The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal ...The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal nanoparticles aggregation during pyrolysis process. Herein, we reported the efficient synthesis of nitrogen doped carbon hollow nanospheres with cobalt nanoparticles （Co NP, ca. 10nm in size） distributed uniformly in the shell via pyrolysis of yolk-shell structured Zn-Co-ZIFs@polydopamine （PDA）. PDA acted as both protection layer and carbon source, which successfully prevented the aggregation of cobalt nanoparticles during high-temperature pyrolysis process. The Co NP and N containing carbon （Co NP/NC） hollow nanospheres were active for both oxygen evolution reaction （OER） and oxygen reduction reaction （ORR）, affording overpotential of 430 mV at 10 mA/cm2 for OER in 1 M KOH and comparable half-wave potential to that of Pt/C （0.80V vs RHE） for ORR in 0.1 M KOH. The superior performance of carbon hollow nanospheres for both OER and ORR was mainly attributed to its small metal nanoparticles, N-doping and hollow nanostructure. The protection and confinement effect that originated from PDA coating strategy could be extended to the synthesis of other hollow structured carbon materials, especially the ones with small metal nanoparticles.展开更多
Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to det...Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.展开更多
Background:Treatment of methicillin-resistant Staphylococcus aureus(MRSA)biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium(Ti)implants.There is a need to expl...Background:Treatment of methicillin-resistant Staphylococcus aureus(MRSA)biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium(Ti)implants.There is a need to explore more effective approaches for the treatment of MRSA biofilm infections.Methods:Herein,an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles(PDA),nitric oxide(NO)release donor sodium nitroprusside(SNP)and osteogenic growth peptide(OGP)onto Ti implants,denoted as Ti-PDA@SNP-OGP.The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy,X-ray photoelectron spectroscope,water contact angle,photothermal property and NO release behavior.The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2′,7′-dichlorofluorescein diacetate probe,1-N-phenylnaphthylamine assay,adenosine triphosphate intensity,O-nitrophenyl-β-D-galactopyranoside hydrolysis activity,bicinchoninic acid leakage.Fluorescence staining,assays for alkaline phosphatase activity,collagen secretion and extracellular matrix mineralization,quantitative real‑time reverse transcription‑polymerase chain reaction,and enzyme-linked immunosorbent assay(ELISA)were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells(MSCs),RAW264.7 cells and their co-culture system.Giemsa staining,ELISA,micro-CT,hematoxylin and eosin,Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms,inhibition of inflammatory response,and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo.Results:Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light(NIR)irradiation,and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species(ROS)-mediated oxidative stress,destroying bacterial membrane integrity and causing leakage of intracellular components(P<0.01).In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs,but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype(P<0.05 or P<0.01).The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways(P<0.01).In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model(P<0.01).Conclusions:Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.展开更多
Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced in...Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.展开更多
This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of ...This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to itsπ-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au40%electrode,with Faradaic efficiencies of 47.4%(110.5μM cm^(-2))and 27.8%(50.4μM cm^(-2))for methanol and methane,respectively.The performance of the photoelectrodes was shown to be Cu_(2)O facet-dependent,with cubic structures leading to greater conversion of CO_(2)to methanol(43%)and methane(27%),compared to the octahedral morphology,while a higher percentage of metallic gold on the nanostructured Cu_(2)O surface was mainly important for CH4production.Density functional theory(DFT)calculations supported these findings,attributing the superior photoelectrocatalytic performance of the TNT@PDA/Nc/Au40%electrode for CH4generation to the formation of an OCH3intermediate bonded to Au atoms.Studies using isotope-labeling and analysis by gas chromatograph-mass(GC-MS)demonstrated that13CO_(2)was the source for photoelectrocatalytic generation of13CH3OH and13CH313CH2OH.展开更多
The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate...The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.展开更多
The practical application of energetic materials, particularly 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20), is frequently impeded by phase transition challenges. In this study, we propose a novel...The practical application of energetic materials, particularly 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20), is frequently impeded by phase transition challenges. In this study, we propose a novel strategy to enhance the stability of CL-20 by employing a thermo-sensitive polymer,poly(N-isopropylacrylamide)(PNIPAM), to modulate its phase transitions. Our approach involves the use of an in-situ polymerized polydopamine(PDA) shell as a platform for surface grafting through atom transfer radical polymerization, yielding a core-shell structured CL-20@PDA-PNIPAM. Through comprehensive characterization, the successful grafting of PNIPAM is confirmed, significantly enhanced the phase stability of CL-20. Notably, our core-shell structure exhibits a 13℃ increase in phase transition temperature compared to raw CL-20, thereby delaying the ε→a phase transition by over 80 min under combined thermal and solvent conditions. The enhanced stability is attributed to the hydrophobic nature of PNIPAM above its low critical solution temperature in water, which effectively shields the CL-20 crystal. These findings provide new insights into enhancing the stability and safety of energetic materials in complex environments, highlighting the potential of our molecular switch mechanism.展开更多
The development of high-sulfur-loading Li-S batteries is a key prerequisite for their commercial applications.This requires to surmount the huge polarization,severe polysulfide shuttling and drastic volume change caus...The development of high-sulfur-loading Li-S batteries is a key prerequisite for their commercial applications.This requires to surmount the huge polarization,severe polysulfide shuttling and drastic volume change caused by electrode thickening.High-strength polar binders are ideal for constructing robust and long-life high-loading sulfur cathodes but show very weak interfacial interaction with non-polar sulfur materials.To address this issue,this work devises a highly integrated sulfur@polydopamine/highstrength binder composite cathodes,targeting long-lasting and high-sulfur-loading Li-S batteries.The super-adhesion polydopamine(PD)can form a uniform nano-coating over the graphene/sulfur(G-S)surface and provide strong affinity to the cross-linked polyacrylamide(c-PAM)binder,thus tightly integrating sulfur with the binder network and greatly boosting the overall mechanical strength/conductivity of the electrode.Moreover,the PD coating and c-PAM binder rich in polar groups can form two effective blockades against the effusion of soluble polysulfides.As such,the 4.5 mg cm−2 sulfur-loaded G-S@PD-c-PAM cathode achieves a capacity of 480 mAh g−1 after 300 cycles at 1 C,while maintaining a capacity of 396 mAh g−1 after 50 cycles at 0.2 C when the sulfur loading rises to 9.1 mg cm−2.This work provides a system-wide concept for constructing high-loading sulfur cathodes through integrated structural design.展开更多
Three-dimensional(3D)micro-jet printing is a droplet deposition technique based on liquid-phase materials.To improve the deposition density and performance of energetic films with micro/nanoscale on an energetic chip,...Three-dimensional(3D)micro-jet printing is a droplet deposition technique based on liquid-phase materials.To improve the deposition density and performance of energetic films with micro/nanoscale on an energetic chip,polydopamine(PDA)was utilized as a linker bridge to induce the in-situ self-assembly of CL-20-based energetic film via 3D micro-jet printing.The self-assembly was extensively characterized by confocal laser scanning microscopy(CLSM),SEM,power-XRD,XPS,and DSC.The performance of the self-assembled film was verified by the mechanical properties and detonation properties,and a possible self-assembly mechanism in the layer-by-layer micro-jet printing process was proposed.The results indicated PDA-induced self-assembly enhanced the physical entanglement between the binders and energetic crystal,reduced the porosity from 15.87%to 11.28%,and improved the elastic modulus and the detonation performance of the CL-20-based energetic film.This work proposes a novel and promising energetic film design and fabrication strategy to enhance the interaction between the energetic composite layers in the micro-jet printing process.展开更多
Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,fol...Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,followed by carbonization of polydopamine(PODA)to form a carbon shell,and finally partial etching of the nanostructured Si core by NaOH solution at elevated temperatures.In particular,the effects of ball milling time and NaOH etching temperature on the electrochemical properties of Si/Gr@void@C are investigated.Increasing the ball milling time results in the improved specific capacity of Si-based anodes.Carbon coating further enhances the specific capacity and capacity retention over charge/discharge cycles.The best cycle stability is achieved after partial etching of the Si core inside Si/Gr@void@C particles at either 70 or 80C,leading to little or no capacity decay over 130 cycles.However,it is found that both carbon coating and NaOH etching processes cause some surface oxidation of the nanostructured Si particles derived from high-energy ball milling.The surface oxidation of the nanostructured Si results in decreases in specific capacity and should be minimized in future studies.The mechanistic understanding developed in this study paves the way to further improve the electrochemical performance of Si/Gr@void@C nanocomposites in future.展开更多
Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In ...Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In order to obtain high-quality HMX@PDA-based PBX explosives with high sphericity and a narrow particle size distribution,composite microspheres were prepared using co-axial droplet microfluidic technology.The formation mechanism,thermal behavior,mechanical sensitivity,electrostatic spark sensitivity,compressive strength,and combustion performance of the microspheres were investigated.The results show that PDA can effectively enhance the interfacial interaction between the explosive particles and the binder under the synergistic effect of chemical bonds and the physical"mechanical interlocking"structure.Interface reinforcement causes the thermal decomposition temperature of the sample microspheres to move to a higher temperature,with the sensitivity to impact,friction,and electrostatic sparks(for S-1)increasing by 12.5%,31.3%,and 81.5%respectively,and the compressive strength also increased by 30.7%,effectively enhancing the safety performance of the microspheres.Therefore,this study provides an effective and universal strategy for preparing high-quality functional explosives,and also provides some reference for the safe use of energetic materials in practical applications.展开更多
文摘The pyrolysis under inert atmosphere has been widely used for the synthesis of metal containing heteroatoms doped carbon materials, versatile catalysts for various reactions. However, it is difficult to prevent metal nanoparticles aggregation during pyrolysis process. Herein, we reported the efficient synthesis of nitrogen doped carbon hollow nanospheres with cobalt nanoparticles （Co NP, ca. 10nm in size） distributed uniformly in the shell via pyrolysis of yolk-shell structured Zn-Co-ZIFs@polydopamine （PDA）. PDA acted as both protection layer and carbon source, which successfully prevented the aggregation of cobalt nanoparticles during high-temperature pyrolysis process. The Co NP and N containing carbon （Co NP/NC） hollow nanospheres were active for both oxygen evolution reaction （OER） and oxygen reduction reaction （ORR）, affording overpotential of 430 mV at 10 mA/cm2 for OER in 1 M KOH and comparable half-wave potential to that of Pt/C （0.80V vs RHE） for ORR in 0.1 M KOH. The superior performance of carbon hollow nanospheres for both OER and ORR was mainly attributed to its small metal nanoparticles, N-doping and hollow nanostructure. The protection and confinement effect that originated from PDA coating strategy could be extended to the synthesis of other hollow structured carbon materials, especially the ones with small metal nanoparticles.
基金financially supported by the National Key R&D Program of China(2019YFC1605002)the National Natural Science Foundation of China(31871735)Xinmiao Talent Project of Zhejiang Province(2019R408063)。
文摘Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.
基金financially supported by the National Natural Science Foundation of China(82101069,82102537,82160411,82002278)the Natural Science Foundation of Chongqing Science and Technology Commission(CSTC2021JCYJ-MSXMX0170,CSTB2022BSXM-JCX0039)+2 种基金the First Affiliated Hospital of Chongqing Medical University Cultivating Fund(PYJJ2021-02)the Beijing Municipal Science&Technology Commission(Z221100007422130)the Youth Incubation Program of Medical Science and Technology of PLA(21QNPY116).
文摘Background:Treatment of methicillin-resistant Staphylococcus aureus(MRSA)biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium(Ti)implants.There is a need to explore more effective approaches for the treatment of MRSA biofilm infections.Methods:Herein,an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles(PDA),nitric oxide(NO)release donor sodium nitroprusside(SNP)and osteogenic growth peptide(OGP)onto Ti implants,denoted as Ti-PDA@SNP-OGP.The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy,X-ray photoelectron spectroscope,water contact angle,photothermal property and NO release behavior.The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2′,7′-dichlorofluorescein diacetate probe,1-N-phenylnaphthylamine assay,adenosine triphosphate intensity,O-nitrophenyl-β-D-galactopyranoside hydrolysis activity,bicinchoninic acid leakage.Fluorescence staining,assays for alkaline phosphatase activity,collagen secretion and extracellular matrix mineralization,quantitative real‑time reverse transcription‑polymerase chain reaction,and enzyme-linked immunosorbent assay(ELISA)were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells(MSCs),RAW264.7 cells and their co-culture system.Giemsa staining,ELISA,micro-CT,hematoxylin and eosin,Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms,inhibition of inflammatory response,and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo.Results:Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light(NIR)irradiation,and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species(ROS)-mediated oxidative stress,destroying bacterial membrane integrity and causing leakage of intracellular components(P<0.01).In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs,but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype(P<0.05 or P<0.01).The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways(P<0.01).In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model(P<0.01).Conclusions:Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.
文摘Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.
基金FAPESP,Brazil(#2023/10027-5,#2014/50945-4,#2020/15230-5,and#2021/000675-4)CNPq,Brazil(#465571/2014-0,#303269/2021-9,and#307837/2014-9)+6 种基金Instituto Serrapilheira(grant number Serra-2211-41925)FAPEMIG,Brazil(#PPM-00831-15)for support of this workCNPq,Brazil(#105944/2022-0)and PROPEUNESP(13/2022)FAPESP(#2019/00463-7,#2018/22845-6,and#2021/08007-0,respectively)for scholarshipsthe National Institute for Alternative Technologies of Detection,Toxicological Evaluation and Removal of Micropollutants and Radioactives(INCT-DATREM)the support of the Research Centre for Greenhouse Gas Innovation(RCGI),hosted by the University of Sao Paulo(USP)and sponsored by FAPESP and Shell Brasilthe strategic support given by ANP,Brazil(Brazilian National Oil,Natural Gas,and Biofuels Agency)through the R&D levy regulation。
文摘This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to itsπ-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au40%electrode,with Faradaic efficiencies of 47.4%(110.5μM cm^(-2))and 27.8%(50.4μM cm^(-2))for methanol and methane,respectively.The performance of the photoelectrodes was shown to be Cu_(2)O facet-dependent,with cubic structures leading to greater conversion of CO_(2)to methanol(43%)and methane(27%),compared to the octahedral morphology,while a higher percentage of metallic gold on the nanostructured Cu_(2)O surface was mainly important for CH4production.Density functional theory(DFT)calculations supported these findings,attributing the superior photoelectrocatalytic performance of the TNT@PDA/Nc/Au40%electrode for CH4generation to the formation of an OCH3intermediate bonded to Au atoms.Studies using isotope-labeling and analysis by gas chromatograph-mass(GC-MS)demonstrated that13CO_(2)was the source for photoelectrocatalytic generation of13CH3OH and13CH313CH2OH.
基金the support of the instrument and equipment fund of the Key Laboratory of Special Energy,Ministry of Education,Nanjing University of Science and Technology,China.
文摘The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.
基金supported by National Natural Science Foundation of China(Grant Nos.U2130207,21875232,12372342)Foundation of President of China Academy of Engineering Physics(Grant Nos.YZJJZQ2023008,YZJJZQ2022006)the Foundation of China Academy of Engineering Physics(Grant Nos.CX20210015,CX20210027)。
文摘The practical application of energetic materials, particularly 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20), is frequently impeded by phase transition challenges. In this study, we propose a novel strategy to enhance the stability of CL-20 by employing a thermo-sensitive polymer,poly(N-isopropylacrylamide)(PNIPAM), to modulate its phase transitions. Our approach involves the use of an in-situ polymerized polydopamine(PDA) shell as a platform for surface grafting through atom transfer radical polymerization, yielding a core-shell structured CL-20@PDA-PNIPAM. Through comprehensive characterization, the successful grafting of PNIPAM is confirmed, significantly enhanced the phase stability of CL-20. Notably, our core-shell structure exhibits a 13℃ increase in phase transition temperature compared to raw CL-20, thereby delaying the ε→a phase transition by over 80 min under combined thermal and solvent conditions. The enhanced stability is attributed to the hydrophobic nature of PNIPAM above its low critical solution temperature in water, which effectively shields the CL-20 crystal. These findings provide new insights into enhancing the stability and safety of energetic materials in complex environments, highlighting the potential of our molecular switch mechanism.
基金supported by the National Natural Science Foundation of China(21875155,51675275,21703185 and 21473119)Q.B.Z.acknowledges the Leading Project Foundation of Science Department of Fujian Province(2018H0034)Shenzhen Science and Technology Planning Project(JCYJ20170818153427106).
文摘The development of high-sulfur-loading Li-S batteries is a key prerequisite for their commercial applications.This requires to surmount the huge polarization,severe polysulfide shuttling and drastic volume change caused by electrode thickening.High-strength polar binders are ideal for constructing robust and long-life high-loading sulfur cathodes but show very weak interfacial interaction with non-polar sulfur materials.To address this issue,this work devises a highly integrated sulfur@polydopamine/highstrength binder composite cathodes,targeting long-lasting and high-sulfur-loading Li-S batteries.The super-adhesion polydopamine(PD)can form a uniform nano-coating over the graphene/sulfur(G-S)surface and provide strong affinity to the cross-linked polyacrylamide(c-PAM)binder,thus tightly integrating sulfur with the binder network and greatly boosting the overall mechanical strength/conductivity of the electrode.Moreover,the PD coating and c-PAM binder rich in polar groups can form two effective blockades against the effusion of soluble polysulfides.As such,the 4.5 mg cm−2 sulfur-loaded G-S@PD-c-PAM cathode achieves a capacity of 480 mAh g−1 after 300 cycles at 1 C,while maintaining a capacity of 396 mAh g−1 after 50 cycles at 0.2 C when the sulfur loading rises to 9.1 mg cm−2.This work provides a system-wide concept for constructing high-loading sulfur cathodes through integrated structural design.
文摘Three-dimensional(3D)micro-jet printing is a droplet deposition technique based on liquid-phase materials.To improve the deposition density and performance of energetic films with micro/nanoscale on an energetic chip,polydopamine(PDA)was utilized as a linker bridge to induce the in-situ self-assembly of CL-20-based energetic film via 3D micro-jet printing.The self-assembly was extensively characterized by confocal laser scanning microscopy(CLSM),SEM,power-XRD,XPS,and DSC.The performance of the self-assembled film was verified by the mechanical properties and detonation properties,and a possible self-assembly mechanism in the layer-by-layer micro-jet printing process was proposed.The results indicated PDA-induced self-assembly enhanced the physical entanglement between the binders and energetic crystal,reduced the porosity from 15.87%to 11.28%,and improved the elastic modulus and the detonation performance of the CL-20-based energetic film.This work proposes a novel and promising energetic film design and fabrication strategy to enhance the interaction between the energetic composite layers in the micro-jet printing process.
基金MA and LS are grateful to the Rowe Family Endowment Fund,and QH acknowledges Tang Fellowship.The financial support from the U.S.National Science Foundation(NSF)with the award number CMMI-1660572 is acknowledged.Further,the discussion of TEM images with Dr.Satyanarayana Emani is appreciated.The use of the Center for Nanoscale Materials,an Office of Science user facility,was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357.
文摘Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,followed by carbonization of polydopamine(PODA)to form a carbon shell,and finally partial etching of the nanostructured Si core by NaOH solution at elevated temperatures.In particular,the effects of ball milling time and NaOH etching temperature on the electrochemical properties of Si/Gr@void@C are investigated.Increasing the ball milling time results in the improved specific capacity of Si-based anodes.Carbon coating further enhances the specific capacity and capacity retention over charge/discharge cycles.The best cycle stability is achieved after partial etching of the Si core inside Si/Gr@void@C particles at either 70 or 80C,leading to little or no capacity decay over 130 cycles.However,it is found that both carbon coating and NaOH etching processes cause some surface oxidation of the nanostructured Si particles derived from high-energy ball milling.The surface oxidation of the nanostructured Si results in decreases in specific capacity and should be minimized in future studies.The mechanistic understanding developed in this study paves the way to further improve the electrochemical performance of Si/Gr@void@C nanocomposites in future.
基金supported by the National Natural Science Foundation of China(Grant No.22005275).
文摘Surface engineering plays a crucial role in improving the performance of high energy materials,and polydopamine(PDA)is widely used in the field of energetic materials for surface modification and functionalization.In order to obtain high-quality HMX@PDA-based PBX explosives with high sphericity and a narrow particle size distribution,composite microspheres were prepared using co-axial droplet microfluidic technology.The formation mechanism,thermal behavior,mechanical sensitivity,electrostatic spark sensitivity,compressive strength,and combustion performance of the microspheres were investigated.The results show that PDA can effectively enhance the interfacial interaction between the explosive particles and the binder under the synergistic effect of chemical bonds and the physical"mechanical interlocking"structure.Interface reinforcement causes the thermal decomposition temperature of the sample microspheres to move to a higher temperature,with the sensitivity to impact,friction,and electrostatic sparks(for S-1)increasing by 12.5%,31.3%,and 81.5%respectively,and the compressive strength also increased by 30.7%,effectively enhancing the safety performance of the microspheres.Therefore,this study provides an effective and universal strategy for preparing high-quality functional explosives,and also provides some reference for the safe use of energetic materials in practical applications.
