Highly branched poly(β-amino ester)s(HPAEs)have emerged as a safe and efficient type of non-viral gene delivery vectors.However,the presence of inactive terminal secondary amine groups compromises their gene transfec...Highly branched poly(β-amino ester)s(HPAEs)have emerged as a safe and efficient type of non-viral gene delivery vectors.However,the presence of inactive terminal secondary amine groups compromises their gene transfection capability.In this study,HPAEs with similar topological structures and chemical compositions but varying numbers of terminal secondary 4-amino-1-butanol(S4)and secondary/tertiary 3-morpholinopropylamine(MPA)groups were synthesized.The results demonstrate that an increased number of secondary/tertiary MPA groups in-situ significantly enhances the DNA binding capability of HPAEs,leading to the formation of smaller HPAE/DNA polyplexes with higher zeta potential,ultimately resulting in superior gene transfection efficiency in bladder epithelial cells.This study establishes a sim-ple yet effective strategy to maximize the gene transfection potency of HPAEs by converting the inactive terminal groups in-situ without the need for complex modifications to their topological structure and chemical composition.展开更多
The surface charge properties and local dipole moment of terminal groups have a significant impact on molecular packing and aggregation performance of non-fullerene acceptors(NFAs)for organic solar cells(OSCs).Here,we...The surface charge properties and local dipole moment of terminal groups have a significant impact on molecular packing and aggregation performance of non-fullerene acceptors(NFAs)for organic solar cells(OSCs).Here,we utilize the interactions between different building blocks within the molecule to regulate the dipole asymmetry of terminal groups by introducing asymmetric inner side chains.Three NFAs,BTA80,BTA81 and BTA82 are designed and synthesized with different substitutions of benzotriazole(BTA)-based inner side chains.The asymmetric introduction of BTA-based inner side chains can modulate the asymmetric surface electrostatic potential and local dipole moments of the terminal groups through the interactions between BTA and the terminal groups,which in turn modifies the molecular orientation and enhances molecular packing.As the result,D18:BTA82-based OSCs achieve the champion power conversion efficiency(PCE)of 17.70%compared to D18:BTA80 and D18:BTA81-based devices with PCE of 16.06%and 16.65%,respectively.Moreover,by introducing the BTA82 as the third component into D18:L8-BO system,the ternary device exhibits a significant improved PCE of 19.60%compared to the device based D18:L8-BO(PCE of 18.73%).This work provides a novel insight into the design of asymmetric NFAs for high performance OSCs.展开更多
Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative s...Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative systems has been studied by means of UV, XPS, ^(13) C NMR and quantum chemical calculation. The results show that: 1. There exists the effect of opposite terminal groups exists in phenylpolyenic and other aromatic conjugative systems. 2. When A=B and X=Y are the same, the group (-X=Y) connected at polyenic chain is a terminal group, while the other is an opposite terminal group. When the two groups are different, the one with weaker conjugative power plays the role of the opposite terminal group. 3. The effect of opposite terminal groups increases successively in the order of CN, COMe, CHO, NO_2 and can be quantita- tively described with substitute equivalent △N_s. Theλ_(max) of compound containing an opposite terminal group can be calculated by the homologous equation 10^(-4) =a+b/(1/2)^(2/N＇^(-S)_a), most of the calculated values are in agreement with experiment results.展开更多
MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal...MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.展开更多
The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide...The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.展开更多
Interfacial engineering has made an outstanding contribution to the development of high-efficiency perovskite solar cells(PSCs).Here,we introduce an effective interface passivation strategy via methoxysilane molecules...Interfacial engineering has made an outstanding contribution to the development of high-efficiency perovskite solar cells(PSCs).Here,we introduce an effective interface passivation strategy via methoxysilane molecules with different terminal groups.The power conversion efficiency(PCE)has increased from 20.97%to 21.97%after introducing a 3-isocyanatopropyltrimethoxy silane(IPTMS)molecule with carbonyl group,while a trimethoxy[3-(phenylamino)propyl]silane(PAPMS)molecule containing aniline group deteriorates the photovoltaic performance as a consequence of decreased open circuit voltage.The improved performance after IPTMS treatment is ascribed to the suppression of non-radiative recombination and enhancement of carrier transportation.In addition,the devices with carbonyl group modification exhibit outstanding thermal stability,which maintain 90%of its initial PCE after 1500 h exposure.This work provides a guideline for the design of passivation molecules aiming to deliver the efficiency and thermal stability simultaneously.展开更多
Aqueous zinc-ion batteries(AZIBs)show great potential for applications in grid-scale energy storage,given their intrinsic safety,cost effectiveness,environmental friendliness,and impressive electrochemical performance...Aqueous zinc-ion batteries(AZIBs)show great potential for applications in grid-scale energy storage,given their intrinsic safety,cost effectiveness,environmental friendliness,and impressive electrochemical performance.However,strong electrostatic interactions exist between zinc ions and host materials,and they hinder the development of advanced cathode materials for efficient,rapid,and stable Zn-ion storage.MXenes and their derivatives possess a large interlayer spacing,excellent hydrophilicity,outstanding electronic conductivity,and high redox activity.These materials are considered“rising star”cathode candidates for AZIBs.This comprehensive review discusses recent advances in MXenes as AZIB cathodes from the perspectives of crystal structure,Zn-storage mechanism,surface modification,interlayer engineering,and conductive network design to elucidate the correlations among their composition,structure,and electrochemical performance.This work also outlines the remaining challenges faced by MXenes for aqueous Zn-ion storage,such as the urgent need for improved toxic preparation methods,exploration of potential novel MXene cathodes,and suppression of layered MXene restacking upon cycling,and introduces the prospects of MXene-based cathode materials for high-performance AZIBs.展开更多
In this paper, we review our recent progress in the synthesis and application of styryl-capped polypropylene （PP-t- St）, an excellent reactive polyolefin that is both convenient and efficient in synthesis and facile...In this paper, we review our recent progress in the synthesis and application of styryl-capped polypropylene （PP-t- St）, an excellent reactive polyolefin that is both convenient and efficient in synthesis and facile and versatile in application for preparing advanced polypropylene materials via macromolecular engineering. The synthesis of PP-t-St is made possible by a unique chain transfer reaction coordinated by a bis-styrenic molecule, such as 1,4-divinylbenzene （DVB） and 1,2-bis（4- vinylphenyl）ethane （BVPE）, and hydrogen in typical C2-symmetric metallocene （e.g. rac-Me2Si（2-Me-4-Ph-Ind）2ZrC12, in association with methylaluminocene, MAO） catalyzed propylene polymerization. The regio-selective 2,1- insertion of the styrenic double bond in DVB or BVPE into the overwhelmingly 1,2-fashioned Zr-PP propagating chain enables substantial dormancy of the catalyst active site, which triggers selective hydrogen chain transfer that, with the formed Zr-H species ultimately saturated by the insertion of propylene monomer, results in an exclusive capping of the afforded PP chains by styryl group at the termination end. With a highly reactive styryl group at chain end, PP-t-St has been used as a facile building block in PP macromolecular engineering together with the employment of state-of-the-art synthetic polymer chemistry to fabricate broad types of new polypropylene architectures.展开更多
Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising coc...Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface area.The current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of photocatalysis.More specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review.The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail.Considering the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are discussed.Additionally,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental factors.The optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also included.Lastly,the review summarizes the conclusion and future perspectives for solar energy conversion applications.展开更多
Intimate understanding of the synthesis-structure-activity relationships is an accessible pathway to overcome the intrinsic challenges of carbon nitride(g-C_(3)N_(4))photocatalysts.This work looks in the effects of hu...Intimate understanding of the synthesis-structure-activity relationships is an accessible pathway to overcome the intrinsic challenges of carbon nitride(g-C_(3)N_(4))photocatalysts.This work looks in the effects of humidity of the synthesis process to the morphology,chemical structure,band structure as well as the photocatalytic activity of g-C_(3)N_(4) materials.Four g-C_(3)N_(4) samples were prepared by heating melem in four gas environments:dry Ar,dry Air,moist Ar and moist Air.The photocatalytic activity measurements revealed that the samples synthesized in moist inert and oxidic gases environments displayed 20 and 10 times the photocata lytic H_(2) evolution activity of the samples synthesized in dry inert and oxidic gases environments,respectively.The reasons for this remarkable variety in photocata lytic activities had been through investigated.After all,the terminations of the carbon vacancies were identified as the dominant factor in enhancing H_(2) evolution performance.The work here thus demonstrating an example of defect engineering.展开更多
Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synt...Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synthesis of DenPols with high-generation and well-defined structures.Herein,we report a“m+n”grafting-onto strategy combined with the copper-catalyzed azide-alkyne cycloaddition(CuAAC)reaction with reaction-enhanced reactivity of intermediates(RERI)mechanism for synthesizing DenPols G_(m+n) by attaching n-generation dendrons(G_(n))onto the m-generation DenPols G_(m).In this“m+n”grafting-onto strategy,the DenPols G_(m)(m=1,2)bearing 1,3-triazido branches on the repeating unit were capable of RERI effect that guaranteed the CuAAC reaction in an extremely efficient way with ultrafast kinetics to synthesize third-,fourth-and fifth-generation DenPols(G_(1+2),G_(1+3),G_(1+4),G_(2+2),and G_(2+3))with near quantitative grafting density and narrow distribution.Moreover,these resultant DenPols G_(m+n) had more terminal groups per repeating unit due to the three branches of 1,3-triazido structure,exhibiting valuable potential opportunities for molecular surface engineering.The development of this“m+n”grafting-onto strategy with RERI mechanism not only presents a new avenue for ultrafast preparing DenPols but also holds great promise for preparing unimolecular materials with more functional terminal groups.展开更多
Diruthenium ethynyl complexes 1--3 （1： 1,5-dithia-s-indacene-4,8-dione; 2： 4,8-diethoxybenzo[1,2-b：4,5- b＇]dithiophene; 3： 4,8-didodecyloxybenzo[1,2-b：4,5-b＇]dithiophene） have been synthesized by incorporatin...Diruthenium ethynyl complexes 1--3 （1： 1,5-dithia-s-indacene-4,8-dione; 2： 4,8-diethoxybenzo[1,2-b：4,5- b＇]dithiophene; 3： 4,8-didodecyloxybenzo[1,2-b：4,5-b＇]dithiophene） have been synthesized by incorporating the re- spective conjugated heterocyclic spacer and characterized by NMR and elemental analysis. The effects of bridge ligands＇ properties on electronic coupling between redox-active ruthenium terminal groups were investigated by electrochemistry, UV/vis/near-IR and IR spectroelectrochemistry combined with density functional theory （DFT） and time-dependent DFT calculations. Electrochemistry results indicated that complexes 1--3 exhibit two fully re- versible oxidation waves, and complexes 2 and 3 with electron-rich and π-conjuagted bridge ligands are character- ized by excellent electrochemical properties. Furthermore, the larger v（C≡C） separation from the IR spectroelec- trochemical results of 2 and 3 and the intense NIR absorption features of singly oxidized species 2＋ and 3＋ re- vealed that their molecular skeletons have superior abilities to delocalize the positive charge. The spin density dis- tribution from DFT calculations proved the conclusions of this study.展开更多
A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO)as the hydrophilic block and poly(ε-caprolactone)(PCL)as the hydrophobic block with the amino terminal group at the end of th...A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO)as the hydrophilic block and poly(ε-caprolactone)(PCL)as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2)were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH)and functional compounds RGD(PCL-b-PEO-RGD)as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM)were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC)and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD)into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.展开更多
Nanodiamond particles(NDPs)have been considered as a potential lubricant additive to various tribological applications,such as water lubrication systems.In this study,the tribological properties of silicon carbide(SiC...Nanodiamond particles(NDPs)have been considered as a potential lubricant additive to various tribological applications,such as water lubrication systems.In this study,the tribological properties of silicon carbide(SiC)lubricated by NDPs dispersed in water are investigated utilizing the ball-on-disk tribometer.It is found that the slight addition of NDP to water(i.e.,0.001 wt%)can distinctly accelerate the running-in process,which is necessary to achieve a friction coefficient(μ)as low as 0.01.This study also discusses two NDP functional terminations—hydroxyl and carboxyl.It is demonstrated that the use of carboxyl-terminated NDP over a wide range of concentration(0.001 wt%-1 wt%)yields a low friction force.In contrast,the ideal effective concentration of hydroxyl-terminated NDP is considerably limited because agglomeration in this material is more probable to occur than in the former.Meanwhile,when utilizing NDPs,the input friction energy(P_(in),defined as the product of sliding speed and applied load)is found to have an essential function.Several sliding tests were implemented at various P_(in) values(50-1,500 mW)using carboxyl-terminated water-dispersed NDPs.It was observed that theμand wear decreased with increasing P_(in) when 200 mW<P_(in)<1,500 mW.However,when P_(in)<200 mW,low friction with high wear occurs compared with the resulting friction and wear when pure water is used.展开更多
基金funded by the National Natural Science Foundation of China(NSFC,No.51903202)the Key R&D Program of Shaanxi Province(No.2020GXLH-Y-016)+2 种基金the Natural Science Foundation of Shaanxi Province(No.2020JM-055)the Fundamental Re-search Funds for the Central Universities(No.xtr042019020)the Young Talents Support Plan of Xi’an Jiaotong University(No.HG6J002).
文摘Highly branched poly(β-amino ester)s(HPAEs)have emerged as a safe and efficient type of non-viral gene delivery vectors.However,the presence of inactive terminal secondary amine groups compromises their gene transfection capability.In this study,HPAEs with similar topological structures and chemical compositions but varying numbers of terminal secondary 4-amino-1-butanol(S4)and secondary/tertiary 3-morpholinopropylamine(MPA)groups were synthesized.The results demonstrate that an increased number of secondary/tertiary MPA groups in-situ significantly enhances the DNA binding capability of HPAEs,leading to the formation of smaller HPAE/DNA polyplexes with higher zeta potential,ultimately resulting in superior gene transfection efficiency in bladder epithelial cells.This study establishes a sim-ple yet effective strategy to maximize the gene transfection potency of HPAEs by converting the inactive terminal groups in-situ without the need for complex modifications to their topological structure and chemical composition.
基金support from the National Natural Science Foundation of China(52303259,52373176).
文摘The surface charge properties and local dipole moment of terminal groups have a significant impact on molecular packing and aggregation performance of non-fullerene acceptors(NFAs)for organic solar cells(OSCs).Here,we utilize the interactions between different building blocks within the molecule to regulate the dipole asymmetry of terminal groups by introducing asymmetric inner side chains.Three NFAs,BTA80,BTA81 and BTA82 are designed and synthesized with different substitutions of benzotriazole(BTA)-based inner side chains.The asymmetric introduction of BTA-based inner side chains can modulate the asymmetric surface electrostatic potential and local dipole moments of the terminal groups through the interactions between BTA and the terminal groups,which in turn modifies the molecular orientation and enhances molecular packing.As the result,D18:BTA82-based OSCs achieve the champion power conversion efficiency(PCE)of 17.70%compared to D18:BTA80 and D18:BTA81-based devices with PCE of 16.06%and 16.65%,respectively.Moreover,by introducing the BTA82 as the third component into D18:L8-BO system,the ternary device exhibits a significant improved PCE of 19.60%compared to the device based D18:L8-BO(PCE of 18.73%).This work provides a novel insight into the design of asymmetric NFAs for high performance OSCs.
文摘Seven homologous series p-A=B-C_6H_4(CH=CH)_nX=Y (A=B: NO_2, X=Y: CHO, COMe, CN, NO_2; A=B: CN, X=Y: CHO, CN; A=B: H, X=Y: NO_2) were synthesized, the effect of opposite terminal groups in phenylpolyenic conjugative systems has been studied by means of UV, XPS, ^(13) C NMR and quantum chemical calculation. The results show that: 1. There exists the effect of opposite terminal groups exists in phenylpolyenic and other aromatic conjugative systems. 2. When A=B and X=Y are the same, the group (-X=Y) connected at polyenic chain is a terminal group, while the other is an opposite terminal group. When the two groups are different, the one with weaker conjugative power plays the role of the opposite terminal group. 3. The effect of opposite terminal groups increases successively in the order of CN, COMe, CHO, NO_2 and can be quantita- tively described with substitute equivalent △N_s. Theλ_(max) of compound containing an opposite terminal group can be calculated by the homologous equation 10^(-4) =a+b/(1/2)^(2/N＇^(-S)_a), most of the calculated values are in agreement with experiment results.
基金supported by the National Natural Science Foundation of China(21703147 and U1401248)the support of China Scholarship Council(2018SLJ022487)。
文摘MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.
基金supported by the National Natural Science Foundation of China(Nos.21375145,21221064)
文摘The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.
基金The authors acknowledge funding support from National Natural Science Foundation of China(21975028,22011540377)National Science Foundation for Young Scientists No.21805010,Beijing Municipal Science and Technology Project No.Z181100005118002,and Beijing Municipal Natural Science Foundation(JQ19008).
文摘Interfacial engineering has made an outstanding contribution to the development of high-efficiency perovskite solar cells(PSCs).Here,we introduce an effective interface passivation strategy via methoxysilane molecules with different terminal groups.The power conversion efficiency(PCE)has increased from 20.97%to 21.97%after introducing a 3-isocyanatopropyltrimethoxy silane(IPTMS)molecule with carbonyl group,while a trimethoxy[3-(phenylamino)propyl]silane(PAPMS)molecule containing aniline group deteriorates the photovoltaic performance as a consequence of decreased open circuit voltage.The improved performance after IPTMS treatment is ascribed to the suppression of non-radiative recombination and enhancement of carrier transportation.In addition,the devices with carbonyl group modification exhibit outstanding thermal stability,which maintain 90%of its initial PCE after 1500 h exposure.This work provides a guideline for the design of passivation molecules aiming to deliver the efficiency and thermal stability simultaneously.
基金the National Natural Science Foundation of China(Nos.52372171,22075016,and 52201201)the National Program for Support of Top-notch Young Professionals,China+3 种基金the Interdisciplinary Research Project for Young Teachers of University of Science and Technology Beijing,China(No.FRF-IDRY-21-011)the State Key Laboratory for Advanced Metals and Materials,China(No.2022Z-17)the Ministry of Education Social Science Project,China(No.18YJC790087)the“Xiaomi Young Scholar”Funding Project,China,and the 111 Project,China(No.B170003)。
文摘Aqueous zinc-ion batteries(AZIBs)show great potential for applications in grid-scale energy storage,given their intrinsic safety,cost effectiveness,environmental friendliness,and impressive electrochemical performance.However,strong electrostatic interactions exist between zinc ions and host materials,and they hinder the development of advanced cathode materials for efficient,rapid,and stable Zn-ion storage.MXenes and their derivatives possess a large interlayer spacing,excellent hydrophilicity,outstanding electronic conductivity,and high redox activity.These materials are considered“rising star”cathode candidates for AZIBs.This comprehensive review discusses recent advances in MXenes as AZIB cathodes from the perspectives of crystal structure,Zn-storage mechanism,surface modification,interlayer engineering,and conductive network design to elucidate the correlations among their composition,structure,and electrochemical performance.This work also outlines the remaining challenges faced by MXenes for aqueous Zn-ion storage,such as the urgent need for improved toxic preparation methods,exploration of potential novel MXene cathodes,and suppression of layered MXene restacking upon cycling,and introduces the prospects of MXene-based cathode materials for high-performance AZIBs.
基金supported by the National Natural Science Foundation of China (Nos. 20734002, 51103163,51003106 and 51003105)Chinese Academy of Sciences (Directional key project on high performance polypropylene alloy resin development)
文摘In this paper, we review our recent progress in the synthesis and application of styryl-capped polypropylene （PP-t- St）, an excellent reactive polyolefin that is both convenient and efficient in synthesis and facile and versatile in application for preparing advanced polypropylene materials via macromolecular engineering. The synthesis of PP-t-St is made possible by a unique chain transfer reaction coordinated by a bis-styrenic molecule, such as 1,4-divinylbenzene （DVB） and 1,2-bis（4- vinylphenyl）ethane （BVPE）, and hydrogen in typical C2-symmetric metallocene （e.g. rac-Me2Si（2-Me-4-Ph-Ind）2ZrC12, in association with methylaluminocene, MAO） catalyzed propylene polymerization. The regio-selective 2,1- insertion of the styrenic double bond in DVB or BVPE into the overwhelmingly 1,2-fashioned Zr-PP propagating chain enables substantial dormancy of the catalyst active site, which triggers selective hydrogen chain transfer that, with the formed Zr-H species ultimately saturated by the insertion of propylene monomer, results in an exclusive capping of the afforded PP chains by styryl group at the termination end. With a highly reactive styryl group at chain end, PP-t-St has been used as a facile building block in PP macromolecular engineering together with the employment of state-of-the-art synthetic polymer chemistry to fabricate broad types of new polypropylene architectures.
基金supported by United Arab Emirates University(UAEU),United Arab Emirates under research fund no 12N097。
文摘Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface area.The current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of photocatalysis.More specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review.The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail.Considering the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are discussed.Additionally,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental factors.The optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also included.Lastly,the review summarizes the conclusion and future perspectives for solar energy conversion applications.
基金financially supported by the National Natural Science Foundation of China(No.21777063,21676128)The Natural Science Foundation of Jiangsu Province(BK20180887)+1 种基金a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,High-tech Research Key Laboratory of Zhenjiang(SS2018002)The High Performance Computing Platform of Jiangsu University。
文摘Intimate understanding of the synthesis-structure-activity relationships is an accessible pathway to overcome the intrinsic challenges of carbon nitride(g-C_(3)N_(4))photocatalysts.This work looks in the effects of humidity of the synthesis process to the morphology,chemical structure,band structure as well as the photocatalytic activity of g-C_(3)N_(4) materials.Four g-C_(3)N_(4) samples were prepared by heating melem in four gas environments:dry Ar,dry Air,moist Ar and moist Air.The photocatalytic activity measurements revealed that the samples synthesized in moist inert and oxidic gases environments displayed 20 and 10 times the photocata lytic H_(2) evolution activity of the samples synthesized in dry inert and oxidic gases environments,respectively.The reasons for this remarkable variety in photocata lytic activities had been through investigated.After all,the terminations of the carbon vacancies were identified as the dominant factor in enhancing H_(2) evolution performance.The work here thus demonstrating an example of defect engineering.
基金the National Natural Science Foundation of China(Nos.22071271,22371313)Natural Science Foundation of Guangdong Province(2024A1515011133 and 2021A1515110853)the Fundamental Research Funds for the Central Universities(23yxqntd002).
文摘Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synthesis of DenPols with high-generation and well-defined structures.Herein,we report a“m+n”grafting-onto strategy combined with the copper-catalyzed azide-alkyne cycloaddition(CuAAC)reaction with reaction-enhanced reactivity of intermediates(RERI)mechanism for synthesizing DenPols G_(m+n) by attaching n-generation dendrons(G_(n))onto the m-generation DenPols G_(m).In this“m+n”grafting-onto strategy,the DenPols G_(m)(m=1,2)bearing 1,3-triazido branches on the repeating unit were capable of RERI effect that guaranteed the CuAAC reaction in an extremely efficient way with ultrafast kinetics to synthesize third-,fourth-and fifth-generation DenPols(G_(1+2),G_(1+3),G_(1+4),G_(2+2),and G_(2+3))with near quantitative grafting density and narrow distribution.Moreover,these resultant DenPols G_(m+n) had more terminal groups per repeating unit due to the three branches of 1,3-triazido structure,exhibiting valuable potential opportunities for molecular surface engineering.The development of this“m+n”grafting-onto strategy with RERI mechanism not only presents a new avenue for ultrafast preparing DenPols but also holds great promise for preparing unimolecular materials with more functional terminal groups.
基金The authors acknowledge financial support from Na- tional Natural Science Foundation of China （No. 21602049） and the Natural Science Foundation of Hu- nan Province, China （No. 2017JJ3004）.
文摘Diruthenium ethynyl complexes 1--3 （1： 1,5-dithia-s-indacene-4,8-dione; 2： 4,8-diethoxybenzo[1,2-b：4,5- b＇]dithiophene; 3： 4,8-didodecyloxybenzo[1,2-b：4,5-b＇]dithiophene） have been synthesized by incorporating the re- spective conjugated heterocyclic spacer and characterized by NMR and elemental analysis. The effects of bridge ligands＇ properties on electronic coupling between redox-active ruthenium terminal groups were investigated by electrochemistry, UV/vis/near-IR and IR spectroelectrochemistry combined with density functional theory （DFT） and time-dependent DFT calculations. Electrochemistry results indicated that complexes 1--3 exhibit two fully re- versible oxidation waves, and complexes 2 and 3 with electron-rich and π-conjuagted bridge ligands are character- ized by excellent electrochemical properties. Furthermore, the larger v（C≡C） separation from the IR spectroelec- trochemical results of 2 and 3 and the intense NIR absorption features of singly oxidized species 2＋ and 3＋ re- vealed that their molecular skeletons have superior abilities to delocalize the positive charge. The spin density dis- tribution from DFT calculations proved the conclusions of this study.
基金supported by the National Natural Science Foundation of China(Grant Nos 50873109 and 50830103)Chinese Academy of Sciences
文摘A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO)as the hydrophilic block and poly(ε-caprolactone)(PCL)as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2)were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH)and functional compounds RGD(PCL-b-PEO-RGD)as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM)were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC)and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD)into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.
文摘Nanodiamond particles(NDPs)have been considered as a potential lubricant additive to various tribological applications,such as water lubrication systems.In this study,the tribological properties of silicon carbide(SiC)lubricated by NDPs dispersed in water are investigated utilizing the ball-on-disk tribometer.It is found that the slight addition of NDP to water(i.e.,0.001 wt%)can distinctly accelerate the running-in process,which is necessary to achieve a friction coefficient(μ)as low as 0.01.This study also discusses two NDP functional terminations—hydroxyl and carboxyl.It is demonstrated that the use of carboxyl-terminated NDP over a wide range of concentration(0.001 wt%-1 wt%)yields a low friction force.In contrast,the ideal effective concentration of hydroxyl-terminated NDP is considerably limited because agglomeration in this material is more probable to occur than in the former.Meanwhile,when utilizing NDPs,the input friction energy(P_(in),defined as the product of sliding speed and applied load)is found to have an essential function.Several sliding tests were implemented at various P_(in) values(50-1,500 mW)using carboxyl-terminated water-dispersed NDPs.It was observed that theμand wear decreased with increasing P_(in) when 200 mW<P_(in)<1,500 mW.However,when P_(in)<200 mW,low friction with high wear occurs compared with the resulting friction and wear when pure water is used.
