In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented...In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.展开更多
Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic p...Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.展开更多
For nano-collision, regulating the interaction between nanoparticles(NPs) and electrode interfaces is crucial for the precise analysis of individual NPs. However, existing ultramicroelectrodes(UMEs) suffer from narrow...For nano-collision, regulating the interaction between nanoparticles(NPs) and electrode interfaces is crucial for the precise analysis of individual NPs. However, existing ultramicroelectrodes(UMEs) suffer from narrow electrochemical window and poor electrode interface adhesion, severely hindering the application of precise single NP analysis. Here, we propose a simple and effective interface modification strategy. By electrochemically self-assembling poly(diallyldimethylammonium chloride)(PC) on the surface of carbon nanocone electrodes(CNCEs), we successfully prepared PC-modified CNCEs(PC–CNCEs). These electrodes not only possess sufficiently wide electrochemical window but also exhibit strong adhesion to negatively charged Ag NPs on their surfaces. Surface physical analysis and electrochemical molecule detection validated the high-density loading of PC on the modified electrodes. Furthermore, the working principle of PC–CNCEs for single Ag NP collision detection was further verified through the techniques of nanocollision and double-potential steps. Leveraging these significant advantages, PC–CNCEs not only achieved precise measurements of single or mixed-sized Ag NPs but also detected Ag NP solutions at concentrations as low as fmol/L levels. This advancement offers a new strategy for the rapid and precise analysis of NP colloids.展开更多
Shear banding in entangled polymer melts remains a fundamental yet unresolved phenomenon in nonlinear polymer rheology.Here,we perform molecular dynamics simulations of bidisperse entangled melts—comprising equal num...Shear banding in entangled polymer melts remains a fundamental yet unresolved phenomenon in nonlinear polymer rheology.Here,we perform molecular dynamics simulations of bidisperse entangled melts—comprising equal numbers of chains with lengths N=200 and N=400—to uncover the structural origins and dynamic evolution of shear banding.This bidisperse system amplifies spatial heterogeneities in the entanglement network and facilitates direct comparison with monodisperse melts of N=300,revealing quantitatively consistent steady-state shear stress versus shear rate responses.Notably,a pronounced stress plateau spanning over an order of magnitude in shear rate is observed,within which shear banding emerges reproducibly across independent simulations,as confirmed by systematic velocity profile and interface position analyses.Our findings challenge the prevailing notion that shear banding arises solely from dynamic flow instabilities.Instead,we establish a microstructure-driven framework,demonstrating that shear band nucleation is governed by pre-existing structural heterogeneities—specifically,localized weakening of the entanglement network at short-chain-enriched“soft spots”,indicative of a robust microstructural memory effect.During shear start-up,short chains preferentially disentangle and migrate along the shear direction;beyond a critical strain,long chains retract and redistribute away from the fast shear band center to minimize elastic energy.This chain-length-dependent migration dynamically enriches the shear band in short chains,stabilizing its structure and revealing a molecular mechanism that links entanglement heterogeneity to macroscopic flow localization.By bridging molecular-scale structural features with nonlinear rheological responses,this work offers a complementary perspective to classical tube and convective constraint release(CCR)models,highlighting the critical interplay between microstructural heterogeneity and chain migration in the onset and persistence of shear banding.展开更多
Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA...Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.展开更多
The crystallization behavior of two commercial polyolefin elastomer(POE)samples was investigated using the fast scanning chip calorimetry(FSC)technique.Non-isothermal crystallization of the POE samples during cooling ...The crystallization behavior of two commercial polyolefin elastomer(POE)samples was investigated using the fast scanning chip calorimetry(FSC)technique.Non-isothermal crystallization of the POE samples during cooling to low temperatures cannot be inhibited under the largest efficient cooling rate employed in the current work.Thus,the isothermal crystallization of POE samples was limited to a narrow temperature range.When the POE samples were cooled to a certain temperature below the non-isothermal crystallization temperature for crystallization,a crystallization time dependent melting peak appeared in the low temperature region besides the high temperature melting peak originated from the non-isothermal crystallization.This low temperature melting peak was arisen from the melting of crystals isothermally crystallized at the selected crystallization temperature.At each crystallization temperature,the lengths of crystallizable segments were different,thus,the low melting peak increased with increasing the crystallization temperature.In terms of the high melting peak attributed to the non-isothermally crystallized crystals,it somehow decreased with increasing crystallization time and then became constant with further increasing crystallization time at the selected crystallization temperature.This could be explained by the fact that the crystallizable sequences with longer length would nucleate and crystallize first to form thicker crystals during cooling.The subsequent crystallization contributed by the shorter crystallizable sequences will result in the formation of thinner crystals,causing the melting peak to shift to the lower temperature.展开更多
The development of robust and active oxygen evolution reaction(OER)electrocatalysts is urgently desirable for the widespread implementation of proton exchange membrane water electrolyzers(PEMWE),yet remains a critical...The development of robust and active oxygen evolution reaction(OER)electrocatalysts is urgently desirable for the widespread implementation of proton exchange membrane water electrolyzers(PEMWE),yet remains a critical challenge.We propose a catalyst named U-IrRuO_(x)@IrRu(where“U”denotes“ultrathin”),which features a spontaneously formed amorphous oxide shell that synergistically optimizes the electronic structure and corrosion resistance.Combined experimental and theoretical studies reveal that the oxyphilic Ru-induced electronic modulation weakens Ir-O binding strength,thereby accelerating the rate-determining step of ^(*)OOH formation.In addition,the metallic alloy core functions as an electron reservoir,suppressing excessive oxidation of active sites while ensuring high conductivity.Due to these attributes,the U-IrRuO_(x)@IrRu demonstrates a low overpotential of 230 mV at 10 mA cm^(-2),outperforming commercial IrO_(2)(CM)by 65 mV.When integrated into a PEMWE with an ultra-low Ir loading of 0.25 mg_(Ir)cm^(-2),it delivers an industrial current density of 2 A cm^(-2)at 1.74 V and 3 A cm^(-2)at 1.836 V,surpassing the U.S.Department of Energy(DOE)2025 target.More impressively,the U-IrRuOx@IrRubased electrolyzer can stably operate for over 550 h,with an extremely low decay rate of 7.52μV h^(-1),corresponding to a predicted lifespan of 23,000 h with 90%performance retention.展开更多
Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic r...Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.展开更多
Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we de...Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.展开更多
Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graph...Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graphite intercalation compounds (AGICs) have been coming into their own in dual-ion batteries [1]. It is imperative to deepen an understanding of anion storage mechanisms in graphite electrode.展开更多
Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C...Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.展开更多
The efficient enrichment and separation of rare earth elements(REEs) from sulfate leachates of ionadsorption type rare earth ore(IATREO) is still a challenge.This work presents a novel extractant 2-(bis((2-ethylhexyl)...The efficient enrichment and separation of rare earth elements(REEs) from sulfate leachates of ionadsorption type rare earth ore(IATREO) is still a challenge.This work presents a novel extractant 2-(bis((2-ethylhexyl)oxy)phosphoryl)-2-hydroxyacetic acid(HPOAc) for the selective extraction and efficie nt enrichment of REEs from sulfate leachates of IATREO.HPOAc exhibits higher extraction ability for all fifteen REEs(Ⅲ) than naphthenic acid(NA) at pH_(ini)=1,56.Furthermore,it has no drawbacks of di-(2-ethylhexyl) phosphoric acid(P204) and 2-ethylhexyl phosphoric acid mono-2-ethylhexylester(P507)such as weak extraction ability towards light REEs(Ⅲ) and high stripping acidity for heavy REEs(Ⅲ).It has better separation performance for metal ion impurities than P204 and P507,especially for the typical impurity Al(Ⅲ).Furthermore,the HPOAc system has better phase separation behavior and extraction pheno mena.A simulated operation with two-stage counte r-current extraction and single-stage stripping of REEs was carried out using unsaponified HPOAc.The recovery of REEs reaches 98.7%.The concentration of REEs increases from 0.44 to 130.35 g/L,indicating a nearly 300-fold increase.Furthermore,the content of REEs increases from 77.8 wt% to 97.6 wt%.So HPOAc has the potential to selectively recover REEs from sulfate leachates of IATREO.展开更多
The microstructural evolution of a thermoplastic polyurethane(TPU)with low hard segment content has been monitored utilizing in situ real-time synchrotron small angle X-ray scattering(SAXS)and time-domain nuclear magn...The microstructural evolution of a thermoplastic polyurethane(TPU)with low hard segment content has been monitored utilizing in situ real-time synchrotron small angle X-ray scattering(SAXS)and time-domain nuclear magnetic resonance(NMR)measurements.The TPU is composed of 23 wt% of[4,4-methylenediphenyl diisocyanate(MDI)]-[1,4-butanediol(BD)]chain segments,which form hard domains,as[polytetrahydrofuran(PTHF)]forming soft domains.The number and distribution of monomer units in hard blocks is determined by the successive self-nucleation and annealing thermal fractionation technique.In situ SAXS method reveals heating-induced increase in the spacing of hard and soft domains,while time-domain ^(1)H-NMR characterizes the changes in the phase composition and chain dynamics in these domains.A glassy fraction of short MDI-BD chain segments in hard domains passes through T_(g) above ambient temperature.At higher temperatures,MDI-BD nanocrystals start to melt.Sequence length distribution of MDI-BD chain segments causes a distribution in crystal sizes and wide melting temperature range.The melting is accompanied by the mixing of MDI-BD with PTHF segments in soft domains,and by increase in segmental mobility in these domains.Above 180℃,the TPU melt is homogeneous on the scale above nanometers according to SAXS data.展开更多
Polyethyleneimine(PEI),as a widely used polymer material in the field of gene delivery,has been extensively studied for modification and shielding to reduce its cytotoxicity.However,research aimed at preparing degrada...Polyethyleneimine(PEI),as a widely used polymer material in the field of gene delivery,has been extensively studied for modification and shielding to reduce its cytotoxicity.However,research aimed at preparing degradable PEI is scarce.In this work,the hydrogen peroxide(H_(2)O_(2))oxidation method was used to introduce degradable amide groups in the PEI and a series of oxidized PEI22k(oxPEI22k)with different degrees of oxidation were synthesized by regulating the dosage of H_(2)O_(2).The relationship between the oxidation degree of oxPEI22k and the gene transfection efficiency of oxPEI22k was studied in detail,confirming that the oxPEI22k with oxidation degrees of 16.7%and 28.6%achieved improved transfection efficiency compared to unmodified PEI.These oxPEI22k also proved reduced cytotoxicity and improved degradability.Further,this strategy was extended to the synthesis of low-molecular-weight oxPEI1.8k.The oxPEI1.8k with suitable oxidation degree also achieved improved transfection efficiency and reduced cytotoxicity.In brief,this work provided high-efficiency and low-cytotoxicity degradable gene delivery carriers by regulating the oxidation degree of PEI,which was of great significance for promoting clinical applications of PEI.展开更多
PEGylation is the gold standard for constructing protein resistance surfaces.Herein,grafting mPEG-SH and SH-PEG-SH with varied molecular weights(Mw=5K,10K,and 20K)on a gold chip,and the subsequent lysozyme adsorptions...PEGylation is the gold standard for constructing protein resistance surfaces.Herein,grafting mPEG-SH and SH-PEG-SH with varied molecular weights(Mw=5K,10K,and 20K)on a gold chip,and the subsequent lysozyme adsorptions of the PEG layers are evaluated using quartzcrystal microbalance based on dissipation(QCM-D).The lysozyme resistance depends on the features of grafting density and chain conformation,i.e.,linear and looped conformation.However,long-chain PEG(Mw≥10K)is insufficient to form a dense layer to resist protein due to large steric hindrances.Short-chain PEG(Mw=1K)with linear and looped structures is used to refill onto the long-chain PEG layer to increase the grafting density of PEGs and improve protein resistance.The refilling process and the subsequent protein adsorption depend on conformation rather than the density of the long-chain PEG substrate.Notably,the long-chain PEG looped substrates significantly improve protein resistance,attributing to the high viscoelasticity of the looped substrate and an increase in grafting density after refilling.Thus,refilling short-chain PEG improves protein resistance and the substrate conformation-dependence gives insight into the impact of topology,providing new ideas for how to increase chain density and select suitable topology to resist protein adsorption and demonstrating a potential application in biomedical fields.展开更多
In all-polymer solar cells(APSCs),number-average molecular weights(Mns)of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance.In this work,based on a ser...In all-polymer solar cells(APSCs),number-average molecular weights(Mns)of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance.In this work,based on a series of APSCs with power conversion efficiency of approaching 10%,we study the effect of Mns of both polymer donor and polymer acceptor on active layer morphology and photovoltaic performance of APSCs.We select poly[4-(5-(4,8-bis(5-((2-butyloctyl)thio)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b’]dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-7-(5-methylthiophen-2-yl)-2 H-benzo[d][1,2,3]triazole](CD1)as the polymer donor and poly[4-(5-(5,10-bis(2-dodecylhexadecyl)-4,4,9,9-tetrafluuoro-7-methyl-4,5,9,10-tetrahydro3 a,5,8,10-tetraaza-4,9-diborapyren-2-yl)thiophen-2-yl)-7-(5-methylthiophen-2-yl)benzo[c][1,2,5]thiadiazole](PBN-14)as the polymer acceptor.The Mns of polymer donor CD1 are 14.0,35.5 and 56.1 kg/mol,respectively,and the Mns of polymer acceptor PBN-14 are 32.7,72.4 and 103.4 kg/mol,respectively.To get the desired biscontinueous fibrous network morphololgy of the polymer donor/polymer acceptor blends,at least one polymer should have high or medium Mn.Moreover,when the Mn of polymer acceptor is high,the active layer morphology and APSC device performance are insensitive to the Mn of polymer donor.The optimal APSC device performance is obtained when the Mn of both the polymer donor and the polymer acceptor are medium.These results provide a comprehensive and deep understanding on the interplay and the effect of Mn of polymer donors and polymer acceptors in highperformance APSCs.展开更多
Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy a...Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy and renewable electricity.As a key component,efficient oxygen electrocatalyst for promoting sluggish reaction kinetics of oxygen reduction and evolution reaction(ORR and OER)under harsh operation conditions severely limited progress of these devices.Among various candidates,Ptgroup(Pt,Ir,and Ru)-based electrocatalysts are still the most active ORR/OER catalysts.However,the scarcity,high cost,and questionable stability restrict the widespread applications and the commercialization of PEMWE/PEMFC.Progresses in synthesizing atomically dispersed single/multiple-atom catalysts(SACs/MACs)offer new opportunities to Pt-group ORR/OER catalysts owing to nearly 100% metal utilization and high catalytic activities.Extensive efforts have been continuously devoted to optimizing the local structure of Pt-group OER/ORR catalysts at atom-level for further enhancing stability and activity.In this review,universal synthesis methods to prepare Ptgroup SACs are discussed first,highlighting crucial factors which affect the structure and catalytic performance.Afterward,advanced characterization techniques for directly confirming atomic dispersed metal atoms were introduced,including aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy.Importantly,considerations for rational catalyst design and typical Pt-group SACs/MACs are summarized regarding the regulation strategy of atomically dispersed metal sites and various supports,and effects of metal-support interaction on the catalytic performance.Finally,key challenges and proposed perspectives for future development of atomically dispersed Pt-group oxygen electrocatalysts for fuel cell and electrolyzer are briefly discussed.展开更多
Using a hybrid simulation approach that combines a finite difference method with a Brownian dynamics,we investigated the motion of charged polymers.Owing to the fact that polymer-solution systems often contain a large...Using a hybrid simulation approach that combines a finite difference method with a Brownian dynamics,we investigated the motion of charged polymers.Owing to the fact that polymer-solution systems often contain a large number of particles and the charged palymer chains are in a state of random motion,it is a time consuming task to calculate the electrostatic interaction of the system.Accordingly,we propose a new strategy to shorten the CPU time by reducing the iteration area.Our simulation results ilustrate the effect of preset parameters on CPU time and accuracy,and demonstrate the feasibility of the"local iteration"method.Importantly,we find that the increase in the number of charged beads has no signifiant infuence on the time of global iterations and local iterations.For a number of 80×80×80 grids,when the relative error is controlled below 1.5%,the computational efficiency is increased by 8.7 times in the case that contains 500 charged beads.In adition,for a number of 100×100×100 grids with 100 charged beads,the computational efciency can be increased up to 12 times.Our work provides new insights for the optimization of iterative algorithms in special problems.展开更多
Molecular doping is one of the most important tools to manipulate the electrical properties of conjugated polymers for application in organic optoelectronics.The polymer crystallinity and distribution position of the ...Molecular doping is one of the most important tools to manipulate the electrical properties of conjugated polymers for application in organic optoelectronics.The polymer crystallinity and distribution position of the dopant crucially determine electrical conductivity of the doped polymer.However,in solution-mixed doping,the interplay between polymer and dopant leads to highly structural disorder of polymer and random arrangement of dopant.Here,we propose a strategy to ensure the dopant induced polarons have high charge dissociation and transport by letting the conjugated polymers aggregate in the marginal solvent solution by cooling it from higher temperature to room temperature.We select poly(3-hexylthiophene-2,5-diyl)(P3HT)solution doped by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ)as a model system.P3HT crystallizes in the marginal solvent,such as 1,1,2-trichloroethane(TCE)driven by the favorπ-πinteraction between planar polymer backbone.The dopant F4TCNQ enters the alkyl side chain region not theπ-πstacking region and thus guarantees high crystallinity and theπ-πinteraction of P3HT.This distribution of F4TCNQ which away from the polymer backbone to ensure higher charge dissociation and transport.Finally,we obtained a high conductivity value of 23 S/cm by doping P3HT with 20%F4TCNQ by using the marginal solvent,which is higher than doping P3HT with a disordered coil conformation in chlorobenzene(CB)of 7 S/cm,which the dopants enter both the alkyl side chain region and theπ-πstacking region.展开更多
Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused b...Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications.Recently,strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed.Among these,the two-dimensional Sb(2D-Sb)materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion.Nevertheless,the synthetic methods are usually tedious,and even the mechanism of these strategies remains elusive,especially how to obtain large-scale 2D-Sb materials.Herein,a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided.This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth,while concurrently reducing and coating a nitrogen-doped carbon layer.Compared to the reported methods,it is simpler,more efficient,and conducive to the production of composite nanosheets with uniform thickness(3–4 nm).The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g^(-1) at current densities of 100 mA g^(-1) and remains stable for more than 200 cycles.Through characterizations and molecular dynamic simulations,how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored,and detailed explanations are provided.These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.展开更多
基金Supported by the National Key Research and Development Program of Traditional Chinese Medicine Modernization Project,China(No.2023YFC3504000)the Science and Technology Development Project of Jilin Province,China(No.20240404043ZP)the Science and Technology Innovation Cooperation Project of Changchun Science and Technology Bureau and Chinese Academy of Sciences,China(No.23SH14)。
文摘In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.
基金supported by the National Natural Science Foundation of China,Fund for Distinguished Young Scholars(No.52325301)CAS Project for Young Scientists in Basic Research(YSBR-094)the National Natural Science Foundation of China,Basic Science Center Program(No.51988102).
文摘Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.
基金support from the Instrument Developing Project of the Chinese Academy of Sciences (No.YJKYYQ20210003)Natural Science Foundation of Jilin Province (No. 20210101402JC)support from the National Natural Science Foundation of China (No. 22204159)。
文摘For nano-collision, regulating the interaction between nanoparticles(NPs) and electrode interfaces is crucial for the precise analysis of individual NPs. However, existing ultramicroelectrodes(UMEs) suffer from narrow electrochemical window and poor electrode interface adhesion, severely hindering the application of precise single NP analysis. Here, we propose a simple and effective interface modification strategy. By electrochemically self-assembling poly(diallyldimethylammonium chloride)(PC) on the surface of carbon nanocone electrodes(CNCEs), we successfully prepared PC-modified CNCEs(PC–CNCEs). These electrodes not only possess sufficiently wide electrochemical window but also exhibit strong adhesion to negatively charged Ag NPs on their surfaces. Surface physical analysis and electrochemical molecule detection validated the high-density loading of PC on the modified electrodes. Furthermore, the working principle of PC–CNCEs for single Ag NP collision detection was further verified through the techniques of nanocollision and double-potential steps. Leveraging these significant advantages, PC–CNCEs not only achieved precise measurements of single or mixed-sized Ag NPs but also detected Ag NP solutions at concentrations as low as fmol/L levels. This advancement offers a new strategy for the rapid and precise analysis of NP colloids.
基金financially supported by the National Natural Science Foundation of China(Nos.22341304,22341303 and 22103079)National Key R&D Program of China(Nos.2020YFA0713601 and 2023YFA1008800)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDC0180303)Fundamental Enhancement Program(No.2024-JCJQ-JJ-0247)。
文摘Shear banding in entangled polymer melts remains a fundamental yet unresolved phenomenon in nonlinear polymer rheology.Here,we perform molecular dynamics simulations of bidisperse entangled melts—comprising equal numbers of chains with lengths N=200 and N=400—to uncover the structural origins and dynamic evolution of shear banding.This bidisperse system amplifies spatial heterogeneities in the entanglement network and facilitates direct comparison with monodisperse melts of N=300,revealing quantitatively consistent steady-state shear stress versus shear rate responses.Notably,a pronounced stress plateau spanning over an order of magnitude in shear rate is observed,within which shear banding emerges reproducibly across independent simulations,as confirmed by systematic velocity profile and interface position analyses.Our findings challenge the prevailing notion that shear banding arises solely from dynamic flow instabilities.Instead,we establish a microstructure-driven framework,demonstrating that shear band nucleation is governed by pre-existing structural heterogeneities—specifically,localized weakening of the entanglement network at short-chain-enriched“soft spots”,indicative of a robust microstructural memory effect.During shear start-up,short chains preferentially disentangle and migrate along the shear direction;beyond a critical strain,long chains retract and redistribute away from the fast shear band center to minimize elastic energy.This chain-length-dependent migration dynamically enriches the shear band in short chains,stabilizing its structure and revealing a molecular mechanism that links entanglement heterogeneity to macroscopic flow localization.By bridging molecular-scale structural features with nonlinear rheological responses,this work offers a complementary perspective to classical tube and convective constraint release(CCR)models,highlighting the critical interplay between microstructural heterogeneity and chain migration in the onset and persistence of shear banding.
基金The National Key R&D Program of China(No.2022YFE0113000)the National Science Fund for Distinguished Young Scholars(No.22025406)+1 种基金the National Natural Science Foundation of China(Nos.22074138,12174457)the Youth Innovation Promotion Association of CAS(No.2020233)for financial support。
文摘Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.
基金financially supported by the National Natural Science Foundation of China(No.52422301)Natural Science Foundation of Jilin Province(No.SKL202302033)。
文摘The crystallization behavior of two commercial polyolefin elastomer(POE)samples was investigated using the fast scanning chip calorimetry(FSC)technique.Non-isothermal crystallization of the POE samples during cooling to low temperatures cannot be inhibited under the largest efficient cooling rate employed in the current work.Thus,the isothermal crystallization of POE samples was limited to a narrow temperature range.When the POE samples were cooled to a certain temperature below the non-isothermal crystallization temperature for crystallization,a crystallization time dependent melting peak appeared in the low temperature region besides the high temperature melting peak originated from the non-isothermal crystallization.This low temperature melting peak was arisen from the melting of crystals isothermally crystallized at the selected crystallization temperature.At each crystallization temperature,the lengths of crystallizable segments were different,thus,the low melting peak increased with increasing the crystallization temperature.In terms of the high melting peak attributed to the non-isothermally crystallized crystals,it somehow decreased with increasing crystallization time and then became constant with further increasing crystallization time at the selected crystallization temperature.This could be explained by the fact that the crystallizable sequences with longer length would nucleate and crystallize first to form thicker crystals during cooling.The subsequent crystallization contributed by the shorter crystallizable sequences will result in the formation of thinner crystals,causing the melting peak to shift to the lower temperature.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA 0400301)the National Key R&D Program of China(No.2022YFB4002000)+3 种基金the National Natural Science Foundation of China(No.22232004)the Instrument Developing Project of the Chinese Academy of Sciencesthe Jilin Province Development and Reform Commission Program(2023C032-6)the Jilin Province Science and Technology Development Program(No.20240302002ZD,20240101019JC and 20210502002ZP)for financial support。
文摘The development of robust and active oxygen evolution reaction(OER)electrocatalysts is urgently desirable for the widespread implementation of proton exchange membrane water electrolyzers(PEMWE),yet remains a critical challenge.We propose a catalyst named U-IrRuO_(x)@IrRu(where“U”denotes“ultrathin”),which features a spontaneously formed amorphous oxide shell that synergistically optimizes the electronic structure and corrosion resistance.Combined experimental and theoretical studies reveal that the oxyphilic Ru-induced electronic modulation weakens Ir-O binding strength,thereby accelerating the rate-determining step of ^(*)OOH formation.In addition,the metallic alloy core functions as an electron reservoir,suppressing excessive oxidation of active sites while ensuring high conductivity.Due to these attributes,the U-IrRuO_(x)@IrRu demonstrates a low overpotential of 230 mV at 10 mA cm^(-2),outperforming commercial IrO_(2)(CM)by 65 mV.When integrated into a PEMWE with an ultra-low Ir loading of 0.25 mg_(Ir)cm^(-2),it delivers an industrial current density of 2 A cm^(-2)at 1.74 V and 3 A cm^(-2)at 1.836 V,surpassing the U.S.Department of Energy(DOE)2025 target.More impressively,the U-IrRuOx@IrRubased electrolyzer can stably operate for over 550 h,with an extremely low decay rate of 7.52μV h^(-1),corresponding to a predicted lifespan of 23,000 h with 90%performance retention.
文摘Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.
基金financially supported by the National Key R&D Program of China (No. 2021YFA1501700)the National Natural Science Foundation of China+1 种基金Basic Science Center Program (No.51988102)the National Natural Science Foundation of China (No. 52073272)
文摘Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.
基金financially supported by the National Natural Science Foundation of China(21975251)。
文摘Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graphite intercalation compounds (AGICs) have been coming into their own in dual-ion batteries [1]. It is imperative to deepen an understanding of anion storage mechanisms in graphite electrode.
基金financially supported by the National Natural Science Foundation of China (Nos. 21634007 and 51773193)the Department of Science and Technology of Jilin Province(No. 20180101171JC)。
文摘Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.
基金Project supported by the National Natural Science Foundation of China (92262301)the National Key Research and Development Project of China (2022YFC2905201)+1 种基金the Strategic Priority Research Program of CAS(XDA02030100)Jiangxi "Double Thousand Plan"(JXSQ2020101005)。
文摘The efficient enrichment and separation of rare earth elements(REEs) from sulfate leachates of ionadsorption type rare earth ore(IATREO) is still a challenge.This work presents a novel extractant 2-(bis((2-ethylhexyl)oxy)phosphoryl)-2-hydroxyacetic acid(HPOAc) for the selective extraction and efficie nt enrichment of REEs from sulfate leachates of IATREO.HPOAc exhibits higher extraction ability for all fifteen REEs(Ⅲ) than naphthenic acid(NA) at pH_(ini)=1,56.Furthermore,it has no drawbacks of di-(2-ethylhexyl) phosphoric acid(P204) and 2-ethylhexyl phosphoric acid mono-2-ethylhexylester(P507)such as weak extraction ability towards light REEs(Ⅲ) and high stripping acidity for heavy REEs(Ⅲ).It has better separation performance for metal ion impurities than P204 and P507,especially for the typical impurity Al(Ⅲ).Furthermore,the HPOAc system has better phase separation behavior and extraction pheno mena.A simulated operation with two-stage counte r-current extraction and single-stage stripping of REEs was carried out using unsaponified HPOAc.The recovery of REEs reaches 98.7%.The concentration of REEs increases from 0.44 to 130.35 g/L,indicating a nearly 300-fold increase.Furthermore,the content of REEs increases from 77.8 wt% to 97.6 wt%.So HPOAc has the potential to selectively recover REEs from sulfate leachates of IATREO.
基金financially supported by the National Natural Science Foundation of China (No. 22161132007)BASF within the framework of NAO (Network for Advanced Materials Open Research)。
文摘The microstructural evolution of a thermoplastic polyurethane(TPU)with low hard segment content has been monitored utilizing in situ real-time synchrotron small angle X-ray scattering(SAXS)and time-domain nuclear magnetic resonance(NMR)measurements.The TPU is composed of 23 wt% of[4,4-methylenediphenyl diisocyanate(MDI)]-[1,4-butanediol(BD)]chain segments,which form hard domains,as[polytetrahydrofuran(PTHF)]forming soft domains.The number and distribution of monomer units in hard blocks is determined by the successive self-nucleation and annealing thermal fractionation technique.In situ SAXS method reveals heating-induced increase in the spacing of hard and soft domains,while time-domain ^(1)H-NMR characterizes the changes in the phase composition and chain dynamics in these domains.A glassy fraction of short MDI-BD chain segments in hard domains passes through T_(g) above ambient temperature.At higher temperatures,MDI-BD nanocrystals start to melt.Sequence length distribution of MDI-BD chain segments causes a distribution in crystal sizes and wide melting temperature range.The melting is accompanied by the mixing of MDI-BD with PTHF segments in soft domains,and by increase in segmental mobility in these domains.Above 180℃,the TPU melt is homogeneous on the scale above nanometers according to SAXS data.
基金financially supported by National Key Research and Development Program of China(No.2021YFB3800900)the National Natural Science Foundation of China(Nos.51925305,51833010 and 52203183)+2 种基金Natural Science Foundation of Xiamen,China(No.3502Z202371004)Fundamental Research Funds for the Central Universities(No.20720230004)the talent cultivation project Funds for the Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(No.HRTP-[2022]52)。
文摘Polyethyleneimine(PEI),as a widely used polymer material in the field of gene delivery,has been extensively studied for modification and shielding to reduce its cytotoxicity.However,research aimed at preparing degradable PEI is scarce.In this work,the hydrogen peroxide(H_(2)O_(2))oxidation method was used to introduce degradable amide groups in the PEI and a series of oxidized PEI22k(oxPEI22k)with different degrees of oxidation were synthesized by regulating the dosage of H_(2)O_(2).The relationship between the oxidation degree of oxPEI22k and the gene transfection efficiency of oxPEI22k was studied in detail,confirming that the oxPEI22k with oxidation degrees of 16.7%and 28.6%achieved improved transfection efficiency compared to unmodified PEI.These oxPEI22k also proved reduced cytotoxicity and improved degradability.Further,this strategy was extended to the synthesis of low-molecular-weight oxPEI1.8k.The oxPEI1.8k with suitable oxidation degree also achieved improved transfection efficiency and reduced cytotoxicity.In brief,this work provided high-efficiency and low-cytotoxicity degradable gene delivery carriers by regulating the oxidation degree of PEI,which was of great significance for promoting clinical applications of PEI.
基金financially supported by the National Natural Science Foundation of China(No.52073276)Changchun Science and Technology Development Program(No.21ZY07)the Innovation and Entrepreneurship Talent Project of Jilin Province.
文摘PEGylation is the gold standard for constructing protein resistance surfaces.Herein,grafting mPEG-SH and SH-PEG-SH with varied molecular weights(Mw=5K,10K,and 20K)on a gold chip,and the subsequent lysozyme adsorptions of the PEG layers are evaluated using quartzcrystal microbalance based on dissipation(QCM-D).The lysozyme resistance depends on the features of grafting density and chain conformation,i.e.,linear and looped conformation.However,long-chain PEG(Mw≥10K)is insufficient to form a dense layer to resist protein due to large steric hindrances.Short-chain PEG(Mw=1K)with linear and looped structures is used to refill onto the long-chain PEG layer to increase the grafting density of PEGs and improve protein resistance.The refilling process and the subsequent protein adsorption depend on conformation rather than the density of the long-chain PEG substrate.Notably,the long-chain PEG looped substrates significantly improve protein resistance,attributing to the high viscoelasticity of the looped substrate and an increase in grafting density after refilling.Thus,refilling short-chain PEG improves protein resistance and the substrate conformation-dependence gives insight into the impact of topology,providing new ideas for how to increase chain density and select suitable topology to resist protein adsorption and demonstrating a potential application in biomedical fields.
基金financially supported by the National Key Research and Development Program of China(Nos.2018YFE0100600 and 2019YFA0705902)funded by the Ministry of Science and Technology and the National Natural Science Foundation of China(Nos.21625403 and 21875244)。
文摘In all-polymer solar cells(APSCs),number-average molecular weights(Mns)of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance.In this work,based on a series of APSCs with power conversion efficiency of approaching 10%,we study the effect of Mns of both polymer donor and polymer acceptor on active layer morphology and photovoltaic performance of APSCs.We select poly[4-(5-(4,8-bis(5-((2-butyloctyl)thio)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b’]dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-7-(5-methylthiophen-2-yl)-2 H-benzo[d][1,2,3]triazole](CD1)as the polymer donor and poly[4-(5-(5,10-bis(2-dodecylhexadecyl)-4,4,9,9-tetrafluuoro-7-methyl-4,5,9,10-tetrahydro3 a,5,8,10-tetraaza-4,9-diborapyren-2-yl)thiophen-2-yl)-7-(5-methylthiophen-2-yl)benzo[c][1,2,5]thiadiazole](PBN-14)as the polymer acceptor.The Mns of polymer donor CD1 are 14.0,35.5 and 56.1 kg/mol,respectively,and the Mns of polymer acceptor PBN-14 are 32.7,72.4 and 103.4 kg/mol,respectively.To get the desired biscontinueous fibrous network morphololgy of the polymer donor/polymer acceptor blends,at least one polymer should have high or medium Mn.Moreover,when the Mn of polymer acceptor is high,the active layer morphology and APSC device performance are insensitive to the Mn of polymer donor.The optimal APSC device performance is obtained when the Mn of both the polymer donor and the polymer acceptor are medium.These results provide a comprehensive and deep understanding on the interplay and the effect of Mn of polymer donors and polymer acceptors in highperformance APSCs.
基金supported by the National Key Research and Development Program of China(No.2021YFB4000603)the National Natural Science Foundation of China(Nos.52273277 and U24A2062)+2 种基金Jilin Province Science and Technology Development Plan Funding Project(No.SKL202302039)Youth Innovation Promotion Association CAS(No.2021223)funding from National Natural Science Foundation of China Outstanding Youth Science Foundation of China(Overseas).
文摘Proton-exchange membrane fuel cell and water electrolyzer(PEMFC and PEMWE)with high conversion efficiency and zero-carbon emission stand out as an attractive strategy for efficient conversion between hydrogen energy and renewable electricity.As a key component,efficient oxygen electrocatalyst for promoting sluggish reaction kinetics of oxygen reduction and evolution reaction(ORR and OER)under harsh operation conditions severely limited progress of these devices.Among various candidates,Ptgroup(Pt,Ir,and Ru)-based electrocatalysts are still the most active ORR/OER catalysts.However,the scarcity,high cost,and questionable stability restrict the widespread applications and the commercialization of PEMWE/PEMFC.Progresses in synthesizing atomically dispersed single/multiple-atom catalysts(SACs/MACs)offer new opportunities to Pt-group ORR/OER catalysts owing to nearly 100% metal utilization and high catalytic activities.Extensive efforts have been continuously devoted to optimizing the local structure of Pt-group OER/ORR catalysts at atom-level for further enhancing stability and activity.In this review,universal synthesis methods to prepare Ptgroup SACs are discussed first,highlighting crucial factors which affect the structure and catalytic performance.Afterward,advanced characterization techniques for directly confirming atomic dispersed metal atoms were introduced,including aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy.Importantly,considerations for rational catalyst design and typical Pt-group SACs/MACs are summarized regarding the regulation strategy of atomically dispersed metal sites and various supports,and effects of metal-support interaction on the catalytic performance.Finally,key challenges and proposed perspectives for future development of atomically dispersed Pt-group oxygen electrocatalysts for fuel cell and electrolyzer are briefly discussed.
基金the National Natural!Science Foundation of China(No.21604086)Jilin Provincial science and technology development program(No.20190103124JH)Key Research Program of Frontier Sciences,CAS(No.QYZDY-SSW-SLH027).
文摘Using a hybrid simulation approach that combines a finite difference method with a Brownian dynamics,we investigated the motion of charged polymers.Owing to the fact that polymer-solution systems often contain a large number of particles and the charged palymer chains are in a state of random motion,it is a time consuming task to calculate the electrostatic interaction of the system.Accordingly,we propose a new strategy to shorten the CPU time by reducing the iteration area.Our simulation results ilustrate the effect of preset parameters on CPU time and accuracy,and demonstrate the feasibility of the"local iteration"method.Importantly,we find that the increase in the number of charged beads has no signifiant infuence on the time of global iterations and local iterations.For a number of 80×80×80 grids,when the relative error is controlled below 1.5%,the computational efficiency is increased by 8.7 times in the case that contains 500 charged beads.In adition,for a number of 100×100×100 grids with 100 charged beads,the computational efciency can be increased up to 12 times.Our work provides new insights for the optimization of iterative algorithms in special problems.
基金financially supported by the National Natural Science Foundation of China(No.51933010)。
文摘Molecular doping is one of the most important tools to manipulate the electrical properties of conjugated polymers for application in organic optoelectronics.The polymer crystallinity and distribution position of the dopant crucially determine electrical conductivity of the doped polymer.However,in solution-mixed doping,the interplay between polymer and dopant leads to highly structural disorder of polymer and random arrangement of dopant.Here,we propose a strategy to ensure the dopant induced polarons have high charge dissociation and transport by letting the conjugated polymers aggregate in the marginal solvent solution by cooling it from higher temperature to room temperature.We select poly(3-hexylthiophene-2,5-diyl)(P3HT)solution doped by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ)as a model system.P3HT crystallizes in the marginal solvent,such as 1,1,2-trichloroethane(TCE)driven by the favorπ-πinteraction between planar polymer backbone.The dopant F4TCNQ enters the alkyl side chain region not theπ-πstacking region and thus guarantees high crystallinity and theπ-πinteraction of P3HT.This distribution of F4TCNQ which away from the polymer backbone to ensure higher charge dissociation and transport.Finally,we obtained a high conductivity value of 23 S/cm by doping P3HT with 20%F4TCNQ by using the marginal solvent,which is higher than doping P3HT with a disordered coil conformation in chlorobenzene(CB)of 7 S/cm,which the dopants enter both the alkyl side chain region and theπ-πstacking region.
基金financially supported by the Science and Technology Development Program of Jilin Province(YDZJ202101ZYTS185)the National Natural Science Foundation of China(21975250)。
文摘Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications.Recently,strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed.Among these,the two-dimensional Sb(2D-Sb)materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion.Nevertheless,the synthetic methods are usually tedious,and even the mechanism of these strategies remains elusive,especially how to obtain large-scale 2D-Sb materials.Herein,a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided.This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth,while concurrently reducing and coating a nitrogen-doped carbon layer.Compared to the reported methods,it is simpler,more efficient,and conducive to the production of composite nanosheets with uniform thickness(3–4 nm).The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g^(-1) at current densities of 100 mA g^(-1) and remains stable for more than 200 cycles.Through characterizations and molecular dynamic simulations,how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored,and detailed explanations are provided.These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.
