Investigation of Molybdenum based Nanomaterials as High Performance Anodes for Advanced Lithium Ion Battery

Electrodes adopting multi-electron reactions provide significant opportunities for the development of high-energy lithium ion batteries. Most conversion reaction based transition metal compounds exhibit much higher theoretical capacities than graphite. Among the transition metal compounds, molybdenum compounds have proved to be very interesting, since they often exhibit various stoichiometry, tuned band gaps, and rich chemical valences. These features provide an extraordinary basis for the full utilization of molybdenum compounds in advanced energy storage systems

The Evolution Response of Ecosystem Cultural Services under Different Scenarios Based on System Dynamics

Cultural ecosystem services (CES) are a significant part of the ecosystem and are considered to be a core component of human welfare and ecosystem protection. CES have been historically difficult to quantitatively evaluate because of their subjectivity and intangibility. Additionally, their evolution over time has rarely been explored. Here, we quantitatively evaluated various CES and generated corresponding value index (VI) maps. We then further explored the evolution of CES characteristics over space and time. We selected Xi'an as the study area and applied the Social Values of Ecosystem Services (SolVES) model to evaluate CES and generate three specific VI maps. A system dynamics model based on socioeconomic and survey data of CES for each administrative division was established. Finally, we simulated four developmental scenarios in order to predict potential developmental changes of CES in 2030 under these different scenarios. This study provides a method for evaluating CES and explores the application of system dynamics to different fields. Additionally, our findings may provide guidance for the formulation of regional policies and support missions to improve civilizations within ecological systems, coordinate future economic growth with ecosystem services, and achieve sustainable development

A lanthanide functionalized MOF hybrid for ratiometric luminescence detection of an anthrax biomarker

Dipicolinic acid (DPA) can serve as a convenient biomarker for Bacillus anthracis, which is an extremely hazardous pathogen and can be used as a biological weapon. Herein, we demonstrate a ratiometric luminescent sensor of DPA based on a dual-emissive MOF hybrid, which is developed by encapsulation of Tb 3+ cations into an anionic MOF through a cation exchange process. The Tb 3+ @MOF hybrid well inherits the intrinsic ligand emission of the host framework and the Tb 3+ emission. The parent framework can function as a host matrix to sensitize and protect the emission of incorporated Tb 3+ . The Tb 3+ emission within the MOF hybrid is significantly enhanced in the presence of DPA molecules owing to the occurrence of antenna sensitization upon the formation of the Tb-DPA complex, while the ligand emission is insensitive to DPA. This unique ratiometric luminescence response of the Tb 3+ @MOF hybrid towards DPA can be exploited for sensitive self-calibrated detection of DPA. The Tb 3+ @MOF sensor shows a fast response rate, high sensitivity and selectivity with a limit of detection of 3.6 nM. Besides, the feasibility of this sensor operating in real samples is demonstrated by the good recovery of DPA in human serum. The present study provides a promising luminescent platform for routine analysis of an anthrax biomarker

A luminescent Lanthanide-free MOF nanohybrid for highly sensitive ratiometric temperature sensing in physiological range

Luminescent MOF materials with tunable emissions and energy/charge transfer processes have been extensively explored as ratiometric temperature sensors. However, most of the ratiometric MOF thermometers reported thus far are based on the MOFs containing photoactive lanthanides, which are potentially facing cost issue and serious supply shortage. Here, we present a ratiometric luminescent thermometer based on a dual-emitting lanthanide-free MOF hybrid, which is developed by encapsulation of a fluorescent dye into a robust nanocrystalline zirconium-based MOF through a one-pot synthesis approach. The structure and morphology of the hybrid product was characterized by Powder X-ray diffraction (PXRD), N 2 adsorption-desorption measurement and Scanning electron microscopy (SEM). The pore confinement effect well isolates the guest dye molecules and therefore suppresses the nonradiative energy transfer process between dye molecules. The incorporated dye emission is mainly sensitized by the organic linkers within MOF through fluorescence resonance energy transfer. The ratiometric luminescence of the MOF hybrid shows a significant response to temperature due to the thermal-related back energy transfer process from dye molecules and organic linkers, thus can be exploited for self-calibrated temperature sensing. The maximum thermometric sensitivity is 1.19% °C −1 in the physiological temperature range, which is among the highest for the ratiomtric MOF thermometers that operating in 25-45 °C. The temp erature resolution is better than 0.1 °C over the entire operative range (20-60 °C). By integrating the advantages of excellent stability, nanoscale nature, and high sensitivity and precision in the physiological temperature range, this dye@MOF hybrid might have potential application in biomedical diagnosis. What\u27 more, this work has expanded the possibility of non-lanthanide luminescent MOF materials for the development of ratiometric temperature sensors

Electrospun core-shell Mn3O4/carbon fibers as high-performance cathode materials for aqueous zinc-ion batteries

© 2020 Elsevier Ltd Core-shell Mn3O4/carbon (Mn3O4@C) hybrid fiber are synthesized by encapsulating Mn3O4 nanoparticles (NPs) in the hollow carbon fibers (Mn3O4@HCFs) according to the coaxial electrospinning technique. As the aqueous Zinc ion battery (ZIBs) cathode, the well-defined Mn3O4@HCFs with 12.7 wt % carbon exhibits superior rate capability (215.8 and 115.7 mAh g−1 at 0.3 and 2.0 A g−1, respectively) and excellent cycling stability (225 mAh g−1 remaining at the current density of 400 mA g−1 after 1300 cycles). The outstanding electrochemical performances are attributed to the core-shell structure of the Mn3O4@HCFs with much void spaces. The carbon framework on the surface of the Mn3O4 NPs can not only relieve the volume expansion of Mn3O4 during the discharging, but also optimize the electron transportation inside these fibers for the electrode. Furthermore, the amorphous carbon shell could also reduce the dissolution of the Mn3O4 NPs during cycling. This work will provide a new pathway of a technique for enhancing the manganese-based cathode materials for the high-powered rechargeable aqueous ZIBs

Detection and removal of antibiotic tetracycline in water with a highly stable luminescent MOF

Antibiotic tetracycline (TC) is a sort of main contaminates in water, and of adverse effect on ecosystems and human health. The development of simple and efficient methods for both detection and removal of TC in water is highly desirable but remains challenging. Herein, a dual-functional platform for detection and removal of antibiotic tetracycline (TC) is developed by a highly stable luminescent zirconium-based MOF (PCN-128Y). The detection is based on the efficient luminescence quenching of the PCN-128Y toward TC. Theoretical/experimental studies reveal that the luminescence quenching can be attributed to a combined effect of the strong absorption of TC at the excitation wavelength and the photo-induced electron transfer process from the ligand of PCN-128Y to TC. The strong cheating metal-ligand bonding between Zr 6 nodes and TC through solvent-assisted ligand incorporation is suggested to mainly account for the high adsorption capability of PCN-128Y toward TC in water. The preconcentration of TC within the pores of PCN-128Y induced by the adsorption process makes TC contact with the framework more sufficient, thus significantly enhances the efficiency of TC sensing. This work is the first example demonstrating that MOF materials can integrate the functions of detection and removal of antibiotic TC in water, which highlights the opportunity of luminescent MOFs in the application of wastewater treatment

A pyrene-involved luminescent MOF for monitoring 1-hydroxypyrene, a biomarker for human intoxication of PAH carcinogens

1-Hydroxypyrene (1-HP) is a urinary metabolite of polycyclic aromatic hydrocarbons (PAHs), and can function as a convenient biomarker for human intoxication of PAH carcinogens. The development of simple 1-HP sensors with high sensitivity and fast response is highly desirable. Herein, we demonstrate that a robust microcrystalline MOF with fluorescent pyrene cores, NU-1000, exhibits sensitive luminescence detection of urinary 1-HP. The pyrene core within NU-1000 behaves as the signal converter, whose luminescence is significantly quenched upon coming into contact with 1-HP owing to the efficient π-π charge transfer interactions between highly conjugated 1-HP and pyrene cores in NU-1000. The pore confinement effect of the molecular-sized channel of NU-1000 facilitates the preconcentration of 1-HP within NU-1000, which makes 1-HP contact with NU-1000 more sufficient therefore enhancing the detection efficiency. The charge transfer-related quenching mechanism is elucidated by diffuse-reflectance UV-vis and electron paramagnetic resonance (EPR) measurements, and a radical pair state is observed in NU-1000 upon accommodation of 1-HP. This work provides important insights into the development of MOF-based luminescent sensors for 1-HP, and should stimulate further studies toward designing more efficient MOFs with highly conjugated luminescent cores for 1-HP sensing

Ratiometric and Turn-On Luminescence Detection of Water in Organic Solvents Using a Responsive Europium-Organic Framework

The development of simple, rapid-response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual-emitting europium-organic framework (Eu-MOF), which is assembled from a purposely selected 2-aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched-on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu 3+ emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn-on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu-MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05-10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l\u27Eclairage (CIE) chromaticity coordinate. The present Eu-MOF sensor featuring high sensitivity and reusability, self-calibration, simple fabrication and operation, and capability for real-time and in situ detection is expected to have practical applications in water analysis for industrial processes

Borohydride-Scaffolded Li/Na/Mg Fast Ionic Conductors for Promising Solid-State Electrolytes

Borohydride solid-state electrolytes with room-temperature ionic conductivity up to ≈70 mS cm−1 have achieved impressive progress and quickly taken their place among the superionic conductive solid-state electrolytes. Here, the focus is on state-of-the-art developments in borohydride solid-state electrolytes, including their competitive ionic-conductive performance, current limitations for practical applications in solid-state batteries, and the strategies to address their problems. To open, fast Li/Na/Mg ionic conductivity in electrolytes with BH4− groups, approaches to engineering borohydrides with enhanced ionic conductivity, and later on the superionic conductivity of polyhedral borohydrides, their correlated conductive kinetics/thermodynamics, and the theoretically predicted high conductive derivatives are discussed. Furthermore, the validity of borohydride pairing with coated oxides, sulfur, organic electrodes, MgH2, TiS2, Li4Ti5O12, electrode materials, etc., is surveyed in solid-state batteries. From the viewpoint of compatible cathodes, the stable electrochemical windows of borohydride solid-state electrolytes, the electrode/electrolyte interface behavior and battery device design, and the performance optimization of borohydride-based solid-state batteries are also discussed in detail. A comprehensive coverage of emerging trends in borohydride solid-state electrolytes is provided and future maps to promote better performance of borohydride SSEs are sketched out, which will pave the way for their further development in the field of energy storage