Fifteen polycyclic aromatic hydrocarbons (PAHs) were detected in seawater and atmosphere of Bransfield Strait. The concentration of ∑15PAH in the atmosphere ranged from 3.75 to 8.53 ng m−3, and ...three-ring PAHs were the most abundant compounds. Dissolved ∑15PAH in seawater ranged from 5.42 to 34.37 ng L−1, and the level of PAHs was markedly different on each side of the strait. The air–sea gas exchange process and molecular diagnostic ratios were calculated, results showed that the environmental behavior of PAHs was net deposition along this cruise. Given the changes in global transport routes of pollutants under global warming, the role of long-range transport (LRT) may be enhanced. Taking the Antarctic as a sink of PAHs due to the LRT and net deposition, PAHs will continue to load into the seawater of this area via atmospheric deposition, which contributes to improving our understanding of the environmental behavior of PAHs.
•Polycyclic aromatic hydrocarbons (PAHs) were investigated in the seawater and atmosphere at Bransfield Strait, Antarctica.•Air-water gas exchange exhibited a net deposition trend from atmosphere to Deep Ocean.•Antarctic environments still played a sink role of global contaminants.•Distribution characteristics of Antarctic contaminants are influenced by both local sources and long-range transport.
Molybdenum disulfide (MoS2) is a promising high‐capacity anode for lithium‐ion batteries. However, the conversion reaction mechanism of MoS2 (the delithiation pathway in particular) has been ...controversial, which limits the rational optimization of its electrochemical performance. The main challenge is how to precisely identify the amorphous nanomaterials generated during lithiation/delithiation. Here, the structural evolutions of MoS2 during lithiation/delithiation are systematically investigated using synchrotron X‐ray absorption spectroscopy at Mo K‐edge and S K‐edge and Raman spectroscopy. It is revealed that amorphous MoS2 nanograins rather than sulfur as previously suggested, are formed after delithiation, and that the fully lithiated MoS2 electrode contains additional Mo‐S related phases besides the known Mo and Li2S. Density functional theory simulations suggest that the Mo nanoparticles formed during lithiation are very reactive with Li2S, thus enabling the regeneration of MoS2 upon delithiation. These findings deepen the understanding of the lithiation/delithiation mechanism of MoS2, which will pave the way for the rational design of advanced MoS2‐based electrodes.
The structural evolutions of MoS2 during the electrochemical lithiation/delithiation process are systematically investigated using synchrotron X‐ray absorption spectroscopy and Raman spectroscopy. It is revealed that amorphous MoS2 nanograins are generated after delithiation, and the fully lithiated products involve additional Mo‐S related phases besides the known Mo and Li2S.
Self-assembly of one-dimensional nanoscale building blocks into functional three-dimensional super-structures has attracted vast interests. In current work, novel NiO flower-like architectures have ...been successfully synthesized via a facile hydrothermal method and subsequent calcination. Notably, it has been observed that the sodium oxalate plays a vital role on the aggregation of needles and a novel growth mechanism of needle-flower NiO has been proposed in detail based on the experimental results. More importantly, it is noted that the gas sensing properties of the flower-like architectures are superior to needle-like structures on the basis of the investigation. Such a synthetic way may open up an avenue to tailor the morphologies of some other metal oxides and enhance their gas sensing performance.
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•Novel needle-flower NiO architectures have been successfully synthesized.•The amount of sodium oxalate play a key role on formation of NiO 3D architectures.•Such a synthetic way may open up an avenue to enhance the gas sensing performance.
An initial Coulombic efficiency (ICE) higher than 90% is crucial for industrial lithium‐ion batteries, but numerous electrode materials are not standards compliant. Lithium trapping, due to i) ...incomplete solid‐state reaction of Li+ generation and ii) sluggish Li+ diffusion, undermines ICE in high‐capacity electrodes (e.g., conversion‐type electrodes). Current approaches mitigating lithium trapping emphasize ii) nanoscaling (<50 nm) to minimize Li+ diffusion distance, followed by severe solid electrolyte interphase formation and inferior volumetric energy density. Herein, this work accentuates i) instead, to demonstrate that the lithium trapping can be mitigated by boosting the solid‐state reaction reactivity. As a proof‐of‐concept, ternary LiFeO2 anodes, whose discharged products contain highly reactive vacancy‐rich Fe nanoparticles, can alleviate lithium trapping and enable a remarkable average ICE of ≈92.77%, much higher than binary Fe2O3 anodes (≈75.19%). Synchrotron‐based techniques and theoretical simulations reveal that the solid‐state reconversion reaction for Li+ generation between Fe and Li2O can be effectively promoted by the Fe‐vacancy‐rich local chemical environment. The superior ICE is further demonstrated by assembled pouch cells. This work proposes a novel paradigm of regulating intrinsic solid‐state chemistry to ameliorate electrochemical performance and facilitate industrial applications of various advanced electrode materials.
This work demonstrates that by boosting the intrinsic solid‐state reconversion reactivity, the lithium trapping can be effectively mitigated, thereby enhancing the initial Coulombic efficiency. This work presents novel insights into imbuing bulk materials with distinct electrochemical properties of nanomaterials and propels the commercialization of advanced electrode materials.
Nanomaterials with low-dimensional architectures frequently exhibit novel functional properties. In current work, NiO nanobelts with well-defined morphologies and uniform size have been successfully ...synthesized via a facile hydrothermal method. Furthermore, a novel growth mechanism of NiO nanobelts has been proposed in detail. Surprisingly, it is worth mentioning that the sodium oxalate is of great benefit to the formation of NiO one-dimensional nanostructures and plays a vital role on tailoring morphologies of nanobelts on the basis of further comparative experiments. Such a synthetic way may open up an avenue to prepare some other oxides.
In this work, we have successfully synthesized NiO nanobelts via a facile hydrothermal route and investigated the effect of sodium oxalate. Display omitted
•NiO nanobelts with uniform size and well-defined architectures were synthesized via a facile hydrothermal method.•A novel formation mechanism of NiO nanobelts was proposed.•The adjunction of sodium oxalate plays a key role on formation of NiO 1D architectures.•Morphologies of NiO nanobelts can be tailored by controlling the dose of sodium oxalate.
Severe capacity decay under subzero temperatures remains a significant challenge for lithium-ion batteries (LIBs) due to the sluggish interfacial kinetics. Current efforts to mitigate this ...deteriorating interfacial behavior rely on high-solubility lithium salts (e.g., Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium bis(fluorosulfonyl)imide (LiFSI))-based electrolytes to construct anion participated solvation structures. However, such electrolytes bring issues of corrosion on the current collector and increased costs. Herein, the most commonly used Lithium hexafluorophosphate (LiPF
) instead, to establish a peculiar solvation structure with a high ratio of ion pairs and aggregates by introducing a deshielding NO
additive for low-temperature LIBs is utilized. The deshielding anion significantly reduces the energy barrier for interfacial behavior at low temperatures. Benefiting from this, the graphite (Gr) anode retains a high capacity of ≈72.3% at -20 °C, which is far superior to the 32.3% and 19.4% capacity retention of counterpart electrolytes. Moreover, the LiCoO
/Gr full cell exhibits a stable cycling performance of 100 cycles at -20 °C due to the inhibited lithium plating. This work heralds a new paradigm in LiPF
-based electrolyte design for LIBs operating at subzero temperatures.
Three macrolide antibiotics (MLs, i.e., roxithromycin, clarithromycin and spiramycin) were investigated to reveal the aqueous photochemistry of the respective neutral and dissociated species (i.e., ...H2MLs+, HMLs0 and MLs−), including their susceptibility to direct photolysis as well as the hydroxyl radical (•OH) and singlet oxygen (1O2) mediated photooxidation. Under simulated sunlight (λ > 290 nm), no obvious or slow photodegradation of the three MLs were observed in pure water, while they photodegraded rapidly under shorter wavelength irradiation (λ > 200 nm). It was further found that the dependence of the kinetics on pH was attributed to the different reactivities of the dissociation species. The rate constants and cumulative light absorption increased with the order H2MLs+ < HMLs0 < MLs−. Based on competition kinetic experiments and matrix calculations, MLs− was differentiated to be more highly reactive towards •OH/1O2. The corresponding environmental half-lives were evaluated considering the reactivities and proportions of the speciated forms at different pH, indicating that 1O2 oxidation (t1O2,E = 1.83–2.53 h) contributed more than •OH oxidation (t•OH,E = 33.17–787.49 h) to the ML phototransformation in sunlit surface waters. In general, these reactions preserved the core backbone structures of the parent ML molecules and gave rise to intermediates that displayed higher toxicity to Vibrio fischeri than the parent molecules, hence demonstrating photo-modified toxicity. These results are of importance towards the goal of assessing the persistence of MLs during wastewater treatment using UV-light tertiary treatment processes, as well as in sunlit surface waters.
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•Distinct photochemistry of dissociated macrolides H2MLs+, HMLs0 and MLs− was reported.•pH dependent kinetics were attributed to increasing reactivities from H2MLs+ to MLs−.•MLs− reacted fastest towards sOH/1O2 with a key role of 1O2 in aquatic fate of MLs.•Pathways involved hydroxylation, carboxylation and cleavage of carbon-oxygen bonds.•The intermediates were more toxic to Vibrio fischeri, showing photo-modified toxicity.
Severe capacity decay under subzero temperatures remains a significant challenge for lithium‐ion batteries (LIBs) due to the sluggish interfacial kinetics. Current efforts to mitigate this ...deteriorating interfacial behavior rely on high‐solubility lithium salts (e.g., Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium bis(fluorosulfonyl)imide (LiFSI))‐based electrolytes to construct anion participated solvation structures. However, such electrolytes bring issues of corrosion on the current collector and increased costs. Herein, the most commonly used Lithium hexafluorophosphate (LiPF6) instead, to establish a peculiar solvation structure with a high ratio of ion pairs and aggregates by introducing a deshielding NO3− additive for low‐temperature LIBs is utilized. The deshielding anion significantly reduces the energy barrier for interfacial behavior at low temperatures. Benefiting from this, the graphite (Gr) anode retains a high capacity of ≈72.3% at −20 °C, which is far superior to the 32.3% and 19.4% capacity retention of counterpart electrolytes. Moreover, the LiCoO2/Gr full cell exhibits a stable cycling performance of 100 cycles at −20 °C due to the inhibited lithium plating. This work heralds a new paradigm in LiPF6‐based electrolyte design for LIBs operating at subzero temperatures.
The dilemma of solvation chemistry control for Lithium hexafluorophosphate (LiPF6)‐based low‐temperature electrolytes is tackled by introducing deshielding anions. As a proof‐of‐concept, the NO3− is chosen. Graphite anodes exhibit enhanced capacity retention of ≈72.3% at −20 °C than the counterpart electrolyte (32.3%). This strategybypasses the solubility limitation of commonly used LiPF6 and enable its application under extreme conditions.
In this work, we reported successful synthesis of SnO
2
nanocubes and nanospheres via a facile hydrothermal technique. The as-obtained SnO
2
nanostructures have been characterized by X-ray ...diffraction and field-emission scanning electron microscopy. The formation mechanism of aforementioned SnO
2
nanostructures has been proposed in detail, especially SnO
2
nanaocubes, which has been systematically investigated by varying the reaction time and the surfactant SDS play a key role in growth process of nanocubes. Furthermore, the gas sensing properties of as-prepared SnO
2
nanostructures have been tested towards ethanol. Interestingly, it is noted that gas sensing performance of nanocubes are superior to nanospheres, which certified that the gas sensing properties can be enhanced by controlling the morphologies and the SnO
2
nanocubes maybe a promising candidate based materials in the fields of gas sensors.
Monodisperse NiO hierarchical nanoflowers fabricated by nanobundles have been successfully synthesized under hydrothermal conditions followed by a calcination treatment. It is amazingly observed that ...the bundle-like nanoflowers possessed the emanative needle-like ends on the nanoscale, which was different from the previous 3D hierarchical architectures only fabricated by nanosheets, entire solid rod-like and emanative needle-like structures. Furthermore, based on the further experiments, the amount of ethylene glycol (EG, 99.5wt%) play a key role on the formation of emanative needle-like ends and constructions of the 3D hierarchical flower-like architectures, and the relative formation mechanism was primarily discussed. Such an unexpected morphology may provide a non-trivial behavior driven by the properties of emanative needle-like ends and electron transformation continuity.
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•NiO flower-like architectures fabricated by 1D nanobundle have been synthesized.•The hierarchical architectures can be tailored by varying the amount of ethylene glycol.•Such an unexpected morphology may provide a non-trivial behavior.
