Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-s...Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-satellite SERS aptasensor was constructed by combining aptamer-decorated Fe_(3)O_(4)@Au MNPs(as the recognize probe for histamine)and complementary DNA-modified silver nanoparticles carrying 4-mercaptobenzonitrile(4-MBN)(Ag@4-MBN@Ag-c-DNA)as the SERS signal probe for the indirect detection of histamine.Under an applied magnetic field in the absence of histamine,the assembly gave an intense Raman signal at“Raman biological-silent”region due to 4-MBN.In the presence of histamine,the Ag@4-MBN@Ag-c-DNA SERS-tag was released from the Fe_(3)O_(4)@Au MNPs,thus decreasing the SERS signal.Under optimal conditions,an ultra-low limit of detection of 0.65×10^(-3)ng/mL and a linear range 10^(-2)-10^5 ng/mL on the SERS aptasensor were obtained.The histamine content in four food samples were analyzed using the SERS aptasensor,with the results consistent with those determined by high performance liquid chromatography.The present work highlights the merits of indirect strategies for the ultrasensitive and highly selective SERS detection of small biological molecules in complex matrices.展开更多
For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin a...For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas.To date,the synthesis of catalysts that are both ultrathin(monolayer)and ultrafine(lateral size<10nm)has proven extremely challenging.Herein,using a facile ultrasonic exfoliation procedure,we describe the successful synthesis of ultrafine ZnCo-LDH nanosheets(denoted as ZnCo-UF)with a size^3.5 nm and thickness^0.5 nm.The single layer ZnCo-UF nanosheets possess an abundance of oxygen vacancies(Vo)and unsaturated coordination s让es,thereby affording outstanding electrocatalytic water oxidation performance.DFT calculations confirmed that Vo on the surface of ZnCo-UF enhanced H20 adsorption via increasing the electropositivity of the nanosheets.展开更多
Fermented foods represent an important segment of current food markets,especially traditional or ethnic food markets.The demand for efficient utilization of agrowastes,together with advancements in fermentation techno...Fermented foods represent an important segment of current food markets,especially traditional or ethnic food markets.The demand for efficient utilization of agrowastes,together with advancements in fermentation technologies(microbial-and enzyme-based processing),are stimulating rapid growth and innovation in the fermented food sector.In addition,the health-promoting benefits of fermented foods are attracting increasingly attention.The microorganisms contained in many common fermented foods can serve as“microfactories”to generate nutrients and bioactives with specific nutritional and health functionalities.Herein,recent research relating to the manufacture of fermented foods are critically reviewed,placing emphasis on the potential health benefits of fermentation-enabled wellness foods.The importance of the correct selection of microorganisms and raw materials and the need for precise control of fermentation processes are explored.Major knowledge gaps and obstacles to fermented food production and market penetration are discussed.The importance of integrating multidisciplinary knowledge,communicating with consumers,establishing regulatory frameworks specifically for fermentation-enabled wellness foods and functional fermented foods,are highlighted.展开更多
The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐co...The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.展开更多
This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encaps...This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.展开更多
This novel study identifi es the effective anti-inflammatory phenolic compounds in dandelion and provides mechanistic insights into their interactions with receptor proteins(toll-like receptor 4,TLR4;co-receptor myelo...This novel study identifi es the effective anti-inflammatory phenolic compounds in dandelion and provides mechanistic insights into their interactions with receptor proteins(toll-like receptor 4,TLR4;co-receptor myeloid differentiation protein-2,MD-2)using UHPLC-ESI-MS/MS,lipopolysaccharide(LPS)-stimulated THP-1 cell line,fluorescence quenching and anisotropy,molecular docking(single ligand and multi-ligand docking)and molecular dynamics simulation.A 50%aqueous methanol extract had a greater anti-inflammatory effect and higher chicoric acid content,compared with the 100%water and 100%methanol extracts.Chicoric acid,chlorogenic acid,methylophiopogonone A,caffeic acid,gallic acid monohydrate and 4’-O-demethylbroussonin A had relatively high binding energies and contents in all extracts.Chicoric acid competed with chlorogenic acid,4’-O-demethylbroussonin A and quercetin for MD-2.Among dandelion’s phenolics,chicoric acid most effectively hindered TLR4-MD-2 complex formation,with a quenching constant of 0.62×10^(6) L/mol for MD-2 or TLR4 at 320 K,and binding energies of-6.87 and-5.97 kcal/mol,respectively,for MD-2 and TLR4.展开更多
The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, blac...The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots(BPQDs) were successfully dispersed on a graphitic carbon nitride(g-C3N4) support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO(6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%) compared with pure g-C3N4(2.65 μmol g^-1h^-1). This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.展开更多
The recovery of palladium from waste streams is of importance for metal recycling and environmental remediation.Herein,we present a“single-ion trap”strategy for efficiently recovering Pd(II)from superacidic solution...The recovery of palladium from waste streams is of importance for metal recycling and environmental remediation.Herein,we present a“single-ion trap”strategy for efficiently recovering Pd(II)from superacidic solutions and laboratory wastes.This was realized by rational design and synthesis of an antiparallel stacked covalent organic framework(ACOF)with hydrazine-carbonyl sites and pyridine sites for cooperative Pd(II)capture.The single-ion traps provided Lewis base sites with a high Pd(II)binding affinity,enabling the trapping of Pd(II)ions under a wide range of conditions.The developed ACOF-1 adsorbent demonstrated fast kinetics,excellent selectivity,and a high adsorption capacity of 412.9±14.2 mg/g for Pd(II)in a 3M HNO_(3) solution.When applied in a packed column,ACOF-1 dynamically captured Pd(II)from3M HNO_(3) solutions or laboratorywastes containing trace amounts of palladium and many other metals,realizing extraction efficiencies of 232.9 and 320.9 mg/g,respectively.Detailed experimental and theoretical studies revealed that the single-ion traps offered exceptionally strong binding of Pd(II)under both acidic and high ionic strength conditions,enabling selective adsorptive behavior not accessible using traditional adsorbents.Importantly,the general design strategy reported here could be used to create porous adsorbents for the capture of other precious metals.展开更多
Red-emissive carbon dots(R-CDs)have been widely studied because of their potential application in tissue imaging and optoelectronic devices.At present,most R-CDs are synthesized by using aromatic precursors,but the sy...Red-emissive carbon dots(R-CDs)have been widely studied because of their potential application in tissue imaging and optoelectronic devices.At present,most R-CDs are synthesized by using aromatic precursors,but the synthesis of R-CDs from non-aromatic precursors is challenging,and the emission mechanism remains unclear.Herein,different R-CDs were rationally synthesized using citric acid(CA),a prototype non-aromatic precursor,with the assistance of ammonia.Their structural evolution and optical mechanism were investigated.The addition of NH_(3)·H_(2)O played a key role in the synthesis of CA-based R-CDs,which shifted the emission wavelength of CA-based CDs from 423 to 667 nm.Mass spectrometry(MS)analysis indicated that the amino groups served as N dopants and promoted the formation of localized conjugated domains through an intermolecular amide ring,thereby inducing a significant emission redshift.The red-emissive mechanism of CDs was further confirmed by control experiments using other CA-like molecules(e.g.,aconitic acid,tartaric acid,aspartic acid,malic acid,and maleic acid)as precursors.MS,nuclear magnetic resonance characterization,and computational modeling revealed that the main carbon chain length of CA-like precursors tailored the cyclization mode,leading to hexatomic,pentatomic,unstable three/four-membered ring systems or cyclization failure.Among these systems,the hexatomic ring led to the largest emission redshift(244 nm,known for CA-based CDs).This work determined the origin of red emission in CA-based CDs,which would guide research on the controlled synthesis of R-CDs from other non-aromatic precursors.展开更多
Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispe...Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispersion of active metals at high metal loadings remains challenging,limiting the performance of SACs in many practical applications.Herein,we provide a comprehensive review of recent methods developed for synthesizing high-loading SACs,critically exploring their advantages,limitations,and wider applicability.Additionally,we showcase the benefits of high-loading SACs in the oxygen reduction reaction(ORR),water electrolysis,photocatalytic hydrogen production and CO oxidation.Although great recent progress has been made in the synthesis of high loading SACs,simple and universal routes that allowed the preprogrammed preparation of single metal and multi-metal SACs with specific metal coordination need to be discovered.展开更多
Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the pe...Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the performance of a homologous series of Zn-based layered double hydroxide(ZnM-LDH)photocatalysts for CO2 reduction.By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts(M=Ti4+,Fe3+,Co3+,Ga3+,Al3+),the product selectivity of the reaction could be precisely controlled.ZnTi-LDH afforded CH4 as the main reduction product;ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting;whilst ZnGa-LDH and ZnAl-LDH generated CO.In-situ diffuse reflectance infrared measurements,valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts.The analyses revealed that the d-band center(ed)position of the M3+or M4+cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2.Cations with d-band centers relatively close to the Fermi level(Ti4+,Ga3+and Al3+)adsorbed CO2 strongly yielding CH4 or CO,whereas metal cations with d-band centers further from the Fermi level(Fe3+and Co3+)adsorbed CO2 poorly,thereby yielding H2 only(from water splitting).Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction,paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.展开更多
The pyrolysis of zeolitic imidazolate frameworks(ZIFs) is becoming a popular approach for the synthesis of catalysts comprising porphyrin-like metal single atom catalysts(SACs) on N-doped carbons(M-N-C).Understanding ...The pyrolysis of zeolitic imidazolate frameworks(ZIFs) is becoming a popular approach for the synthesis of catalysts comprising porphyrin-like metal single atom catalysts(SACs) on N-doped carbons(M-N-C).Understanding the structural evolution of M-N-C as a function of ZIF pyrolysis temperature is important for realizing high performance catalysts.Herein,we report a detailed investigation of the evolution of Zn single atom catalyst sites during the pyrolysis of ZIF-8 at temperatures ranging from 500 to 900℃.Results from Zn L-edge and Zn K-edge X-ray absorption spectroscopy studies reveal that tetrahedral ZnN4 centers in ZIF-8 transform to porphyrin-like ZnN4 centers supported on N-doped carbon at temperatures as low as 600℃.As the pyrolysis temperature increased in the range 600-900℃,the Zn atoms moved closer to the N4 coordination plane.This subtle geometry change in the ZnN4 sites alters the electron density on the Zn atoms(formally Zn2+),strongly impacting the catalytic performance for the peroxidase-like decomposition of H2 O2.The catalyst obtained at 800℃(Zn-N-C-800) offered the best performance for H2 O2 decomposition.This work provides valuable new insights about the evolution of porphyrin-like single metal sites on N-doped carbons from ZIF precursors and the factors influencing SAC activity.展开更多
Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based ...Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based COF(PS-COF-1)with a Brunauer-Emmett-Teller(BET)surface area of 2703 m^(2) g^(-1),state-ofthe-art for an ionic COF.Aided by its ordered pore structure,chemical stability,and radiation resistance,PS-COF-1 showed exceptional adsorption properties toward aqueous ReO_(4)^(-)(1262 mg g^(-1))and ^(99)TcO_(4)^(-).Its adsorption performance surpassed its corresponding amorphous analogue.Importantly,PS-COF-1 exhibited fast adsorption kinetics,high adsorption capacities,and selectivity for ^(99)TcO_(4)^(-)and ReO_(4)^(-)at high ionic strengths,leading to the successful removal of ^(99)TcO_(4)^(-)under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites.In addition,PS-COF-1 can rapidly decontaminate ReO_(4)^(-)/^(99)TcO_(4)^(-)polluted potable water(~10 ppb)to drinking water level(0 ppb,part per billion)within 10 min.Density functional theory(DFT)calculations revealed PS-COF-1 has a strong affinity for ReO_(4)^(-)and ^(99)TcO_(4)^(-),thereby favoring adsorption of these low charge density anions over other common anions(e.g.,Cl^(-),NO_(3)^(-),SO_(4)^(2-),CO_(3)^(2-)).Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management.展开更多
Multicolor phosphors that respond rapidly to external stimuli are highly desirable for many applications, including lighting,optical displays and sensors. Herein, spiropyran(SP)-functionalized carbon dots(CDs) were sy...Multicolor phosphors that respond rapidly to external stimuli are highly desirable for many applications, including lighting,optical displays and sensors. Herein, spiropyran(SP)-functionalized carbon dots(CDs) were synthesized with a broad-spectrum output that were responsive to both ultraviolet(UV)/visible light and pH. The SP-CDs possessed strong ester linkages between the UV-absorbing/blue-emitting CDs and blue-absorbing/red-emitting surface SP groups, allowing efficient F?rster resonance energy transfer(FRET) between the donor and acceptor. UV irradiation or acid addition cause the SP ring opening to merocyanine(MC) or protonated MCH+forms, respectively, together with the formation of sheet-like aggregates. These processes enhanced the red emissions by the SP groups and attenuated blue emissions from the CDs. These changes were fully reversible under visible light or basic conditions, respectively, allowing dynamic regulation of the fluorescence properties(emission colors from blue to red, photoluminescence(PL) intensity) under photoirradiation on the timescale of minutes. As proof-of concept, we demonstrate that the emission properties of the SP-CDs can be used to construct UV and pH sensing materials as well as light emitting diode(LED) with different colors.展开更多
Fe-N-C electrocatalysts,comprising FeN_(4) single atom sites immobilized on N-doped carbon supports,offer excellent activity in the oxygen reduction reaction(ORR),especially in alkaline solution.Herein,we report a sim...Fe-N-C electrocatalysts,comprising FeN_(4) single atom sites immobilized on N-doped carbon supports,offer excellent activity in the oxygen reduction reaction(ORR),especially in alkaline solution.Herein,we report a simple synthetic strategy for improving the accessibility of FeN_(4) sites during ORR and simultaneously fine-tuning the microenvironment of FeN_(4) sites,thus enhancing the ORR activity.Our approach involved a simple one-step pyrolysis of a Fe-containing zeolitic imidazolate framework in the presence of NaCl,yielding a hierarchically porous Fe-N-C electrocatalyst containing tailored FeN_(4) sites with slightly elongated Fe-N bond distances and reduced Fe charge.The porous carbon structure improved mass transport during ORR,whilst the microenvironment optimized FeN_(4) sites benefitted the adsorption/desorption of ORR intermediates.Accordingly,the developed electrocatalyst,possessing a high FeN_(4) site density(9.9×10^(19) sites g^(-1))and turnover frequency(2.26 s^(-1)),delivered remarkable ORR performance with a low overpotential(a half-wave potential of 0.90 V vs.reversible hydrogen electrode)in 0.1 mol L^(-1) KOH.展开更多
The large-scale synthesis of platinum-free electrocatalysts for the oxygen reduction reaction(ORR)remains a grand challenge.We report the large-scale production of stable and active ORR electrocatalysts based on iron,...The large-scale synthesis of platinum-free electrocatalysts for the oxygen reduction reaction(ORR)remains a grand challenge.We report the large-scale production of stable and active ORR electrocatalysts based on iron,an earth-abundant element.A core–shell zeolitic imidazolate framework–tannic acid coordination polymer composite(ZIF-8@K-TA)was utilized as the catalyst precursor,which was transformed into iron atoms dispersed in hollow porous nitrogen-doped carbon capsules(H-Fe-N_(x)-C)through ion exchange and pyrolysis.H-Fe-N_(x)-C fea-tures site-isolated single-atom iron centers coordinated to nitrogen in graphitic layers,high levels of nitrogen doping,and high permeability to incoming gases.Benefiting from these characteristics,H-Fe-N_(x)-C demonstrated efficient electrocatalytic activity(E_(1/2)=0.92 V,vs.RHE)and stability towards the ORR in both alkaline and acidic media.In ORR performance,it surpassed the majority of recently reported Fe-N-C catalysts and the standard Pt/C catalyst.In addition,H-Fe-N_(x)-C showed outstanding tolerance to methanol.展开更多
Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a mi...Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a microwave-assisted strategy for the prepara-tion of SFM-CDs with blue,yellow and red emissions within 5 min from the same precursors.The as-prepared B-CDs,Y-CDs,and R-CDs possessed bright fluorescence at 425 nm,550 nm,and 640 nm,and photoluminescence quantum yields(PLQYs)of 54.68%,17.93%,and 2.88%,respectively.The structure of SFM-CDs consisted of 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid(TPCA)immobilized on the surface of a carbon core,with the size of the carbon core and degree of disulfide crosslinking between CDs both increasing on going from the B-CDs to the R-CDs,as verified by mechanochromic experiments.The excellent solid-state fluorescence performance of the SFM-CDs allowed their utilization as the fluorescent converter layer in multi-color LEDs and white LEDs with a high color rendering index.展开更多
The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extractio...The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extraction of uranium from seawater via converging the cooperative functions of adsorption-photocatalysis into the nanospace of covalent organic frameworks(COFs).Functionalization of the organic linkers in the multicomponent COFs allowed exploration of the relationship between material composition and adsorption-photocatalytic activity for uranium extraction.The presence of amidoxime groups in the COFs offered selective binding sites for uranyl,whilst triazine units and bipyridine-Pd groups acted cooperatively to photocatalytically reduce adsorbed U(Ⅵ)to a U(Ⅳ)solid product(UO2)for facile collection.One of our developed COFs,4-Pd-AO,displayed exceptional performance in sequestering and reducing uranyl from natural seawater,with a high extraction capacity of 4.62 mg U/g per day(average data)under visible light irradiation.Mechanistic studies revealed that 4-Pd-AO not only reduced adsorbed uranyl(Ⅵ)to U(Ⅳ)O_(2),but also generated ^(1)O_(2) and superoxide radicals under visible light excitation,thus affording excellent antibacterial and antialgal activities(i.e.,antibiofouling properties)for sustained efficient uranium extraction performance.This proof-ofconcept study establishes multicomponent COFs as promising candidates for efficient uranium extraction from seawater.展开更多
Pleurotus spp.was one of the most precious and common edible fungi,polysaccharides were the main active component.The structural,biological activities and structure-activity relationship(SAR)of polysaccharides from Pl...Pleurotus spp.was one of the most precious and common edible fungi,polysaccharides were the main active component.The structural,biological activities and structure-activity relationship(SAR)of polysaccharides from Pleurotus spp.were systematically reviewed.On the basis of structure and biological activity,structure-activity relationships were also analyzed and discussed to look forward to its future research direction and application prospect.In the past 5 years,about 30 kinds of polysaccharides were isolated from Pleurotus spp.,and their preliminary structures were studied,but the fine structures seldomly reported.The polysaccharides showed the activities of immunomodulatory,hypoglycemic,anti-inflammatory,antioxidant,anti-ageing,hepatoprotective,anti-tumor,hypolipidemic and regulating intestinal flora,but the mechanism was needed further study.There were few studies on the SAR of polysaccharides from Pleurotus,and the polysaccharides of P.eryngii were studied.It was found that the biological activities of polysaccharides were affected by molecular weight,monosaccharide composition,sugar chain structure and configuration.In addition,sulfonation and selenization could significantly increase the bioactivities of polysaccharides.These findings might help to better understand the research status of polysaccharides from Pleurotus spp.and provided a scientific basis for their application as functional foods.展开更多
Carbon dots(CDs)possess outstanding luminescence properties,making them widely used in optical displays,anti-counterfeiting systems,bioimaging,and sensors.Presently,there is much debate about the classification of CDs...Carbon dots(CDs)possess outstanding luminescence properties,making them widely used in optical displays,anti-counterfeiting systems,bioimaging,and sensors.Presently,there is much debate about the classification of CDs,as well as their formation process,structure,and fluorescence mechanisms.Aggregation plays an important role in the formation and fluorescence(e.g.,aggregationinduced emission)of CDs,yet is seldom studied in detail.This review aims fill this knowledge gap,by first exploring how aggregation leads to the formation of different types of CDs(e.g.,graphene quantum dots,carbon quantum dots,and carbonized polymer dots),followed by a detailed examination of the effect of aggregation-induced morphology on the luminescence properties and application of CDs.Finally,opportunities and challenges for the application of CDs in various applications are discussed,with the need for better mechanistic understanding of aggregation-induced luminescence being an imperative.展开更多
基金financially supported by the National Natural Science Foundation of China(31972149)funding support from the MacDiarmid Institute for Advanced Materials and Nanotechnologythe Dodd-Walls Centre for Photonic and Quantum Technologies。
文摘Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-satellite SERS aptasensor was constructed by combining aptamer-decorated Fe_(3)O_(4)@Au MNPs(as the recognize probe for histamine)and complementary DNA-modified silver nanoparticles carrying 4-mercaptobenzonitrile(4-MBN)(Ag@4-MBN@Ag-c-DNA)as the SERS signal probe for the indirect detection of histamine.Under an applied magnetic field in the absence of histamine,the assembly gave an intense Raman signal at“Raman biological-silent”region due to 4-MBN.In the presence of histamine,the Ag@4-MBN@Ag-c-DNA SERS-tag was released from the Fe_(3)O_(4)@Au MNPs,thus decreasing the SERS signal.Under optimal conditions,an ultra-low limit of detection of 0.65×10^(-3)ng/mL and a linear range 10^(-2)-10^5 ng/mL on the SERS aptasensor were obtained.The histamine content in four food samples were analyzed using the SERS aptasensor,with the results consistent with those determined by high performance liquid chromatography.The present work highlights the merits of indirect strategies for the ultrasensitive and highly selective SERS detection of small biological molecules in complex matrices.
基金financial support from the National Key R&D Program of China (Grant Nos.: 2017YFA0206904, 2017YFA0206900, and 2016YFB0600901)the National Program on Key Basic Research Project (Grant No.: 2014CB239402)+6 种基金the National Natural Science Foundation of China (Grant Nos.: 51772305, 51572270, U1662118, 31671489, U1332205, and 21701131)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.: XDB17000000)the Royal Society Newton Advanced Fellowship (Grant No.: NA170422)the Young Elite Scientist Sponsorship Program by CAST (Grant No.: YESS20160137)the Youth Innovation Promotion Association of the CASthe Fund of Xi’an University of Science and Technology (Grant No.:2018QDJ014)funding support from the Energy Education Trust of New Zealand
文摘For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas.To date,the synthesis of catalysts that are both ultrathin(monolayer)and ultrafine(lateral size<10nm)has proven extremely challenging.Herein,using a facile ultrasonic exfoliation procedure,we describe the successful synthesis of ultrafine ZnCo-LDH nanosheets(denoted as ZnCo-UF)with a size^3.5 nm and thickness^0.5 nm.The single layer ZnCo-UF nanosheets possess an abundance of oxygen vacancies(Vo)and unsaturated coordination s让es,thereby affording outstanding electrocatalytic water oxidation performance.DFT calculations confirmed that Vo on the surface of ZnCo-UF enhanced H20 adsorption via increasing the electropositivity of the nanosheets.
文摘Fermented foods represent an important segment of current food markets,especially traditional or ethnic food markets.The demand for efficient utilization of agrowastes,together with advancements in fermentation technologies(microbial-and enzyme-based processing),are stimulating rapid growth and innovation in the fermented food sector.In addition,the health-promoting benefits of fermented foods are attracting increasingly attention.The microorganisms contained in many common fermented foods can serve as“microfactories”to generate nutrients and bioactives with specific nutritional and health functionalities.Herein,recent research relating to the manufacture of fermented foods are critically reviewed,placing emphasis on the potential health benefits of fermentation-enabled wellness foods.The importance of the correct selection of microorganisms and raw materials and the need for precise control of fermentation processes are explored.Major knowledge gaps and obstacles to fermented food production and market penetration are discussed.The importance of integrating multidisciplinary knowledge,communicating with consumers,establishing regulatory frameworks specifically for fermentation-enabled wellness foods and functional fermented foods,are highlighted.
文摘The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.
基金supported by the Shandong Provincial Natural Science Foundation of China(ZR2019BC100)Science,Education and Industry Integration Innovation Pilot Project of Qilu University of Technology(Shandong Academy of Sciences)(2020KJC-ZD10)Incubation Program of Youth Innovation in Shandong Province。
文摘This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.
基金supported by the funding“Innovation Project of Shandong Province Agricultural Application Technology”(2130106)“Key Technology Research and Development Program of Shandong”(2019GNC106004).
文摘This novel study identifi es the effective anti-inflammatory phenolic compounds in dandelion and provides mechanistic insights into their interactions with receptor proteins(toll-like receptor 4,TLR4;co-receptor myeloid differentiation protein-2,MD-2)using UHPLC-ESI-MS/MS,lipopolysaccharide(LPS)-stimulated THP-1 cell line,fluorescence quenching and anisotropy,molecular docking(single ligand and multi-ligand docking)and molecular dynamics simulation.A 50%aqueous methanol extract had a greater anti-inflammatory effect and higher chicoric acid content,compared with the 100%water and 100%methanol extracts.Chicoric acid,chlorogenic acid,methylophiopogonone A,caffeic acid,gallic acid monohydrate and 4’-O-demethylbroussonin A had relatively high binding energies and contents in all extracts.Chicoric acid competed with chlorogenic acid,4’-O-demethylbroussonin A and quercetin for MD-2.Among dandelion’s phenolics,chicoric acid most effectively hindered TLR4-MD-2 complex formation,with a quenching constant of 0.62×10^(6) L/mol for MD-2 or TLR4 at 320 K,and binding energies of-6.87 and-5.97 kcal/mol,respectively,for MD-2 and TLR4.
基金supported by the National Natural Science Foundation of China (51502146, U1404506, 21671113, 51772305, 51572270, and U1662118)the International Partnership Program of Chinese Academy of Sciences (GJHZ1819)+1 种基金the Royal Society-Newton Advanced Fellowship (NA170422)supported by Open Fund (PEBM201702) of Key Laboratory for Photonic and Electric Bandgap Materials, Ministry of Education (Harbin Normal University)
文摘The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots(BPQDs) were successfully dispersed on a graphitic carbon nitride(g-C3N4) support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO(6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%) compared with pure g-C3N4(2.65 μmol g^-1h^-1). This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.
基金supported by the National Natural Science Foundation of China(NSFC,grant nos.U2167218,22322603,and 22276054)the Beijing Outstanding Young Scientist Program,the Robert A.Welch Foundation(grant no.B-0027)the New Zealand James Cook Research Fellowship.
文摘The recovery of palladium from waste streams is of importance for metal recycling and environmental remediation.Herein,we present a“single-ion trap”strategy for efficiently recovering Pd(II)from superacidic solutions and laboratory wastes.This was realized by rational design and synthesis of an antiparallel stacked covalent organic framework(ACOF)with hydrazine-carbonyl sites and pyridine sites for cooperative Pd(II)capture.The single-ion traps provided Lewis base sites with a high Pd(II)binding affinity,enabling the trapping of Pd(II)ions under a wide range of conditions.The developed ACOF-1 adsorbent demonstrated fast kinetics,excellent selectivity,and a high adsorption capacity of 412.9±14.2 mg/g for Pd(II)in a 3M HNO_(3) solution.When applied in a packed column,ACOF-1 dynamically captured Pd(II)from3M HNO_(3) solutions or laboratorywastes containing trace amounts of palladium and many other metals,realizing extraction efficiencies of 232.9 and 320.9 mg/g,respectively.Detailed experimental and theoretical studies revealed that the single-ion traps offered exceptionally strong binding of Pd(II)under both acidic and high ionic strength conditions,enabling selective adsorptive behavior not accessible using traditional adsorbents.Importantly,the general design strategy reported here could be used to create porous adsorbents for the capture of other precious metals.
基金supported by the National Natural Science Foundation of China(52122308,21905253,51973200,and 52103239)Natural Science Foundation of Henan Province(202300410372)Henan Postdoctoral Foundation。
文摘Red-emissive carbon dots(R-CDs)have been widely studied because of their potential application in tissue imaging and optoelectronic devices.At present,most R-CDs are synthesized by using aromatic precursors,but the synthesis of R-CDs from non-aromatic precursors is challenging,and the emission mechanism remains unclear.Herein,different R-CDs were rationally synthesized using citric acid(CA),a prototype non-aromatic precursor,with the assistance of ammonia.Their structural evolution and optical mechanism were investigated.The addition of NH_(3)·H_(2)O played a key role in the synthesis of CA-based R-CDs,which shifted the emission wavelength of CA-based CDs from 423 to 667 nm.Mass spectrometry(MS)analysis indicated that the amino groups served as N dopants and promoted the formation of localized conjugated domains through an intermolecular amide ring,thereby inducing a significant emission redshift.The red-emissive mechanism of CDs was further confirmed by control experiments using other CA-like molecules(e.g.,aconitic acid,tartaric acid,aspartic acid,malic acid,and maleic acid)as precursors.MS,nuclear magnetic resonance characterization,and computational modeling revealed that the main carbon chain length of CA-like precursors tailored the cyclization mode,leading to hexatomic,pentatomic,unstable three/four-membered ring systems or cyclization failure.Among these systems,the hexatomic ring led to the largest emission redshift(244 nm,known for CA-based CDs).This work determined the origin of red emission in CA-based CDs,which would guide research on the controlled synthesis of R-CDs from other non-aromatic precursors.
基金The work was supported by the National Natural Science Foundation of China(No.92061125,22209186)Beijing Natural Science Foundation(No.Z200012)+1 种基金Jiangxi Natural Science Foundation(No.20212ACB213009,20223BBG74004)Youth Innovation Promotion Association,CAS(No.2023343)。
文摘Single-atom catalysts(SACs)attract significant attention owing to their high catalytic activity,high metal atom utilization efficiency,and well-defined and configurable active sites.However,achieving single-atom dispersion of active metals at high metal loadings remains challenging,limiting the performance of SACs in many practical applications.Herein,we provide a comprehensive review of recent methods developed for synthesizing high-loading SACs,critically exploring their advantages,limitations,and wider applicability.Additionally,we showcase the benefits of high-loading SACs in the oxygen reduction reaction(ORR),water electrolysis,photocatalytic hydrogen production and CO oxidation.Although great recent progress has been made in the synthesis of high loading SACs,simple and universal routes that allowed the preprogrammed preparation of single metal and multi-metal SACs with specific metal coordination need to be discovered.
基金financial support from the National Key Projects for Fundamental Research and Development of China (2016YFB0600901, 2017YFA0206904, 2017YFA0206900, 2018YFB1502002)the National Natural Science Foundation of China (51825205, 51772305, 51572270, U1662118, 21871279, 21802154, 21902168)+10 种基金the Beijing Natural Science Foundation (2191002, 2182078, 2194089)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17000000)the Royal Society-Newton Advanced Fellowship (NA170422)the International Partnership Program of Chinese Academy of Sciences (GJHZ1819, GJHZ201974)the Beijing Municipal Science and Technology Project (Z181100005118007)the K. C. Wong Education Foundationthe Young Elite Scientist Sponsorship Program by CAST (YESS)the Youth Innovation Promotion Association of the CASthe Energy Education Trust of New Zealandthe Mac Diarmid Institute for Advanced Materials and Nanotechnologythe Dodd Walls Centre for Photonic and Quantum Technologies。
文摘Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals.However,factors controlling product selectivity remain poorly understood.Herein,we compared the performance of a homologous series of Zn-based layered double hydroxide(ZnM-LDH)photocatalysts for CO2 reduction.By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts(M=Ti4+,Fe3+,Co3+,Ga3+,Al3+),the product selectivity of the reaction could be precisely controlled.ZnTi-LDH afforded CH4 as the main reduction product;ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting;whilst ZnGa-LDH and ZnAl-LDH generated CO.In-situ diffuse reflectance infrared measurements,valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts.The analyses revealed that the d-band center(ed)position of the M3+or M4+cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2.Cations with d-band centers relatively close to the Fermi level(Ti4+,Ga3+and Al3+)adsorbed CO2 strongly yielding CH4 or CO,whereas metal cations with d-band centers further from the Fermi level(Fe3+and Co3+)adsorbed CO2 poorly,thereby yielding H2 only(from water splitting).Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction,paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.
基金supported by the Ministry of Business, Innovation and Employment Catalyst Fund (MAUX 1609)the University of Auckland Faculty Research Development Fund+1 种基金the MacDiarmid Institute for Advanced Materials and Nanotechnologya generous philanthropic donation from Greg and Kathryn Trounson。
文摘The pyrolysis of zeolitic imidazolate frameworks(ZIFs) is becoming a popular approach for the synthesis of catalysts comprising porphyrin-like metal single atom catalysts(SACs) on N-doped carbons(M-N-C).Understanding the structural evolution of M-N-C as a function of ZIF pyrolysis temperature is important for realizing high performance catalysts.Herein,we report a detailed investigation of the evolution of Zn single atom catalyst sites during the pyrolysis of ZIF-8 at temperatures ranging from 500 to 900℃.Results from Zn L-edge and Zn K-edge X-ray absorption spectroscopy studies reveal that tetrahedral ZnN4 centers in ZIF-8 transform to porphyrin-like ZnN4 centers supported on N-doped carbon at temperatures as low as 600℃.As the pyrolysis temperature increased in the range 600-900℃,the Zn atoms moved closer to the N4 coordination plane.This subtle geometry change in the ZnN4 sites alters the electron density on the Zn atoms(formally Zn2+),strongly impacting the catalytic performance for the peroxidase-like decomposition of H2 O2.The catalyst obtained at 800℃(Zn-N-C-800) offered the best performance for H2 O2 decomposition.This work provides valuable new insights about the evolution of porphyrin-like single metal sites on N-doped carbons from ZIF precursors and the factors influencing SAC activity.
基金supported by the National Natural Science Foundation of China(U2167218 and 22006036)the National Key Research and Development Program of China(2017YFA0207002 and 2018YFC1900105)+2 种基金the Science Challenge Project(TZ2016004)the Beijing Outstanding Young Scientist Program(H.Y.and X.W.)the Robert A.Welch Foundation(B-0027)(S.M.)。
文摘Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based COF(PS-COF-1)with a Brunauer-Emmett-Teller(BET)surface area of 2703 m^(2) g^(-1),state-ofthe-art for an ionic COF.Aided by its ordered pore structure,chemical stability,and radiation resistance,PS-COF-1 showed exceptional adsorption properties toward aqueous ReO_(4)^(-)(1262 mg g^(-1))and ^(99)TcO_(4)^(-).Its adsorption performance surpassed its corresponding amorphous analogue.Importantly,PS-COF-1 exhibited fast adsorption kinetics,high adsorption capacities,and selectivity for ^(99)TcO_(4)^(-)and ReO_(4)^(-)at high ionic strengths,leading to the successful removal of ^(99)TcO_(4)^(-)under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites.In addition,PS-COF-1 can rapidly decontaminate ReO_(4)^(-)/^(99)TcO_(4)^(-)polluted potable water(~10 ppb)to drinking water level(0 ppb,part per billion)within 10 min.Density functional theory(DFT)calculations revealed PS-COF-1 has a strong affinity for ReO_(4)^(-)and ^(99)TcO_(4)^(-),thereby favoring adsorption of these low charge density anions over other common anions(e.g.,Cl^(-),NO_(3)^(-),SO_(4)^(2-),CO_(3)^(2-)).Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management.
基金supported by the National Natural Science Foundation of China(52122308,21905253,51973200,52103239)the Natural Science Foundation of Henan(202300410372)+2 种基金Henan Postdoctoral Foundationfunding support from the MacDiarmid Institute for Advanced MaterialsNanotechnology and the Dodd-Walls Centre for Photonic and Quantum Technologies。
文摘Multicolor phosphors that respond rapidly to external stimuli are highly desirable for many applications, including lighting,optical displays and sensors. Herein, spiropyran(SP)-functionalized carbon dots(CDs) were synthesized with a broad-spectrum output that were responsive to both ultraviolet(UV)/visible light and pH. The SP-CDs possessed strong ester linkages between the UV-absorbing/blue-emitting CDs and blue-absorbing/red-emitting surface SP groups, allowing efficient F?rster resonance energy transfer(FRET) between the donor and acceptor. UV irradiation or acid addition cause the SP ring opening to merocyanine(MC) or protonated MCH+forms, respectively, together with the formation of sheet-like aggregates. These processes enhanced the red emissions by the SP groups and attenuated blue emissions from the CDs. These changes were fully reversible under visible light or basic conditions, respectively, allowing dynamic regulation of the fluorescence properties(emission colors from blue to red, photoluminescence(PL) intensity) under photoirradiation on the timescale of minutes. As proof-of concept, we demonstrate that the emission properties of the SP-CDs can be used to construct UV and pH sensing materials as well as light emitting diode(LED) with different colors.
基金supported by a James Cook Research Fellowship,administered by the Royal Society Te Apārangifunding support from Greg and Kathryn Trounson,the Energy Education Trust of New Zealand,the Mac Diarmid Institute for Advanced Materials and Nanotechnology,the National Key Projects for Fundamental Research and Development of China(2017YFA0206904 and 2017YFA0206900)+1 种基金the National Natural Science Foundation of China(51825205 and 21871279)the Beijing Natural Science Foundation(2191002)。
文摘Fe-N-C electrocatalysts,comprising FeN_(4) single atom sites immobilized on N-doped carbon supports,offer excellent activity in the oxygen reduction reaction(ORR),especially in alkaline solution.Herein,we report a simple synthetic strategy for improving the accessibility of FeN_(4) sites during ORR and simultaneously fine-tuning the microenvironment of FeN_(4) sites,thus enhancing the ORR activity.Our approach involved a simple one-step pyrolysis of a Fe-containing zeolitic imidazolate framework in the presence of NaCl,yielding a hierarchically porous Fe-N-C electrocatalyst containing tailored FeN_(4) sites with slightly elongated Fe-N bond distances and reduced Fe charge.The porous carbon structure improved mass transport during ORR,whilst the microenvironment optimized FeN_(4) sites benefitted the adsorption/desorption of ORR intermediates.Accordingly,the developed electrocatalyst,possessing a high FeN_(4) site density(9.9×10^(19) sites g^(-1))and turnover frequency(2.26 s^(-1)),delivered remarkable ORR performance with a low overpotential(a half-wave potential of 0.90 V vs.reversible hydrogen electrode)in 0.1 mol L^(-1) KOH.
基金Foundation(B?0027)(SM),National Science Foundation of China(Grants 22006036)North China Electric Power University(XM2112307)(HY and XW)+1 种基金GINW is supported by a James Cook Research Fellowship from New Zealand Government funding,administered by the Royal Society Te Aparangisupport from the XAS beamline scientists of the Australian Synchrotron and the 14 W station of the Shanghai Synchrotron Radiation Facility(SSRF).
文摘The large-scale synthesis of platinum-free electrocatalysts for the oxygen reduction reaction(ORR)remains a grand challenge.We report the large-scale production of stable and active ORR electrocatalysts based on iron,an earth-abundant element.A core–shell zeolitic imidazolate framework–tannic acid coordination polymer composite(ZIF-8@K-TA)was utilized as the catalyst precursor,which was transformed into iron atoms dispersed in hollow porous nitrogen-doped carbon capsules(H-Fe-N_(x)-C)through ion exchange and pyrolysis.H-Fe-N_(x)-C fea-tures site-isolated single-atom iron centers coordinated to nitrogen in graphitic layers,high levels of nitrogen doping,and high permeability to incoming gases.Benefiting from these characteristics,H-Fe-N_(x)-C demonstrated efficient electrocatalytic activity(E_(1/2)=0.92 V,vs.RHE)and stability towards the ORR in both alkaline and acidic media.In ORR performance,it surpassed the majority of recently reported Fe-N-C catalysts and the standard Pt/C catalyst.In addition,H-Fe-N_(x)-C showed outstanding tolerance to methanol.
基金supported by the National Natural Science Foundation of China(52122308,21905253,51973200,52203244,21725304)the Natural Science Foundation of Henan Province(202300410372)the China Postdoctoral Science Foundation(2022M712868).
文摘Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a microwave-assisted strategy for the prepara-tion of SFM-CDs with blue,yellow and red emissions within 5 min from the same precursors.The as-prepared B-CDs,Y-CDs,and R-CDs possessed bright fluorescence at 425 nm,550 nm,and 640 nm,and photoluminescence quantum yields(PLQYs)of 54.68%,17.93%,and 2.88%,respectively.The structure of SFM-CDs consisted of 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid(TPCA)immobilized on the surface of a carbon core,with the size of the carbon core and degree of disulfide crosslinking between CDs both increasing on going from the B-CDs to the R-CDs,as verified by mechanochromic experiments.The excellent solid-state fluorescence performance of the SFM-CDs allowed their utilization as the fluorescent converter layer in multi-color LEDs and white LEDs with a high color rendering index.
基金funding support from the National Science Foundation of China(grant nos.U2167218 and 22006036)National Key Research and Development Program of China(grant nos.2017YFA0207002 and 2018YFC1900105)+4 种基金the Science Challenge Project(grant no.TZ2016004)the Beijing Outstanding Young Scientist Programthe Students Innovation Training Program(grant no.202106014)the Robert A.Welch Foundation(B-0027)(S.M.)support from the 14W station in Shanghai Synchrotron Radiation Facility(SSRF).
文摘The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extraction of uranium from seawater via converging the cooperative functions of adsorption-photocatalysis into the nanospace of covalent organic frameworks(COFs).Functionalization of the organic linkers in the multicomponent COFs allowed exploration of the relationship between material composition and adsorption-photocatalytic activity for uranium extraction.The presence of amidoxime groups in the COFs offered selective binding sites for uranyl,whilst triazine units and bipyridine-Pd groups acted cooperatively to photocatalytically reduce adsorbed U(Ⅵ)to a U(Ⅳ)solid product(UO2)for facile collection.One of our developed COFs,4-Pd-AO,displayed exceptional performance in sequestering and reducing uranyl from natural seawater,with a high extraction capacity of 4.62 mg U/g per day(average data)under visible light irradiation.Mechanistic studies revealed that 4-Pd-AO not only reduced adsorbed uranyl(Ⅵ)to U(Ⅳ)O_(2),but also generated ^(1)O_(2) and superoxide radicals under visible light excitation,thus affording excellent antibacterial and antialgal activities(i.e.,antibiofouling properties)for sustained efficient uranium extraction performance.This proof-ofconcept study establishes multicomponent COFs as promising candidates for efficient uranium extraction from seawater.
基金supported by National Key R&D Program of China(2018YFD0400200)Major Public Welfare Projects in Henan Province(201300110200)+1 种基金Research on Precision Nutrition and Health Food,Department of Science and Technology of Henan Province(CXJD2021006)The Key Project in Science and Technology Agency of Henan Province(202102110283 and 212102110019).
文摘Pleurotus spp.was one of the most precious and common edible fungi,polysaccharides were the main active component.The structural,biological activities and structure-activity relationship(SAR)of polysaccharides from Pleurotus spp.were systematically reviewed.On the basis of structure and biological activity,structure-activity relationships were also analyzed and discussed to look forward to its future research direction and application prospect.In the past 5 years,about 30 kinds of polysaccharides were isolated from Pleurotus spp.,and their preliminary structures were studied,but the fine structures seldomly reported.The polysaccharides showed the activities of immunomodulatory,hypoglycemic,anti-inflammatory,antioxidant,anti-ageing,hepatoprotective,anti-tumor,hypolipidemic and regulating intestinal flora,but the mechanism was needed further study.There were few studies on the SAR of polysaccharides from Pleurotus,and the polysaccharides of P.eryngii were studied.It was found that the biological activities of polysaccharides were affected by molecular weight,monosaccharide composition,sugar chain structure and configuration.In addition,sulfonation and selenization could significantly increase the bioactivities of polysaccharides.These findings might help to better understand the research status of polysaccharides from Pleurotus spp.and provided a scientific basis for their application as functional foods.
基金National Natural Science Foundation of China,Grant/Award Numbers:52122308,21905253,51973200,52103239Natural Science Foundation of Henan Province,Grant/Award Number:202300410372。
文摘Carbon dots(CDs)possess outstanding luminescence properties,making them widely used in optical displays,anti-counterfeiting systems,bioimaging,and sensors.Presently,there is much debate about the classification of CDs,as well as their formation process,structure,and fluorescence mechanisms.Aggregation plays an important role in the formation and fluorescence(e.g.,aggregationinduced emission)of CDs,yet is seldom studied in detail.This review aims fill this knowledge gap,by first exploring how aggregation leads to the formation of different types of CDs(e.g.,graphene quantum dots,carbon quantum dots,and carbonized polymer dots),followed by a detailed examination of the effect of aggregation-induced morphology on the luminescence properties and application of CDs.Finally,opportunities and challenges for the application of CDs in various applications are discussed,with the need for better mechanistic understanding of aggregation-induced luminescence being an imperative.