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Ultrafine ordered L1_(2)-Pt-Co-Mn ternary intermetallic nanoparticles as high-performance oxygen-reduction electrocatalysts for practical fuel cells
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作者 Enping Wang Liuxuan Luo +12 位作者 Yong Feng Aiming Wu Huiyuan Li Xiashuang Luo Yangge Guo Zehao Tan Fengjuan Zhu Xiaohui Yan Qi Kang Zechao Zhuang Daihui Yang Shuiyun Shen junliang zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第6期157-165,I0005,共10页
The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction... The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts. 展开更多
关键词 Platinum Cobalt Manganese Oxygen reduction reaction Ordered intermetallic L1_(2)atomic structure Proton-exchange membrane fuel cell
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Potential-dependent insights into the origin of high ammonia yield rate on copper surface via nitrate reduction:A computational and experimental study
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作者 Yangge Guo Nannan Sun +5 位作者 Liuxuan Luo Xiaojing Cheng Xueying Chen Xiaohui Yan Shuiyun Shen junliang zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第9期272-281,共10页
Focusing on revealing the origin of high ammonia yield rate on Cu via nitrate reduction(NO3RR),we herein applied constant potential method via grand-canonical density functional theory(GC-DFT)with implicit continuum s... Focusing on revealing the origin of high ammonia yield rate on Cu via nitrate reduction(NO3RR),we herein applied constant potential method via grand-canonical density functional theory(GC-DFT)with implicit continuum solvation model to predict the reaction energetics of NO3RR on pure copper surface in alkaline media.The potential-dependent mechanism on the most prevailing Cu(111)and the minor(100)and(110)facets were established,in consideration of NO_(2)_(−),NO,NH_(3),NH_(2)OH,N_(2),and N_(2)O as the main products.The computational results show that the major Cu(111)is the ideal surface to produce ammonia with the highest onset potential at 0.06 V(until−0.37 V)and the highest optimal potential at−0.31 V for ammonia production without kinetic obstacles in activation energies at critical steps.For other minor facets,the secondary Cu(100)shows activity to ammonia from−0.03 to−0.54 V with the ideal potential at−0.50 V,which requires larger overpotential to overcome kinetic activation energy barriers.The least Cu(110)possesses the longest potential range for ammonia yield from−0.27 to−1.12 V due to the higher adsorption coverage of nitrate,but also with higher tendency to generate di-nitrogen species.Experimental evaluations on commercial Cu/C electrocatalyst validated the accuracy of our proposed mechanism.The most influential(111)surface with highest percentage in electrocatalyst determined the trend of ammonia production.In specific,the onset potential of ammonia production at 0.1 V and emergence of yield rate peak at−0.3 V in experiments precisely located in the predicted potentials on Cu(111).Four critical factors for the high ammonia yield and selectivity on Cu surface via NO3RR are summarized,including high NO3RR activity towards ammonia on the dominant Cu(111)facet,more possibilities to produce ammonia along different pathways on each facet,excellent ability for HER inhibition and suitable surface size to suppress di-nitrogen species formation at high nitrate coverage.Overall,our work provides comprehensive potential-dependent insights into the reaction details of NO3RR to ammonia,which can serve as references for the future development of NO3RR electrocatalysts,achieving higher activity and selectivity by maximizing these characteristics of copper-based materials. 展开更多
关键词 Nitrate reduction to ammonia Copper surface Density functional theory Constant electrode potential method Experimental validation
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MoS2-rGO hybrid architecture as durable support for cathode catalyst in proton exchange membrane fuel cells 被引量:5
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作者 Muhammad Tuoqeer Anwar Xiaohui Yan +6 位作者 Muhammad Rehman Asghar Naveed Husnain Shuiyun Shen Liuxuan Luo Xiaojing Cheng Guanghua Wei junliang zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第8期1160-1167,共8页
Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting th... Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material. 展开更多
关键词 Fuel cell Hybrid catalyst support Carbon corrosion Supported catalyst Pt-based electrocatalyst
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In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells(PEMFCs) 被引量:2
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作者 Sheng Sui Xiaolong Zhuo +4 位作者 Kaihua Su Xianyong Yao junliang zhang Shangfeng Du Kevin Kendall 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第3期477-483,共7页
An extensive study has been conducted on the proton exchange membrane fuel cells (PEMFCs) with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the ... An extensive study has been conducted on the proton exchange membrane fuel cells (PEMFCs) with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode (GCE) to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic (IV) acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm (diameter) x l0 nm (length) by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry (CV) and scanning electron microscope (SEM) as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants (oxygen or hydrogen). 展开更多
关键词 PLATINUM catalyst layer carbon powder layer proton exchange membrane fuel cells
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First-principles study of catalytic activity of W-doped cobalt phosphide toward the hydrogen evolution reaction 被引量:2
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作者 Cehuang Fu Xiaohui Yan +4 位作者 Lijun Yang Shuiyun Shen Liuxuan Luo Guanghua Wei junliang zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第11期1698-1705,共8页
In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co at... In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface. 展开更多
关键词 Hydrogen Evolution Reaction Density functional theory COP DOPING
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Study on the Supply Efficiency of Rural Public Service in China Based on Three-stage DEA Model 被引量:3
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作者 Zongbing DENG Chaoying WU +1 位作者 junliang zhang Ju WANG 《Asian Agricultural Research》 2014年第1期6-13,共8页
Improving the supply efficiency of rural public service is an important way to solve the severe shortage of rural public service. In this article,we use three-stage DEA model to carry out empirical research of the sup... Improving the supply efficiency of rural public service is an important way to solve the severe shortage of rural public service. In this article,we use three-stage DEA model to carry out empirical research of the supply efficiency of rural public service in 31 provinces and regions of China. The results show that if without control over exogenous environment variables and random brunt,the classic DEA method will overestimate the rural public service efficiency; after controlling the impact of the external environmental factors,the mean of supply efficiency of rural public service in 31 provinces and regions of China is 0. 697; the improved rural per capita income,population density,population size and the educational level of residents,is a significantly favorable factor for enhancing the supply efficiency of rural public service,while the increase in the proportion of fiscal spending on rural public service to GDP plays no significant role in improving the rural public service efficiency; according to their efficiency type,the provinces and regions should adopt some measures,such as improving the management level or expanding the supply scale,to improve the supply efficiency. 展开更多
关键词 RURAL PUBLIC SERVICE Supply EFFICIENCY Influencing
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Electrodeposited PtNi nanoparticles towards oxygen reduction reaction:A study on nucleation and growth mechanism 被引量:1
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作者 Lutian Zhao Yangge Guo +4 位作者 Cehuang Fu Liuxuan Luo Guanghua Wei Shuiyun Shen junliang zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第11期2068-2077,共10页
In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbo... In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbon supported Pt-Ni alloy electrocatalysts were synthesized under different applied electrode potentials.Among all as-obtained samples,the Pt-Ni/C electrocatalyst deposited at-1.73 V exhibits the optimal specific activity up to 1.850 mA cm^(-2)at 0.9 V vs.RHE,which is 6.85 times higher than that of the commercial Pt/C.Comprehensive physiochemical characterizations and computational evaluations via density functional theory were conducted to unveil the nucleation and growth mechanism of PtNi alloy formation.Compared to the aqueous solution,DMF solvent molecule must not be neglected in avoiding particle agglomeration and synthesis of monodispersed nanoparticles.During the alloy co-deposition process,Ni sites produced through the reduction of Ni(Ⅱ)precursor not only facilitates Pt-Ni alloy crystal nucleation but also in favor of further Pt reduction on the Ni-inserted Pt surface.As for the deposition potential,it adjusts the final particle size.This work provides a hopeful extended Pt-based catalyst layer production strategy for proton exchange membrane fuel cells and a new idea for the nucleation and growth mechanism exploration for electrodeposited Pt alloy. 展开更多
关键词 ELECTRODEPOSITION PtNi alloy nanoparticles Oxygen reduction reaction Nucleation and growth mechanism Density functional theory
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Factors Influencing the Supply Efficiency of Basic Public Service at County Level 被引量:1
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作者 Zongbing DENG junliang zhang +1 位作者 Yonggang FENG Ju WANG 《Asian Agricultural Research》 2013年第9期53-59,共7页
In this paper,we use DEA-Tobit model to conduct empirical study on the governmental supply efficiency of public service in Chongqing's 38 counties and the influencing factors during the period 2008-2011.The result... In this paper,we use DEA-Tobit model to conduct empirical study on the governmental supply efficiency of public service in Chongqing's 38 counties and the influencing factors during the period 2008-2011.The results show that the supply efficiency of basic public service at county level is generally low,and there is significant regional differences and strong volatility;per capita GDP,population density and population size,and level of education of the residents,are significantly correlated with the supply efficiency of basic public service at county level,but traffic density,urbanization level,and the proportion of government spending on public service to total fiscal expenditure,have no significant effects on the efficiency of basic public service at county level.Based on this,we propose some policy recommendations for enhancing the level of local economic development and the level of education,and reasonably guiding the residents'agglomeration. 展开更多
关键词 PUBLIC SERVICE Supply EFFICIENCY Influencing facto
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Designing an automated FAQ answering system for farmers based on hybrid strategies 被引量:1
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作者 junliang zhang Xuefang ZHU Guang ZHU 《Chinese Journal of Library and Information Science》 2012年第4期21-36,共16页
Purpose: The purpose of this study is to develop an automated frequently asked question(FAQ) answering system for farmers. This paper presents an approach for calculating the similarity between Chinese sentences based... Purpose: The purpose of this study is to develop an automated frequently asked question(FAQ) answering system for farmers. This paper presents an approach for calculating the similarity between Chinese sentences based on hybrid strategies.Design/methodology/approach: We analyzed the factors influencing the successful matching between a user's question and a question-answer(QA) pair in the FAQ database. Our approach is based on a combination of multiple factors. Experiments were conducted to test the performance of our method.Findings: Experiments show that this proposed method has higher accuracy. Compared with similarity calculation based on TF-IDF,the sentence surface forms and the semantic relations,the proposed method based on hybrid strategies has a superior performance in precision,recall and F-measure value.Research limitations: The FAQ answering system is only capable of meeting users' demand for text retrieval at present. In the future,the system needs to be improved to meet users' demand for retrieving images and videos.Practical implications: This FAQ answering system will help farmers utilize agricultural information resources more efficiently.Originality/value: We design the algorithms for calculating similarity of Chinese sentences based on hybrid strategies,which integrate the question surface similarity,the question semantic similarity and the question-answer similarity based on latent semantic analysis(LSA) to find answers to a user's question. 展开更多
关键词 Frequently asked question(FAQ)answering system Sentence surface similarity Semantic similarity Latent semantic analysis(LSA) Similarity computation based on hybrid strategies FAQ answering system for farmers
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Modification and sequential treatment of EU-1 zeolite in mild alkali and alkaline-acid conditions
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作者 Xiaofeng Li Xiaotao Sun +4 位作者 Yanting zhang junliang zhang Pengchao Ren Xiaozhen Liu Tao Dou 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第12期1728-1734,共7页
EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron micros... EU-1 zeolites were sequentially treated with low-concentration sodium carbonate(Na_2CO_3) and hydrochloric acid(HCl) solutions.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),N_2 adsorption/desorption,temperature programmed desorption of NH_3(NH_3-TPD),solid state^(27)A1 nuclear magnetic resonance(^(27)A1 NMR),and the catalytic performances of the treated samples were tested in the xylene isomerization reaction.The results showed that the external surface area and mesoporous volume of the sample sequentially treated with 0.05 mol·L^(-1) Na_2CO_3 and 0.1 mol·L^(-1) HCl solutions reached73.9 m^2·g^(-1) and 0.162 cm^3·g^(-1),respectively.The catalytic performances of EU-1 zeolites were significantly improved,that the activity of the probe reaction increased from 23.03%to 23.61%and the selectivity increased from85.09%to 87.14%compared with those of parent sample.Furthermore,it was found that only amorphous silica and alumina species was dissolved during the post-treatment process,but the framework structure and the acidic properties of EU-1 zeolite remained intact. 展开更多
关键词 EU-1 zeolite Mesoporous Catalysis
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Palladium/Xu-Phos Catalyzed Enantioselective Intramolecular Heck Reaction of Unactivated Alkenes
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作者 Lujia Zhou Longling Ma +2 位作者 Bing Xu Zhan-Ming zhang junliang zhang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2024年第20期2466-2470,共5页
A highly enantioselective palladium-catalyzed intramolecular Heck reaction of unactivated alkenes is developed,which provides a powerful route to access a broad range of chiral 3,3-disubstituted-2,3-dihydrobenzofurans... A highly enantioselective palladium-catalyzed intramolecular Heck reaction of unactivated alkenes is developed,which provides a powerful route to access a broad range of chiral 3,3-disubstituted-2,3-dihydrobenzofurans bearing all-carbon quaternary stereocenter of interest in pharmaceutical research.Its salient features include high yield,excellent chemo-and enantioselectivity,mild conditions,a broad substrate scope as well as versatile transformations of the product. 展开更多
关键词 PALLADIUM HECK 2 3-Dihydrobenzofuran Asymmetric catalysis Quaternary stereocenter ENANTIOSELECTIVE P ligands ALKENES
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Nickel-Catalyzed Regio-and Stereoselective Defluorinative Arylation of gem-Difluorinated Cyclopropanes
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作者 Shutao Qi Yunkai Hua +2 位作者 Liangkai Pan Junfeng Yang junliang zhang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2024年第8期823-828,共6页
Comprehensive Summary,Herein,we report nickel-catalyzed cross-coupling of gem-difluorinated cyclopropanes with boronic acids,providing the corresponding arylated 2-fluoroallylic scaffolds.This approach used commercial... Comprehensive Summary,Herein,we report nickel-catalyzed cross-coupling of gem-difluorinated cyclopropanes with boronic acids,providing the corresponding arylated 2-fluoroallylic scaffolds.This approach used commercially available phosphine ligand Xantphos to obtain monofluorinated alkenes with high regioselectivity and Z-stereoselectivity.Mechanistic studies proposed a Ni(II)-fluoroallyl pathway and excluded the radical pathway. 展开更多
关键词 Nickel Monofluoroolefin CYCLOPROPANE Regioselectivity STEREOSELECTIVITY C-C coupling Cross-coupling Synthetic methods
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Improved cyclic stability of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) cathode enabled by a novel CEI forming additive
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作者 Zulipiya SHADIKE Yiming CHEN +3 位作者 Lin LIU Xinyin CAI Shuiyun SHEN junliang zhang 《Frontiers in Energy》 SCIE EI CSCD 2024年第4期535-544,共10页
The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode mat... The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode materials.Electrolyte optimization is an effective approach to suppress such an adverse side reaction,thereby enhancing the electrochemical properties.Herein,a novel boron-based film forming additive,tris(2,2,2-trifluoroethyl)borate(TTFEB),has been introduced to regulate the interphasial chemistry of LiNi0.8Mn0.1Co0.1O2(NMC811)cathode to improve its long-term cyclability and rate properties.The results of multi-model diagnostic study reveal that formation lithium fluoride(LiF)-rich and boron(B)containing cathode electrolyte interphase(CEI)not only stabilizes cathode surface,but also prevents electrolyte decomposition.Moreover,homogenously distributed B containing species serves as a skeleton to form more uniform and denser CEI,reducing the interphasial resistance.Remarkably,the Li/NMC811 cell with the TTFEB additive delivers an exceptional cycling stability with a high-capacity retention of 72.8%after 350 electrochemical cycles at a 1 C current rate,which is significantly higher than that of the cell cycled in the conventional electrolyte(59.7%).These findings provide a feasible pathway for improving the electrochemical performance of Ni-rich NMCs cathode by regulating the interphasial chemistry. 展开更多
关键词 NMC811 cathode electrolyte interphase film forming additives cyclic stability
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Polymer-supported chiral palladium-based complexes as efficient heterogeneous catalysts for asymmetric reductive Heck reaction
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作者 Hui zhang Bing Xu +2 位作者 Liejin Zhou Zhan-Ming zhang junliang zhang 《Green Synthesis and Catalysis》 2024年第2期102-107,共6页
Heterogeneous asymmetric catalysis is an important strategy for the industrial production of chiral compounds.Herein,we reported a polymer-bound Xu-Phos-derived palladium catalyst that shows good performance in hetero... Heterogeneous asymmetric catalysis is an important strategy for the industrial production of chiral compounds.Herein,we reported a polymer-bound Xu-Phos-derived palladium catalyst that shows good performance in heterogeneous asymmetric reductive Heck reaction of allyl aryl ethers.This heterogeneous catalyst was easily prepared by efficient immobilization of the sulfonamide phosphine ligand(Xu-Phos)in the cross-linked polystyrene via copolymerization,and exhibits similar catalytic activity and enantioselectivity to that of the homogeneous catalyst.Moreover,the heterogeneous catalyst system is proved to be easily recovered and reused several times without losing catalytic activity obviously. 展开更多
关键词 Heterogeneous catalysis RECOVERABILITY Palladium HYDROARYLATION Asymmetric catalysis
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Rhodium/Ming-Phos-catalyzed asymmetric annulation reaction of silacyclobutanes with terminal alkynes
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作者 Yue Sun Kaida Zhou +2 位作者 Chun Ma Zhiming Li junliang zhang 《Green Synthesis and Catalysis》 2024年第3期205-210,共6页
Asymmetric ring-expansion reactions of silacyclobutanes(SCBs)with alkynes have evolved as one of the powerful protocols for the construction of silicon-stereogenic compounds.However,the achievement of highly enantiose... Asymmetric ring-expansion reactions of silacyclobutanes(SCBs)with alkynes have evolved as one of the powerful protocols for the construction of silicon-stereogenic compounds.However,the achievement of highly enantioselective annulation of SCBs with terminal alkynes remains a challenge.Herein,we report a rhodium-catalyzed asymmetric annulation reaction of SCBs with terminal alkynes,which relies on the newly identified chiral sulfinamide phosphine ligand Ming-Phos.This catalytic system exhibits unique effects under mild conditions,leading to the direct synthesis of structurally diverse chiral silacycles in moderate to good yields with high enantioselectivities(up to 95%ee). 展开更多
关键词 Rhodium-catalysis Asymmetric annulation reaction Silicon-stereogenic Silacyclobutanes Terminal alkynes
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PBO fibers/fluorine-containing liquid crystal compound modified cyanate ester wave-transparent laminated composites with excellent mechanical and flame retardance properties 被引量:9
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作者 Zheng Liu Xiaoli Fan +4 位作者 junliang zhang Lixin Chen Yusheng Tang Jie Kong Junwei Gu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第21期16-29,共14页
Bisphenol A dicyanate ester resins modified by fluorine-containing liquid crystal compound(LCFE)are applied as polymer matrix(LCFE-BADCy),poly(p-phenylene-2,6-benzobisoxazole)(PBO)fibers as rein-forcements,and fluorin... Bisphenol A dicyanate ester resins modified by fluorine-containing liquid crystal compound(LCFE)are applied as polymer matrix(LCFE-BADCy),poly(p-phenylene-2,6-benzobisoxazole)(PBO)fibers as rein-forcements,and fluorine/adamantane PBO precursor(pre FABPBO)as interfacial compatibilizer to prepare the corresponding PBO fibers/FABPBO/LCFE-BADCy wave-transparent laminated composites.LCFE could improve the order degree of BADCy cured network,in favor of enhancing the wave-transparent perfor-mance,mechanical properties,and intrinsic thermal conductivity.The dielectric constant and dielectric loss of PBO fibers/FABPBO/LCFE-BADCy composites are highly temperature(25–200℃)and frequency(10^(4)–10^(7) Hz and 8.2–12.4 GHz)stable with the value of 2.49 and 0.003 under 10^(6) Hz at 25℃,and the corresponding wave transmission efficiency is 95.0%,higher than that of 92.5%for PBO fibers/BADCy com-posites.The interlamellar shear strength and flexural strength are respectively 50.7 MPa and 682.5 MPa,38.1%and 16.2%higher than those of PBO fibers/BADCy composites.Besides,the volume resistivity,breakdown voltage,heat resistance index,glass transition temperature,flame retardant grade,and ul-timate oxygen index of PBO fibers/FABPBO/LCFE-BADCy composites are respectively 5.3×10^(15)Ωcm,29.75 kV/mm,217.2℃,245.7℃,V-1 grade,and 33.6%,expected to be performed as a new generation of“lightweight/loading/wave-transparent”electromagnetic window materials in advanced military weapons and civil communication base station. 展开更多
关键词 Bisphenol A dicyanate ester(BADCy)resins Fluorine-containing liquid crystal compound Poly(p-phenylene-2 6-benzobisoxazole) (PBO)fibers Fluorine/adamantane PBO precursor Wave-transparent laminated composites
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Branched Fluorine/Adamantane Interfacial Compatibilizer for PBO Fibers/Cyanate Ester Wave-Transparent Laminated Composites 被引量:6
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作者 Zheng Liu Xiaoli Fan +5 位作者 Muyi Han Hao Li junliang zhang Lixin Chen Qiju Zhu Junwei Gu 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2023年第8期939-950,共12页
Comprehensive Summary Branched fluorine/adamantane PBO precursor(preFABPBO),synthesized via random co-condensation between 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoro propane,1,3-adamantanedicarbonyl dichloride,and tri... Comprehensive Summary Branched fluorine/adamantane PBO precursor(preFABPBO),synthesized via random co-condensation between 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoro propane,1,3-adamantanedicarbonyl dichloride,and trimesoyl chloride,is performed as interfacial compatibilizer,bisphenol A dicyanate ester(BADCy)resin as polymer matrix,and poly(p-phenylene-2,6-benzobisoxazole)(PBO)fibers as reinforcements to prepare PBO fibers/FABPBO-BADCy wave-transparent laminated composites by high temperature molding.The mechanical properties,wave-transparent performances,and heat resistances of PBO fibers/BADCy composites are simultaneously improved by the addition of preFABPBO.The interlaminar shear strength(ILSS)and flexural strength of PBO fibers/FABPBO-BADCy composites are 48.9 and 665.3 MPa,respectively,increased by 33.2%and 13.3%compared to those of PBO fibers/BADCy composites(36.7 and 587.4 MPa).The dielectric constant and dielectric loss values at 106 Hz are 2.53 and 0.003,respectively,lower than those of PBO fibers/BADCy composites(3.06 and 0.006),and the corresponding wave transmission efficiency is 94.8%,which also presents excellent stability over the wide temperature(25-200℃)and frequency range(103-107 Hz and 8.2-12.4 GHz).Meanwhile,the heat resistance index and glass transition temperature are 229.9℃and 247.5℃,also better than those of PBO fibers/BADCy composites(229.6℃and 247.1℃). 展开更多
关键词 Polymers Interface Materials science Mechanical properties Wave-transparent laminated composites
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A perspective on influences of cathode material degradation on oxygen transport resistance in low Pt PEMFC 被引量:3
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作者 Huiyuan Li Xiaojing Cheng +2 位作者 Xiaohui Yan Shuiyun Shen junliang zhang 《Nano Research》 SCIE EI CSCD 2023年第1期377-390,共14页
A large-scale industrial application of proton exchange membrane fuel cells(PEMFCs)greatly depends on both substantial cost reduction and continuous durability enhancement.However,compared to effects of material degra... A large-scale industrial application of proton exchange membrane fuel cells(PEMFCs)greatly depends on both substantial cost reduction and continuous durability enhancement.However,compared to effects of material degradation on apparent activity loss,little attention has been paid to influences on the phenomena of mass transport.In this review,influences of the degradation of key materials in membrane electrode assemblies(MEAs)on oxygen transport resistance in both cathode catalyst layers(CCLs)and gas diffusion layers(GDLs)are comprehensively explored,including carbon support,electrocatalyst,ionomer in CCLs as well as carbon material and hydrophobic polytetrafluoroethylene(PTFE)in GDLs.It is analyzed that carbon corrosion in CCLs will result in pore structure destruction and impact ionomer distribution,thus affecting both the bulk and local oxygen transport behavior.Considering the catalyst degradation,an eventual decrease in electrochemical active surface area(ECSA)definitely increases the local oxygen transport resistance since a decrease in active sites will lead to a longer oxygen transport path.It is also noted that problems concerning oxygen transport caused by the degradation of ionomer chemical structure in CCLs should not be ignored.Both cation contamination and chemical decomposition will change the structure of ionomer,thus worsening the local oxygen transport.Finally,it is found that the loss of carbon and PTFE in GDLs lead to a higher hydrophilicity,which is related to an occurrence of water flooding and increase in the oxygen transport resistance. 展开更多
关键词 proton exchange membrane fuel cells(PEMFC) oxygen transport resistance DEGRADATION cathode catalyst layer gas diffusion layer
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Block copolymer functionalized quartz fibers/cyanate ester wave-transparent laminated composites 被引量:1
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作者 Jiani zhang Zheng Liu +3 位作者 Muyi Han junliang zhang Yusheng Tang Junwei Gu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第8期189-197,共9页
A block copolymer of PDMS-b-PGMA is synthesized by polymerizing glycidyl methacrylate(GMA)via reversible addition-fragmentation chain transfer(RAFT)polymerization applying a polydimethylsiloxane(PDMS)based macro-RAFT ... A block copolymer of PDMS-b-PGMA is synthesized by polymerizing glycidyl methacrylate(GMA)via reversible addition-fragmentation chain transfer(RAFT)polymerization applying a polydimethylsiloxane(PDMS)based macro-RAFT agent,which is then performed to functionalize the quartz fibers(QFs@PDMS-b-PGMA)via a simple coating process.Finally,the QFs@PDMS-b-PGMA/bisphenol A dicyanate ester(BADCy)wave-transparent laminated composites are fabricated by high-temperature molding.Nuclear magnetic resonance(NMR)spectroscopy,Fourier transform infrared(FT-IR)spectroscopy and size ex-clusion chromatography(SEC)demonstrate the successful preparation of PDMS-b-PGMA with expected structure.When the molar mass and coating amount of PDMS-b-PGMA are respectively 8100 g/mol and 2.0 wt.%,QFs@PDMS-b-PGMA/BADCy wave-transparent laminated composites present optimal mechan-ical properties and wave-transparent performance.The interlaminar shear strength(ILSS)and flexural strength are 53.6 and 552.0 MPa,respectively.Meanwhile,the dielectric constant and dielectric loss val-ues are 2.61 and 0.0028 at 1 MHz(wave transmittance of 93.8%),showing good stability at different frequencies(102-106 Hz and 8.4-12.4 GHz)and temperatures(25-250℃). 展开更多
关键词 Bisphenol A dicyanate ester(BADCy)resins Quartz fibers(QFs) Wave-transparent laminated composites Block copolymer
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Half‑Power Prediction and Its Application on the Energy Management Strategy for Fuel Cell City Bus 被引量:1
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作者 Longhai zhang Lina Ning +5 位作者 Xueqing Yang Sheng Zeng Tian Yuan Gaopeng Li Changchun Ke junliang zhang 《Automotive Innovation》 EI CSCD 2023年第1期131-142,共12页
The fuel cell hybrid powertrain is a potential power supply system for fuel cell vehicles.The underlying problem is that the fuel cell vehicles encounter exhaustive hydrogen consumption.To effectively manage hydrogen ... The fuel cell hybrid powertrain is a potential power supply system for fuel cell vehicles.The underlying problem is that the fuel cell vehicles encounter exhaustive hydrogen consumption.To effectively manage hydrogen consumption,the aim is to propose fuel cell city bus power and control system.The underlying idea is to determine the target power of fuel cell through simulation study on fuel cell and battery energy management strategy and road test verifications.A half-power prediction energy management strategy is implemented to predict the target power of the fuel cell in the current time step based on the demand power of the vehicle and the state of charge(SOC)of the battery in the previous time steps.This offers better understanding of the correlation between fuel cell power and vehicle drive cycle for enabling effective power supply management.The research results show that the half-power prediction energy management strategy effectively reduces the hydrogen consumption of the vehicle by 7.1%and the number of battery cycle by 6.0%,compared to the stepped manage-ment strategy of battery SOC.When applied to a 12-m fuel cell city bus—F12,specially designed and manufactured for the Winter Olympic Games in 2022—the fuel economy of 3.7 kg/100 km is achieved in urban road conditions.This study lays a foundation for providing the powertrain configuration and energy management strategy of fuel cell city bus. 展开更多
关键词 Fuel cell city bus Energy management Half-power prediction
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