Sustainable Electrolytes: Design Principles and Recent Advances.

Today, rechargeable batteries are omnipresent and essential for our existence. In order to improve the electrochemical performance of electric fields, the introduction of electrolytes with fluorine (F)-based inorganic elemental compositions is a direction of exploration. However, most fluorocarbons have a high global warming potential and ozone depletion potential, which do not meet the sustainability requirements of the battery industry. Therefore, developing sustainable electrolytes is a viable option for future battery development. Although researchers have made much progress in electrolyte optimization, little attention has been paid to developing low-toxic and safe electrolytes. This review aims to elucidate the design principles and recent advances in this direction for solvents and salts. It concludes with a summary and outlook on future research directions for the molecular design of green electrolytes for practical high-voltage rechargeable batteries.

Fabrication of fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots coupled with smartphone readout for tyramine determination in fermented meat products.

A fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots (r-BCDs@MIPs) was developed to detect tyramine in fermented meat products. The red emissive biomass-derived carbon dots (r-BCDs) were synthesized by the one-step solvothermal method using discarded passion fruit shells as raw materials. The fluorescence emission peak of r-BCDs was at 670 nm, and the relative quantum yield (QY) was about 2.44%. Molecularly imprinted sensing materials were prepared with r-BCDs as fluorescent centers for the detection of trace tyramine, which showed a good linear response in the concentration range of tyramine from 1 to 40 µg L-1. The linear correlation coefficient was 0.9837, and the limit of detection was 0.77 µg L-1. The method was successfully applied to the determination of tyramine in fermented meat products, and the recovery was 87.17-106.02%. The reliability of the results was verified through high-performance liquid chromatography (HPLC). Furthermore, we combined the r-BCDs@MIPs with smartphone-assisted signal readout to achieve real-time detection of tyramine in real samples. Considering its simplicity and convenience, the method could be used as a rapid and low-cost promising platform with broad application prospects for on-site detection of trace tyramine with smartphone-assisted signal readout.

Nonflammable Phosphate-Based Electrolyte for Safe and Stable Potassium Batteries Enabled by Optimized Solvation Effect.

Current potassium-ion batteries (PIBs) are limited in safety and lifetime owing to the lack of suitable electrolyte solutions. To address these issues, herein, we report an innovative non-flammable electrolyte design strategy that leverages an optimal moderate solvation phosphate-based solvent which strikes a balance between solvation capability and salt dissociation ability, leading to superior electrochemical performance. The formulated electrolyte simultaneously exhibits the advantages of low salt concentration (only 0.6 M), low viscosity, high ionic conductivity, high oxidative stability, and safety. Our electrolyte also promotes the formation of self-limiting inorganic-rich interphases at the anode surface, alongside robust cathode-electrolyte interphase on iron-based Prussian blue analogues, mitigating electrode/electrolyte side reactions and preventing Fe dissolution. Notably, the PIBs employing our electrolyte exhibit exceptional durability, with 80 % capacity retention after 2,000 cycles at high-voltage of 4.2 V in a coin cell. Impressively, in a larger scale pouch cell, it maintains over 81 % of its initial capacity after 1,400 cycles at 1 C-rate with high average Coulombic efficiency of 99.6 %. This work represents a significant advancement toward the realization of safe, sustainable, and high-performance PIBs.

Energy-efficient Preparation of Amino and Sulfhydryl Functionalized Biomass Carbon Dots via a Reverse Microemulsion for Specific Recognition of Fe3+ and L-cysteine.

Amino- and sulfhydryl- functionalized biomass carbon dots (BCDs) were prepared by one-pot reverse microemulsion for specific recognition of ferric ions (Fe3+) and L-cysteine (L-Cys). Green grapefruit peel was used as the carbon source while aminosilane and mercaptosilane were used as N- and S-supplier. Following the adsorption of Fe3+ on the surfaces of BCDs-NH2 and BCDs-SH, the fluorescence responses was quenched step by step, while adding L-Cys to the BCDs-NH2/Fe3+ system restored the fluorescence. The BCDs-NH2 and BCDs-SH system exhibited extremely low limits of detection for Fe3+ of 3.2 and 3.0 nM, respectively, within a wide linear ranges of 0.006-200 µM and 0.004-200 µM, respectively. The BCDs-NH2/Fe3+ systems were used as an optosensor for L-Cys in the concentration ranges of 0.08-30 and 30-1000 µM with a detection limit of 65 nM. Developed BCDs-NH2 and BCDs-SH were able to respond to Fe3+ in water samples with satisfactory recoveries of 100.1%-103.1% and 94.6%-108.5%, respectively, and the BCDs-NH2/Fe3+ system was also able to respond to BCDs-NH2/Fe3+ in actual lake water samples with recoveries from 87.3% to 98.8%. Meanwhile, The BCDs-NH2 exhibited good photoluminescence and stability, and the with a fluorescence quantum yield was as high as 25%. This work demonstrates the feasibility of using such materials to remove hazardous ions from water and employing the resulting complexes for optosensing in a sustainable manner.

Variations in dissolved oxygen and aquatic biological responses in China's coastal seas.

Coastal areas can represent an ecological transition zone with the function of biodiversity conservation, and good water quality is fundamental to maintaining this function. In this study, we analyzed data from 2011 to 2020 to reveal the variation in dissolved oxygen (DO) and the aquatic biological response in China's coastal seas. Results showed that DO in coastal waters exhibited an upward trend from 2011 to 2020 because of reduction in terrestrial anthropogenic pollutant (TAP) input. In comparison with DO in other seas, the DO content in the East China Sea was lower owing to higher TAP input, i.e., the proportion of DO of <5 mg L-1 accounted for approximately 60% of the total. Species numbers, density, and the species diversity index of phytoplankton, zooplankton, and macrobenthos were different in the different sea areas because phytoplankton, zooplankton, and macrobenthos have different responses to changes in DO. In comparison with the species numbers of zooplankton and macrobenthos, the species numbers of phytoplankton were more significantly related to DO, and showed a negative linear relationship with a better DO environment (DO ≥ 5 mg L-1; r2 = 0.39, p < 0.01) and positive correlation with a poor DO environment (DO < 3 mg L-1; r2 = 0.52, p < 0.01). A better DO environment is conducive to increased density of macrobenthos. Studies have shown that a good DO environment contributes to coastal ecosystem health, and continuous control of TAP input is an effective means of ensuring DO recovery.

Green Ether Electrolytes for Sustainable High-voltage Potassium Ion Batteries.

Ether-based electrolytes are promising for secondary batteries due to their good compatibility with alkali metal anodes and high ionic conductivity. However, they suffer from poor oxidative stability and high toxicity, leading to severe electrolyte decomposition at high voltage and biosafety/environmental concerns when electrolyte leakage occurs. Here, we report a green ether solvent through a rational design of carbon-chain regulation to elicit steric hindrance, such a structure significantly reducing the solvent's biotoxicity and tuning the solvation structure of electrolytes. Notably, our solvent design is versatile, and an anion-dominated solvation structure is favored, facilitating a stable interphase formation on both the anode and cathode in potassium-ion batteries. Remarkably, the green ether-based electrolyte demonstrates excellent compatibility with K metal and graphite anode and a 4.2 V high-voltage cathode (200 cycles with average Coulombic efficiency of 99.64 %). This work points to a promising path toward the molecular design of green ether-based electrolytes for practical high-voltage potassium-ion batteries and other rechargeable batteries.

Carbon Quantum Dots from Pomelo Peel as Fluorescence Probes for "Turn-Off-On" High-Sensitivity Detection of Fe3+ and L-Cysteine.

This study designed a "turn-off-on" fluorescence analysis method based on carbon quantum dots (CQDs) to detect metal ions and amino acids in real sample systems. CQDs were derived from green pomelo peel via a one-step hydrothermal process. The co-doped CQDs with N and S atoms imparted excellent optical properties (quantum yield = 17.31%). The prepared CQDs could be used as fluorescent "turn-off" probes to detect Fe3+ with a limit of detection of 0.086 µM, a linear detection range of 0.1-160 µM, and recovery of 83.47-106.53% in water samples. The quenched CQD fluorescence could be turned on after adding L-cysteine (L-Cys), which allowed detection of L-Cys with a detection limit of 0.34 µM and linear range of 0.4-85 µM. Recovery of L-Cys in amino acid beverage was 87.08-122.74%. Visual paper-based testing strips and cellulose/CQDs composite hydrogels could be also used to detect Fe3+ and L-Cys.

An ionic liquid-assisted quantum dot-grafted covalent organic framework-based multi-dimensional sensing array for discrimination of insecticides using principal component analysis and clustered heat map.

A robust multi-dimensional sensing array based on VBimBF4B/MAA-anchored quantum dot (QD)-grafted covalent organic frameworks (COFs) [(V-M)/QD-grafted COFs] was established via one-pot strategy. The multi-dimensional sensing array has the outstanding advantages of physicochemical and thermal stability, large specific surface area, and regular pore structures. The assistance of ionic liquid VBimBF4B enhanced the transduction efficiency, and the synergistic effect of COFs enhanced detection efficiency. The improved multi-dimensional sensing array by COFs and ionic liquid VBimBF4B served to identify seven insecticides by non-specific interactions via hydrogen bonding, and the differences in the kinetics of the binding to the insecticides resulted in variation of the three-output channel (fluorescence, phosphorescence, and light scattering) signals, thus generating a distinct optical fingerprint. The unique fingerprint patterns of seven kinds of common insecticides at 200 µg L-1 were successfully discriminated using principal component analysis and clustered heat map analysis. The multi-dimensional sensing array showed a response to seven insecticides based on three spectral channels over the range of 0.001-0.4 µg mL-1 with a limit of detection of 1.08-18.68 µg L-1. The spiked recovery of tap water was 79.86-134.22%, with RSD ranging from 0.89-14.9%. This study broadens the applications of sensing arrays technology and provides a promising building block for insecticide determination.

Rapid determination of lambda-cyhalothrin using a fluorescent probe based on ionic-liquid-sensitized carbon dots coated with molecularly imprinted polymers.

A highly selective and sensitive fluorescent probe for optosensing lambda-cyhalothrin (LC) was prepared. The probe was based on sulfur-doped carbon dots (CDs) coated with molecularly imprinted polymers (MIPs). Doping the CDs with sulfur and modifying the surfaces of the CDs with an ionic liquid enhanced the performance of the fluorescent probe. The selectivity of the probe was improved through the application of molecular imprinting technology utilizing acrylamide and 1-vinyl-3-butylimidazolium tetrafluoroborate [VBIm][BF4] as functional monomers. The resulting probe was used to detect LC, which is a pesticide residue, in vegetables and tea. Under optimal detection conditions, the linear range of the probe was found to be 1-150 µg kg-1 and the limit of detection to be 0.5 µg kg-1 by analyzing excitation/emission maxima at 350/450 nm. The developed method was successfully used to determine LC in vegetables and tea, yielding recoveries of 98.90-116.93%. These results suggest that this fluorescent probe based on MIP-coated, room-temperature ionic-liquid-sensitized, sulfur-doped carbon dots has great potential to be utilized for the precise detection of LC in complex samples. Graphical abstract.

Ionic-liquid-stabilized fluorescent probe based on S-doped carbon dot-embedded covalent-organic frameworks for determination of histamine.

An ionic-liquid-stabilized fluorescent probe for histamine is described. Sulfur-doped carbon dots (S-CDs) were incorporated into a covalent organic framework (COF) that was prepared from 1,3,5-triformylphloroglucinol and 2,5-dimethyl-p-phenylenediamine by one-pot hydrothermal polymerization in the dark. The blue fluorescence of the S-CDs (with excitation/emission maxima at 350/440 nm) is enhanced (compared to undoped CDs) due to element doping by ionic-liquid modification. The COF is resistant to acids, bases, and boiling water. The fluorescence of the probe is statically quenched by histamine, and quenching follows the Stern-Volmer equation. The normalized fluorescence of the probe drops in the 10 to 1000 µg kg-1 histamine concentration range, and the limit of detection is 5.3 µg kg-1. The probe was successfully applied to the analysis of wine and fermented meat products. The recoveries from spiked samples range between 84.6 and 115.3%. The method is selective, sensitive, stable and repeatable. The mechanisms of the fluorometric response and molecular recognition were explored. Graphical abstractSchematic presentation of ionic-liquid-stabilized fluorescent probe based on S-doped carbon dot-embedded covalent organic framework for determination of histamine. The ionic liquid [VBIm][BF4] reacts with MPTS-modified carbon dots to enhance the fluorescence signal for analyte recognition.

A fluorescent nanoprobe for 4-ethylguaiacol based on the use of a molecularly imprinted polymer doped with a covalent organic framework grafted onto carbon nanodots.

An efficient and rapid fluorescent nanoprobe is described for the determination of the aroma compound 4-ethylguaiacol (4-EG). A molecularly imprinted polymer was doped with a covalent organic framework (COF) grafted onto carbon nanodots that was prepared by one-pot reverse microemulsion polymerization. Amino groups at the surface of carbon nanodots coordinate to the COFs to produce a strong bond and this warrants thermal and chemical stability of the probe. Remaining free amino groups interact with the phenolic hydroxyl groups of 4-EG through acid-base pairing interactions. The probe, with excitation/emission maxima at 350/440 nm, responds to 4-EG due to the charge transfer to the carbon nanodots. Under optimized conditions, fluorescence drops linearly as the concentrations of 4-EG increase from 0.025 to 1 µg mL-1, with a detection limit of 17 ng mL-1. The probe was applied to the determination of 4-ethylguaiacol in Chinese Baijiu and wine samples after pretreatment by a single dilution step. The recoveries of spiked samples ranged from 78.4to 110.1%. Graphical abstract Schematic presentation of the synthesis of a fluorescent nanoprobe based on molecularly imprinted polymers doped with covalent organic framework grafted onto carbon nanodots. It was used as an efficient and rapid nanoprobe for 4-ethylguaiacol detection with high selectivity and sensitivity.

Baijiu Vinasse Extract Scavenges Glyoxal and Inhibits the Formation of Nε-Carboxymethyllysine in Dairy Food.

The inhibitory effects of baijiu vinasse extract and its phenolic acid compounds on the Nε-carboxymethyllysine (CML) formation from dairy food were investigated. The inhibitory effect of the baijiu vinasse extract against CML formation was 43.2% in the casein and D-glucose model, which used 6 mL of the 70% acetone extract at 60 °C for 40 min. The HPLC-MS/MS profiles of the vinasse extract indicated that vanillic, chlorogenic, p-coumaric, sinapic, caffeic, ferulic, and syringic acids were seven major phenolic acid compounds. Furthermore, the inhibitory mechanism of the phenolic acid compounds in the model of dairy food was discussed by the trapping and scavenging of glyoxal. The results of this study exhibit that seven major antioxidant phenolic acid compounds may play important roles in the antioxidant activity and CML inhibition of the vinasse extract in a model of dairy foods.

Photostimulus-Responsive Peptide Dot-Centered Covalent Organic Polymers: Effective Pesticide Sensing via Enhancing Accessibility.

Pesticide detection and monitoring are necessary for human health as the overapplication has serious consequences for environmental pollution. Herein, a proper modulation strategy was implemented to construct the photostimulus-responsive peptide-dot-centered covalent organic polymer (P-PCOP) nanoarchitecture for selective sensing of pesticides. The as-constructed P-PCOP was prepared at room temperature by using amino-containing peptide dots as a building block instead of common organic molecules, and the merits of P-PCOP enable it to reduce the steric hindrance of recognition, enhance the interfacial contact of the target, and facilitate the accessibility of sites, which promises to improve the sensitivity. The P-PCOF exhibited a low detection limit of 0.38 µg L-1 to cartap over the range of 1-80 µg L-1 (R2 = 0.9845), and the recoveries percentage in real samples was estimated to be 93.39-105.82%. More importantly, the DFT calculation confirmed the selective recognition ability of P-PCOP on chemical pesticides. In conjunction with a smartphone-integrated portable reading device, on-site chemical sensing is achieved. The proper modulation strategy of fixing a functional guest on the COP system contributes to the advanced structure-chemical properties that are conducive to their applications in chemical sensing.

Fast detection of tryptamine in meat products with azide-functionalized covalent organic frameworks confined in molecularly imprinted polymers.

Tryptamine is a biogenic amine that affects organoleptic quality through the generation of off-odours in foods. Herein, imine-based covalent organic frameworks (COFs) were synthesized via Schiff base reactions and postmodified with click chemistry to generate azide-functionalized COFs with tunable azide units on the walls. The combination of molecular imprinting with COFs enabled the specific recognition of the targets. The resulting optosensing system (azide-functionalized COFs@MIPs) was used as a sample-to-answer analyser for detecting tryptamine (detection time within 10 min). A linear relationship was observed for the fluorescence response to tryptamine concentrations in the range of 3-120 µg L-1, with a limit of detection of 1.74 µg L-1. The recoveries for spiked samples were satisfactory, with relative standard deviations <9.90%. The optosensing system is a potential tool for the quantitative detection of tryptamine in meat products because of its lower cost, shorter processing time, and simpler processing steps compared to conventional chromatographic techniques.

Conjugated molecularly imprinted polymers based on covalent organic frameworks: Fluorescent sensing platform for specific capture of urea and elimination of ethyl carbamate.

This study described the preparation of an azide covalent organic framework-embedded molecularly imprinted polymers (COFs(azide)@MIPs) platform for urea adsorption and indirect ethyl carbamate (EC) removal from Chinese yellow rice wine (Huangjiu). By modifying the pore surface of COFs using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, COFs(azide) with a high fluorescence quantum yield and particular recognition ability were inventively produced. In order to selectively trap urea, the COFs(azide) were encased in an imprinted shell layer via imprinting technology. With a detection limit (LOD) of 0.016 µg L-1 (R2 = 0.9874), the COFs(azides)@MIPs demonstrated a good linear relationship with urea in the linear range of 0-5 µg L-1. Using real Huangjiu samples, the spiking recovery trials showed the viability of this sensing platform with recoveries ranging from 88.44 % to 109.26 % and an RSD of less than 3.40 %. The Huangjiu processing model system achieved 38.93 % EC reduction by COFs(azides)@MIPs. This research will open up new avenues for the treatment of health problems associated with fermented alcoholic beverages, particularly Huangjiu, while also capturing and removing hazards coming from food.

A smartphone-combined ratiometric fluorescence molecularly imprinted probe based on biomass-derived carbon dots for determination of tyramine in fermented meat products.

A ratiometric fluorescence molecularly imprinted probe employing two distinct emission wavelengths of biomass carbon dots was developed for highly selective and visual quantitative detection of tyramine in fermented meat products. The red emission biomass carbon dots were employed as responsive elements, and the blue ones were utilized as the reference elements. The molecularly imprinted polymers were incorporated in the ratiometric sensing to distinguish and adsorb tyramine. With the linear range of 1-60 µg/L, the ratiometric fluorescence molecularly imprinted probe was successfully applied to detect tyramine in real samples with the satisfactory recoveries of 79.74-112.12% and the detect limitation of 1.3 µg/kg, indicating that this probe has great potential applications for the detection of tyramine in real samples. Moreover, smartphone-based fluorescence signal recognition analysis on hand has been developed for the quantitative analysis of tyramine, providing a portable visual optical analysis terminal for rapid on-site determination of tyramine.

Restructuring Electrolyte Solvation by a Partially and Weakly Solvating Cosolvent toward High-Performance Potassium-Ion Batteries.

Ether-based electrolytes are among the most important electrolytes for potassium-ion batteries (PIBs) due to their low polarization voltage and notable compatibility with potassium metal. However, their development is hindered by the strong binding between K+ and ether solvents, leading to [K+-solvent] cointercalation on graphite anodes. Herein, we propose a partially and weakly solvating electrolyte (PWSE) wherein the local solvation environment of the conventional 1,2-dimethoxyethane (DME)-based electrolyte is efficiently reconfigured by a partially and weakly solvating diethoxy methane (DEM) cosolvent. For the PWSE in particular, DEM partially participates in the solvation shell and weakens the chelation between K+ and DME, facilitating desolvation and suppressing cointercalation behavior. Notably, the solvation structure of the DME-based electrolyte is transformed into a more cation-anion-cluster-dominated structure, consequently promoting thin and stable solid-electrolyte interphase (SEI) generation. Benefiting from optimized solvation and SEI generation, the PWSE enables a graphite electrode with reversible K+ (de)intercalation (for over 1000 cycles) and K with reversible plating/stripping (the K||Cu cell with an average Coulombic efficiency of 98.72% over 400 cycles) and dendrite-free properties (the K||K cell operates over 1800 h). We demonstrate that rational PWSE design provides an approach to tailoring electrolytes toward stable PIBs.

Fluorescent Molecularly Imprinted Polymers Loaded with Avenanthramides for Inhibition of Advanced Glycation End Products.

Encapsulating bioactive avenanthramides (AVAs) in carriers to respond to the environmental changes of food thermal processing allows the controlled release of AVAs for the effective inhibition of biohazards. In this study, fluorescent molecular imprinted polymers (FMIPs) loaded with AVAs were prepared by reverse microemulsion. The fluorescent signal was generated by carbon dots (CDs), which were derived from oat bran to determine the load of AVAs. The FMIPs were uniformly spherical in appearance and demonstrated favorable properties, such as thermal stability, protection of AVAs against photodegradation, high encapsulation efficiency, and effective scavenging of free radicals. After consideration of the different kinetics models, the release of AVAs from the FMIPs matched the Weibull model and followed a Fickian diffusion mechanism. The FMIPs exhibited good inhibition of pyrraline in a simulated casein-ribose system and in milk samples, indicating the release of AVAs could inhibit the generation of pyrraline.

Dandelion-like covalent organic frameworks with high-efficiency fluorescence for ratiometric sensing and visual tracking-by-detection of Fe3.

Iron ions, one of the most common heavy metal pollutants in industrial waste materials, are continuously actively or passively delivered to the environment. Meanwhile, the importance of Fe3+ in biological processes in vivo can not be neglected due to its crucial role in maintaining normal physiological function. Therefore, a ratiometric fluorescence covalent organic framework (TD-COF) was constructed for tracking-by-detection of Fe3+. Alkynes-extended 1,3,6,8-tetrakis(4-ethynyl benzaldehyde)-pyrene (TEBPY) with complete planar structure and 2,5-dihydroxyterephthalohydrazide (DHTH) with functional group -OH were selected as the building blocks. The ratiometric fluorescence TD-COF with a dandelion-like structure exhibited its dual emission peaked at 510 nm and 630 nm. It displayed an obvious fluorescence color variation of yellow-red-black in the presence of Fe3+. Benefiting from the high luminescent efficiency (QY of 36.4%) and multiple identical binding sites, TD-COF exhibited a wide linear range to Fe3+ (0.005-50 µM) with a detection limit of 10.9 nM. Additionally, a smartphone visual sensing platform integrated with TD-COF was developed based on the color transformation and successfully applied to visual smart real-time monitoring Fe3+. More surprisingly, the maximum adsorption capacity of TD-COF towards Fe3+ was 833.3 mg/g due to the coordination interaction and cationic π-effect. The practicability of the smartphone-integrated ratiometric sensing platform for visual tracking-by-detection of Fe3+ was verified by choosing tap water as the actual sample, and the recoveries were calculated to be 98.71-100.88%. This work thus developed COF-based ratiometric sensing of Fe3+, which is an attractive candidate for further application in fluorescent sensing and visual monitoring.

Peptide-Based Molecularly Imprinted Polymer: A Visual and Digital Platform for Specific Recognition and Detection of Ethyl Carbamate.

A visual and digital platform was constructed by peptide-based molecularly imprinted polymers (PMIPs) for specific recognition and detection of ethyl carbamate (EC). Here, the optosensing core was creatively constructed by the covalent assembly of dipeptides (H-Phe-Phe-OH) and genipin biomolecules for high fluorescence quantum yield and dual-signal response capability. MIPs were wrapped in the shell of the optosensing core for selectivity of EC from actual samples of alcoholic beverages. The genipin-FF nanoparticles (GFPNs)@PMIPs exhibited dual-band red-blue fluorescence image with a low detection limit of 0.817 and 1.65 µg L-1, respectively, in the optimal linear range of 2-240 µg L-1. The accuracy of this method was verified by the spiked recovery experiment, and a good recovery from 83.97 to 106.75% of the proposed optosensing method was obtained. In addition, a smartphone application was coupled with GFPNs@PMIPs to realize online real-time detection of EC. With the addition of EC, the color change of G and B values was negligible compared with the R value. This work also provides a potential method for on-site visual detection of analytes.