High‐energy Li‐rich layered cathode materials (≈900 Wh kg−1) suffer from severe capacity and voltage decay during cycling, which is associated with layered‐to‐spinel phase transition and oxygen redox ...reaction. Current efforts mainly focus on surface modification to suppress this unwanted structural transformation. However, the true challenge probably originates from the continuous oxygen release upon charging. Here, the usage of dielectric polarization in surface coating to suppress the oxygen evolution of Li‐rich material is reported, using Mg2TiO4 as a proof‐of‐concept material. The creation of a reverse electric field in surface layers effectively restrains the outward migration of bulk oxygen anions. Meanwhile, high oxygen‐affinity elements of Mg and Ti well stabilize the surface oxygen of Li‐rich material via enhancing the energy barrier for oxygen release reaction, verified by density functional theory simulation. Benefited from these, the modified Li‐rich electrode exhibits an impressive cyclability with a high capacity retention of ≈81% even after 700 cycles at 2 C (≈0.5 A g−1), far superior to ≈44% of the unmodified counterpart. In addition, Mg2TiO4 coating greatly mitigates the voltage decay of Li‐rich material with the degradation rate reduced by ≈65%. This work proposes new insights into manipulating surface chemistry of electrode materials to control oxygen activity for high‐energy‐density rechargeable batteries.
A dielectric inverse spinel‐structured Mg2TiO4 coating on Li‐rich cathode material significantly suppresses the continuous oxygen release, endowing batteries with remarkable cyclability and well‐inhibited voltage decay, e.g., showing a capacity retention of ≈81% and voltage degradation of only 151 mV after 700 cycles, far superior to 44% and 432 mV of the unmodified counterpart.
The photochemistry of organic contaminants present in ice is receiving growing attention, given the wide presence of ice during winter in temperate regions as well as Polar and mountain environments. ...Differences between ice photochemistry and aqueous photochemistry, however, influence the quantitative fate and transformation of organic chemicals present in freshwater, marine and ice-cap environments and these differences need to be explored. Here we comparatively studied the ice and aqueous photochemistry of three antibiotics levofloxacin (LVX), sulfamerazine (SM), and chlortetracycline (CTC) under the same simulated sunlight (λ > 290 nm). Their photodegradation in ice/water followed pseudo-first-order kinetics, whereby the photolytic rates of LVX in ice and water were found to be similar, SM photodegraded faster in ice, while CTC underwent slower photodegradation in ice. Whether individual antibiotics underwent faster photodegradation in ice or not depends on the specific concentration effect and cage effect coexisting in the ice compartment. In most cases, the fastest photodegradation occurred in freshwater ice or in fresh water, and the slowest photolysis occurred in pure-water ice or in pure water. This can be attributed to the effects of key photochemical reactive constituents of Cl−, HA, NO3− and Fe(III), that exist in natural waters. These constituents at certain levels showed significant effects (P < 0.1) on the photolysis, not only in ice but also in water. However, these individual constituents at a given concentration, serve to either enhance or suppress the photoreaction, depending on the specific antibiotic and the matrix type (e.g., ice or aqueous solution). Furthermore, extrapolation of the laboratory findings to cold environments indicate that pharmaceuticals present in ice will have a different photofate compared to water. These results are of particular relevance for those regions that experience seasonal ice cover in fresh water and coastal marine systems.
Environmental photochemistry of antibiotics in ice and in water. Display omitted
•It is a detailed comparison of the ice and aqueous photochemistry of antibiotics.•Similarities and differences of the photodegradation in ice and in water are revealed.•The order of photodegradation rates differs in the two phases of different waters.•Reaction matrix and water constituents have an obvious impact on photolytic kinetics.•Photochemical fate of antibiotics depends on the reaction media, latitudes and seasons.
The presence of antibiotics as emerging micropollutants in the aquatic environment has been raising health concerns for a number of years. Macrolides (MLs) are a large class of widely-used ...antibiotics, but there is a lack of information on their distribution and risks in surface waters across the central and western regions of China. To clearly describe the pollution characteristics and risks of MLs in Weihe River (the largest tributary of the Yellow River), analysis of 5 typical MLs was conducted using a newly developed LC−MS/MS method for 50 water samples collected over three seasons during 2021–2022. The results revealed that the area showed comparable ML concentrations with other regions worldwide. However, the ML concentrations were much lower than those in the river during 2016 from a previous study. Furthermore, concentrations exhibited significant seasonal variation, with highest concentrations in the winter. Along the main stream of the Weihe River, the sampling sites close to the wastewater treatment plants (WWTPs) and livestock farms exhibited higher concentrations of MLs, indicating the significant contribution from WWTPs and animal husbandry to the emission of MLs. The risk quotients (RQs) suggested that the ecological risks associated with MLs were most pronounced in winter among the three seasons, with erythromycin posing a high or medium risk to algae at all sampling sites. The results of this study will be of importance towards the goal of understanding the presence of these emerging contaminants in surface waters and any required risk reduction measures.
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•Distribution and risks were revealed for macrolide antibiotics (MLs) in Weihe River.•Total 50 surface water samples were collected and analyzed in three seasons.•The ML concentration exhibited significant seasonal variation.•The sites near WWTPs and livestock farms exhibited high ML concentration.•The ecological risks of MLs in winter were highest among the three seasons.
Here we report a simple hydrothermal route for the preparation of CuO nano-flower which has been proved to exhibit good performances in gas-sensing. We concentrate on the microstructure and ...morphology of CuO by adjusting the reaction time length. Four different morphologies that formed a flower-like shape with a diameter of 1–3 µm were obtained. The CuO nanostructures were characterized in detail by means of X-ray diffraction and scanning electron microscopy and were apparently seen that they were composed of abundant aggregative nanobelts. The prepared CuO properties in gas-sensing were also measured in our experiments. In addition, a proper growth mechanism was proposed based on the results. Moreover, the CuO nano-flowers may resolve the difficulties in low-dimensional gas-sensing applications after more research having been conducted.
Rate capability is characterized necessarily in almost all battery-related reports, while there is no universal metric for quantitative comparison. Here, we proposed the characteristic time of ...diffusion, which mainly combines the effects of diffusion coefficients and geometric sizes, as an easy-to-use figure of merit (FOM) to standardize the comparison of fast-charging battery materials. It offers an indicator to rank the rate capabilities of different battery materials and suggests two general methods to improve the rate capability: decreasing the geometric sizes or increasing the diffusion coefficients. Based on this FOM, more comprehensive FOMs for quantifying the rate capabilities of battery materials are expected by incorporating other processes (interfacial reaction, migration) into the current diffusion-dominated electrochemical model. Combined with Peukert’s empirical law, it may characterize rate capabilities of batteries in the future.
In this study, a systematic monitoring campaign of 30 antibiotics belonging to tetracyclines (TCs), macrolides (MLs), fluoroquinolones (FQs) and sulfonamides (SAs) was performed in the Xi'an section ...of the Wei River during three sampling events (December 2021, June 2022, and September 2022). The total concentrations of antibiotics in water ranged from 297 to 461 ng/L with high detection frequencies ranging from 45% to 100% for the various antibiotics. A marked seasonal variation in concentrations was found with total antibiotic concentrations in winter being 1.5 and 2 times higher than those in the summer and autumn seasons, respectively. The main contaminants in both winter and summer seasons were FQs, but in the autumn SAs were more abundant, suggesting different seasonal sources or more effective runoff for certain antibiotics during periods of rainfall. Combined analysis using redundancy and clustering analysis indicated that the distribution of antibiotics in the Wei River was affected by the confluence with dilution of tributaries and outlet of domestic sewage. Ecological risk assessment based on risk quotient (RQ) showed that most antibiotics in water samples posed insignificant risk to fish and green algae, as well as insignificant to low risk to Daphnia. The water-sediment distribution coefficients of SAs were higher than those of other antibiotics, indicating that particle-bound runoff could be a significant source for this class of antibiotics.
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•A total of 30 antibiotics were monitored in Wei River during 2021–2022.•The total concentrations were higher in the winter than in other seasons.•Significant tributary dilution on the concentrations of antibiotics was observed.•Ecological risk of antibiotics exposing to trophic levels was assessed at a low level.
•The complex affinity with FQs has an order of Fe(III) > Cu(II) > Al(III).•Photochemistry properties of FQs were affected by metal complexation.•FQs-Cu(II) complex was verified by FTIR and theory of ...electrostatic potential.•Significant changes in toxicity of antibiotics were found after metal coordination.
Acid-base dissociable antibiotic-metal complexes are known to be emerging contaminants in the aquatic environments. However, little information is available on the photochemical properties and toxicity of these complex forms. This study investigated the spectral properties of three fluoroquinolones (FQs) with and without metal ions Fe(III), Cu(II), and Al(III) in solutions under different pH conditions, as well as evaluated the changes in toxicity due to the complex with these metal ions using luminescent bacteria (vibrio fischeri). FQs showed a higher tendency to coordinate metal ions under alkaline conditions compared to neutral and acidic conditions, and the formation of complexes weakened the ultraviolet-absorbing ability of FQs. At pH = 7.0, Cu(II) quenched the fluorescence intensity of FQs. Moreover, their Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were explored, revealing that the coordination sites of Cu(II) in three FQs were situated in a bidentate manner through the oxygen atom of the deprotonated carboxyl group and cyclic carbonyl oxygen atom. This conclusion was further verified by the theory of molecular surface electrostatic potential. In addition, except for complexes of ciprofloxacin-metals, enhanced toxicity of FQs upon coordination with Fe(III) was observed, while reduced toxicity was found for coordination with Cu(II) and Al(III). These results are important for accurately evaluating the photochemical behavior and risk of these antibiotics in aquatic environments contaminated with metal ions.
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The Antarctic ecosystem is characterized by few consumer species and simple trophic levels (TLs), rendering it an ideal setting to investigate the environmental behavior of contaminants. The paper ...aims to assess the presence, sources and biomagnification behavior of polycyclic aromatic hydrocarbons (PAHs) of the Antarctic food web and is the first study of biomagnifications of PAHs in the Fildes Peninsula in Antarctica. Nine representative species from the Fildes Peninsula in Antarctica were sampled and evaluated for PAH presence. PAH concentrations ranged from 477.41 to 1237.54 ng/g lipid weight (lw) in the sampled Antarctic biota, with low molecular weight PAHs (naphthalene, acenaphthylene, acenaphthene, and fluorene) comprising the majority of the PAHs. PAHs concentrations were negatively correlated with TLs. Further, the food web magnification factor (FWMF) of ∑PAHs was 0.63, suggesting biodilution of PAHs along the TLs. Source analyses revealed that the PAHs mainly originated from petroleum contamination and the combustion of fossil fuels.
New antibiotic contaminants have been detected in both surface waters and natural ice across cold regions. However, few studies have revealed distinctions between their ice and aqueous ...photochemistry. In this study, the photodegradation and effects of the main dissolved substances on the photolytic kinetics were investigated for sulfonamides (SAs) and fluoroquinolones (FQs) in ice/water under simulated sunlight. The results showed that the photolysis of sulfamethizole (SMT), sulfachloropyridazine (SCP), enrofloxacin (ENR) and difloxacin (DIF) in ice/water followed the pseudo-first-order kinetics with their quantum yields ranging from 4.93 × 10−3 to 11.15 × 10−2. The individual antibiotics experienced disparate photodegradation rates in ice and in water. This divergence was attributed to the concentration-enhancing effect and the solvent cage effect that occurred in the freezing process. Moreover, the main constituents (Cl−, HASS, NO3− and Fe(III)) exhibited varying degrees of promotion or inhibition on the photodegradation of SAs and FQs in the two phases (p < 0.05), and these effects were dependent on the individual antibiotics and the matrix. Extrapolation of the laboratory data to the field conditions provided a reasonable estimate of environmental photolytic half-lives (t1/2,E) during midsummer and midwinter in cold regions. The estimated t1/2,E values ranged from 0.02 h for ENR to 14 h for SCP, which depended on the reaction phases, latitudes and seasons. These results revealed the similarities and differences between the ice and aqueous photochemistry of antibiotics, which is important for the accurate assessment of the fate and risk of these new pollutants in cold environments.
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•Photochemical behavior of new antibiotic pollutants was compared in ice and in water.•The concentration-enhancing and cage effects result in different photolytic kinetics.•The effects of main constituents depended on the specific antibiotic and the matrix.•The lab data were extrapolated to cold regions to evaluate photo fate of antibiotics.•Ice photodegradation may be important for antibiotics in winter at high latitudes.
Flexible electrodes that are multilayer, multimaterial, and conformal are pivotal for multifunctional wearable electronics. Traditional electronic circuits manufacturing requires substrate‐supported ...transfer printing, which limits their multilayer integrity and device conformability on arbitrary surfaces. Herein, a “shrinkage‐assisted patterning by evaporation” (SHAPE) method is reported, by employing evaporation‐induced interfacial strain mismatch, to fabricate auto‐detachable, freestanding, and patternable electrodes. The SHAPE method utilizes vacuum‐filtration of polyaniline/bacterial cellulose (PANI/BC) ink through a masked filtration membrane to print high‐resolution, patterned, and multilayer electrodes. The strong interlayer hydrogen bonding ensures robust multilayer integrity, while the controllable evaporative shrinking property of PANI/BC induces mismatch between the strains of the electrode and filtration membrane at the interface and thus autodetachment of electrodes. Notably, a 500‐layer substrateless micro‐supercapacitor fabricated using the SHAPE method exhibits an energy density of 350 mWh cm−2 at a power density of 40 mW cm−2, 100 times higher than reported substrate‐confined counterparts. Moreover, a digital circuit fabricated using the SHAPE method functions stably on a deformed glove, highlighting the broad wearable applications of the SHAPE method.
A “shrinkage‐assisted patterning by evaporation” (SHAPE) method is reported to fabricate freestanding and flexible electrodes. The multimaterial, multilayer, and shape‐designable properties of the SHAPE method for fabrication of flexible electrodes provide electronics with unconfined stacking, customizable stretchability, and conformable integration on arbitrary surfaces, demonstrating their wide spectrum of applications in wearable and 3D integrated electronics.
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