIC), thus attributing to the high capacity during Al-Cl superhalide insertion.