首页 > 期刊 > 物理化学学报
亮点
少层石墨双炔薄膜的液相范德华外延生长法
李玉良
2019, 35(7): 657-658  doi: 10.3866/PKU.WHXB201809044
[摘要]  (49) [HTML全文] (49) [PDF 569KB] (4)
摘要:
氮磷共掺杂—提升氧还原催化剂毒化分子耐受性(SOx,NOx和POx)
庄林
2019, 35(7): 659-660  doi: 10.3866/PKU.WHXB201809045
[摘要]  (47) [HTML全文] (47) [PDF 1009KB] (2)
摘要:
一种梯度亲锂-憎锂的锂金属负极保护策略
崔屹
2019, 35(7): 661-662  doi: 10.3866/PKU.WHXB201809053
[摘要]  (46) [HTML全文] (46) [PDF 604KB] (2)
摘要:
当期推荐
表面活性剂增强叶酸的光稳定性
刘鸣华
2019, 35(7): 663-664  doi: 10.3866/PKU.WHXB201811042
[摘要]  (36) [HTML全文] (36) [PDF 413KB] (3)
摘要:
锂硒电池正极材料设计
庄林
2019, 35(7): 665-666  doi: 10.3866/PKU.WHXB201812001
[摘要]  (47) [HTML全文] (47) [PDF 280KB] (4)
摘要:
综述
锂硒电池正极材料的研究进展
陈东, 岳昕阳, 李璕琭, 吴晓京, 周永宁
2019, 35(7): 667-683  doi: 10.3866/PKU.WHXB201806062
[摘要]  (52) [HTML全文] (52) [PDF 4989KB] (5)
摘要:
锂硒电池因其高体积比容量(3253 mAh·cm-3),以及硒的高电导率(1 × 10-3 S·m-1)等显著优点,在体积受限的储能系统中具有潜在的应用价值。引起了国内外研究学者的广泛关注。但是,目前锂硒电池的性能还不理想,仍然存在许多科学问题亟待解决,包括多硒化锂的穿梭效应,电解液的适配性,充放电过程中电极体积变化等。近年来,研究工作者针对这些关键科学问题开展了许多研究和探索,锂硒电池已成为储能领域的一个新的研究热点。本文综述了锂硒电池的研究现状,着重介绍了硒-碳复合正极材料的研究进展,论述了锂硒电池的优势及存在的问题,系统分析了硒基正极材料结构和性能之间的关系,总结了锂硒电池的反应机理及其与电解液的相关性,最后展望了锂硒电池的未来发展方向。
胆酸盐参与的自组装及微纳米材料制备
焦建梅, 徐桂英, 辛霞
2019, 35(7): 684-696  doi: 10.3866/PKU.WHXB201806056
[摘要]  (36) [HTML全文] (36) [PDF 3866KB] (2)
摘要:
胆酸盐类物质可看作是一类阴离子型甾族生物表面活性剂,鉴于其特殊的两亲性骨架结构、独特的物理化学性质及其良好的生物相容性和环境友好性,其在溶液中能够参与超分子自组装形成有序聚集结构,且可以作为模板在微纳材料制备领域有着重要应用。本文结合我们课题组的研究工作,综述了近期国内外相关研究,详细介绍了生物小分子氨基酸对胆酸盐聚集行为的影响、胆酸盐参与形成的超分子凝胶及胆酸盐参与构筑的微纳米材料制备等方面的研究进展,以期对胆酸盐参与的自组装及微纳米材料制备领域的研究有更全面更深入的了解,为后续的应用研究提供坚实的基础。
同核铁系双金属络合物及其在均相催化体系中的应用
王露, 孙威, 刘超
2019, 35(7): 697-708  doi: 10.3866/PKU.WHXB201807071
[摘要]  (44) [HTML全文] (44) [PDF 963KB] (4)
摘要:
随着合成化学的不断发展,开发高活性催化剂来活化一些惰性化学键或者惰性分子受到越来越多的关注。双核金属络合物作为一类特殊的催化剂展现出了不同于单核金属催化剂的催化活性。在双核过渡金属催化体系中,因两个金属中心存在协同作用而表现出了独特的催化活性。铁、钴、镍为第四周期第Ⅷ族元素,也称为铁系元素。该类金属廉价易得且参与的催化反应种类繁多,近年来引起了人们的广泛关注。本综述重点介绍了近年来同核双金属铁系络合物的合成及其表征。同时,对相关同核铁、钴以及镍催化剂在均相催化体系中的应用也进行了详细的介绍和总结。
石墨烯基吸附剂的设计及其对水中抗生素的去除
姜哲, 于飞, 马杰
2019, 35(7): 709-724  doi: 10.3866/PKU.WHXB201807051
[摘要]  (43) [HTML全文] (43) [PDF 3174KB] (1)
摘要:
抗生素的大量使用,所带来的环境污染问题受到广泛关注。吸附法因去除效率高、普遍适用性强,呈现出广阔的应用前景,开发新型吸附剂是高效能吸附处理的关键。近年来石墨烯优良的物理和化学性质以及吸附性能,使其成为重要的抗生素吸附剂。由于石墨烯自身的局限性以及对石墨烯吸附剂处理效能和稳定性的要求,基于石墨烯设计开发了多种石墨烯基吸附材料。而目前基于水体中抗生素的石墨烯基复合材料的设计、合成及其吸附作用机制缺乏相关的系统性综述。本文综述了目前水体中抗生素的危害,针对石墨烯基复合吸附材料中,广泛关注的磁性石墨烯吸附剂、聚合物/石墨烯吸附剂、三维石墨烯凝胶和石墨烯/生物炭吸附剂的设计和制备方法进行了总结和概述,并阐述了石墨烯基吸附材料对水体中抗生素的主要吸附作用机制。最后,本文对石墨烯基吸附材料去除水体中抗生素未来的发展方向进行了展望。
论文
桑色素与血清白蛋白相互作用热力学行为
谢文, 何欢, 董家新, 郭清莲, 刘义
2019, 35(7): 725-733  doi: 10.3866/PKU.WHXB201810019
[摘要]  (39) [HTML全文] (39) [PDF 1953KB] (4)
摘要:
利用荧光光谱、紫外-可见吸收光谱、圆二色谱、分子模拟等方法,在近似生理条件下,以牛血清白蛋白(BSA)为模式蛋白质,研究了桑色素(Morin)和血清白蛋白相互作用的热力学行为及其特征。荧光光谱结果表明:Morin能有效猝灭BSA的内源荧光,猝灭机制为静态猝灭;通过van’t Hoff方程,获取了BSA与Morin结合的热力学参数(ΔHƟ、ΔSƟ、ΔGƟ等),发现Morin与BSA两者之间的相互作用是一个吉布斯自由能降低的自发过程,且氢键和范德华力是二者结合的驱动力。通过分子模拟方法,发现Morin结合在BSA分子亚结构域ⅢA的疏水腔内位点Ⅱ,荧光共振能量转移结果表明Morin和与BSA的两个色氨酸残基的平均距离为3.09 nm。圆二色谱结果表明Morin分子的结合会引起BSA分子α-螺旋含量降低。
基于共价有机框架复合材料的锂硒电池应用
李路路, 姚路, 段力
2019, 35(7): 734-739  doi: 10.3866/PKU.WHXB201806063
[摘要]  (39) [HTML全文] (39) [PDF 1000KB] (4)
摘要:
本文利用溶剂热反应方法,在多壁碳纳米管(MWCNTs)管壁上生长了共价有机框架(TpPa-COF)材料,并将这种核壳多壁碳纳米管/共价有机框架纳米复合材料(MWCNTs@TpPa-COF)成功应用在锂硒电池上。利用场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FT-IR)等手段对材料结构进行表征,结果表明多壁碳纳米管和共价有机框架材料成功复合。电化学测试结果表明,该材料在电流密度3C (1C = 675 mA∙g−1)下的质量比容量为463.5 mAh∙g−1,500次循环后能保持99%的库仑效率,表明锂硒电池具有优异的循环稳定性和较长的循环寿命。
Ru修饰Pd二十四面体纳米晶的合成及其甲醇电催化氧化性能
郭锦成, 林燕芬, 田娜, 孙世刚
2019, 35(7): 749-754  doi: 10.3866/PKU.WHXB201810051
[摘要]  (44) [HTML全文] (44) [PDF 962KB] (4)
摘要:
表面结构控制和表面异种金属修饰是调控催化剂反应性的重要方法。因此,我们结合高指数晶面结构的高反应性与表面修饰异种金属,合成具有{730}高指数晶面的钯二十四面体纳米晶,并通过循环伏安扫描电沉积法得到Ru修饰的钯二十四面体纳米晶。电化学测试结果表明,低的Ru覆盖度(θRu = 0.08)可显著提高对碱性介质中甲醇电氧化的催化性能。电化学原位红外光谱结果表明,少量Ru的修饰没有减少CO的生成,而是促进了低电位下甲醇氧化成甲酸根。
基于室温离子液体的活化石墨烯粉末超级电容储能性能
杨康, 帅骁睿, 杨化超, 严建华, 岑可法
2019, 35(7): 755-765  doi: 10.3866/PKU.WHXB201810009
[摘要]  (42) [HTML全文] (42) [PDF 2913KB] (3)
摘要:
室温离子液体(RTILs)具有电压窗口高等优点,被认为是实现超级电容高性能储能的绿色电解液。但是,离子液体的电导率低、粘度高,使得其储能性能不佳。本文探究了溶剂效应对离子液体超级电容储能性能的影响。以石墨烯粉末为活性材料,选取1-丁基-3-甲基咪唑四氟硼酸盐为离子液体,通过添加乙腈溶剂配置了具有不同摩尔分数ρIL的电解液(从0.25到1.0)。结果表明,溶剂效应对超级电容性能的影响与电压扫描速率或电流密度密切相关。低扫描速率下,溶剂对储能基本没有影响,而高扫描速率下,添加溶剂可显著提升比电容(在ρIL = 0.25时,增加~2倍)。这是由于溶剂削弱了离子-离子间交互作用,从而降低了电解液粘度(~29倍),内阻(~5.5倍)和介电弛豫时间(~6.3倍)。在ρIL = 0.25时,超级电容最大能量和功率密度分别为65.2 Wh·kg-1和18066.6 W·kg-1,显著优于近期文献报道结果。特别地,当工作温度提升到50 ℃时,其能量密度将达到85.5 Wh·kg-1,显著高于传统水系、有机电解液超级电容和铅酸电池,与镍金属氢化物和锂离子电池性能相当。
表面活性剂与叶酸的相互作用及其对光氧化降解的影响
罗思琪, 王美娜, 赵微微, 王毅琳
2019, 35(7): 766-774  doi: 10.3866/PKU.WHXB201809038
[摘要]  (34) [HTML全文] (34) [PDF 998KB] (3)
摘要:
表面活性剂与有机小分子作用不仅能提高表面活性剂的聚集能力,还能提高小分子的溶解度、稳定性等应用性能,因此研究二者之间的相互作用机理对于促进表面活性剂的发展和实际应用具有重要意义。本工作提出了一种利用功能有机小分子调控表面活性剂聚集行为,进而提高不稳定小分子自身稳定性的新策略。利用表面张力、紫外可见吸收光谱、荧光光谱、动态光散射、等温滴定量热和核磁共振技术研究了在pH为7.0时,叶酸分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)、季铵盐Gemini 12-6-12和季铵盐线性三聚12-3-12-3-12四种表面活性剂之间的相互作用及其导致的叶酸光氧化降解性能的变化,结果表明,阴离子表面活性剂SDS抑制叶酸光氧化降解的效率较低,而阳离子表面活性剂都能够显著抑制叶酸的光氧化降解,且随着表面活性剂寡聚度的增加,抑制效果增强,所需表面活性剂的浓度显著降低,寡聚表面活性剂12-3-12-3-12的抑制效率高达96%。
Cu2-MnOx高效催化1, 2, 3, 4-四氢喹啉氧化脱氢芳构化
陈福山, 赵松林, 杨涛, 江涛涛, 倪珺, 张群峰, 李小年
2019, 35(7): 775-786  doi: 10.3866/PKU.WHXB201811046
[摘要]  (50) [HTML全文] (50) [PDF 4594KB] (3)
摘要:
采用新型无模板草酸盐路线制备了系列不同Cu含量的MnOx催化剂(MnOx、Cu1-MnOx、Cu2-MnOx、Cu3-MnOx、Cu4-MnOx、Cu2-450及Cu2-550),并应用于1, 2, 3, 4-四氢喹啉(THQL)氧化脱氢芳构化。通过热重和热流分析(TG-DSC)、X射线衍射(XRD)、N2物理吸附-脱附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱(EDS)、X射线光电子能谱(XPS)、H2程序升温还原(H2-TPR)、原子吸收光谱(AAS)手段对催化剂进行表征。结果显示在这七种锰氧化物中,Cu2-MnOx具有高比表面积、增大的介孔平均孔径、较低的还原温度、最高的Mn3+含量和吸附氧含量,最高的Mn3+/Mn4+。Cu2-MnOx在温和的反应条件下,以廉价的空气为氧化剂、无碱添加剂的情况下对THQL芳构化转化率和喹啉(QL)选择性分别达99.1%、97.2%。催化剂套用五次后转化率还可达95.8%,选择性随着套用次数增加略有降低,这可能是Cu元素的流失所致。催化剂无定型结构、Mn3+和吸附氧含量,Mn3+/Mn4+、晶格氧的流动性及CuO和MnOx的协同作用是高催化活性的关键因素。
ARTICLE
Metal-Organic Framework-Derived Fe-N-C Nanohybrids as Highly-Efficient Oxygen Reduction Catalysts
Qianqian WANG, Dajun LIU, Xingquan HE
2019, 35(7): 740-748  doi: 10.3866/PKU.WHXB201809003
[摘要]  (41) [HTML全文] (41) [PDF 1672KB] (1)
摘要:
Environmentally friendly and renewable energy technologies, such as fuel cells and metal-air batteries, hold great promise for solving current energy and environmental challenges. The oxygen reduction reaction (ORR) plays a pivotal role in this top-drawer question. However, the sluggish kinetics of the ORR and prohibitive costs limit the global scalability of such devices. Traditionally, platinum-based electrocatalysts exhibit the best performance for ORRs in both acid and alkaline electrolytes. However, to significantly reduce the cost and realize sustainable development, utilization of Pt must be replaced or significantly reduced in the ORR cathode for fuel cell applications. Therefore, developing earth-abundant and high-performance non-precious metal catalysts (NPMCs) for ORR is of critical importance for the commercialization of fuel cells. In comparison to traditional catalysts, metal-organic frameworks (MOFs) are ideal precursors that integrate metal, nitrogen, and carbon functionalities together into one ordered 3D crystal structure. MOFs, assembled by secondary building of units comprised of metals and organic linkers with strong bonding, have received significant research attention because they possess permanent porosity, a three-dimensional (3D) structure, and can be prepared using a diversity of metals and organic linkers. High surface area, and microporous carbon materials can be easily obtained by carbonization of MOFs at high temperatures. In particular, MOF-derived carbon nanocomposites, which were prepared from transition metals, and have the form M-N-C (M = Fe or Co), have demonstrated remarkably improved catalytic activity and stability. Herein, we report an NPMC material consisting of Fe3C nanoparticles encapsulated in mesoporous N-doped carbon (Fe-N-C), synthesized by a simple strategy involving physical mixing of MIL-100(Fe) with glucose and urea, and subsequent pyrolysis under inert atmosphere. The strong interaction between metal atoms and nitrogen atoms is beneficial in generating more active sites, and sites with a higher intrinsic catalytic activity, via carbonization. The as-obtained catalysts exhibit remarkable ORR activity in alkaline media, with the best catalyst (Fe-N-C-900, which is synthesized at 900 ℃) featuring a more positive onset potential (0.96 V vs the reversible hydrogen electrode (RHE)), a more positive half-wave potential (0.83 V vs RHE), a much higher diffusion limiting current density (6.28 mA·cm-2) and a larger electron-transfer number (n), even at low overpotentials, compared with other contrast materials. Fe-N-C-900's excellent catalytic activity and stability in ORR are due to its large BET surface area, its large total pore volume, its nitrogen dopants, its active Fe3C nanoparticles and the cooperative effects among its reactive functionalities.

亮点
同分异构的胶体硫化镉半导体幻数团簇的可逆转化
刘忠范
2019, 35(5): 451-452  doi: 10.3866/PKU.WHXB201807016
[摘要]  (73) [HTML全文] (73) [PDF 618KB] (73)
摘要:
异原子占据Ag原子簇的中心核用于催化CO2生成碳碳键的反应
侯文华
2019, 35(5): 453-454  doi: 10.3866/PKU.WHXB201807017
[摘要]  (52) [HTML全文] (52) [PDF 659KB] (52)
摘要:
基于Au@PPy核壳结构纳米粒子自组装阵列的可程序化负微分电阻效应研究
韩布兴
2019, 35(5): 455-456  doi: 10.3866/PKU.WHXB201807063
[摘要]  (58) [HTML全文] (58) [PDF 597KB] (58)
摘要:
当期推荐
弛豫时间分布法分解固体氧化物燃料电池电化学阻抗谱
庄林
2019, 35(5): 457-458  doi: 10.3866/PKU.WHXB201807065
[摘要]  (78) [HTML全文] (78) [PDF 327KB] (78)
摘要:
电荷驱动水中氧化物纳米颗粒自组装的原位透射电子显微镜研究
吴凯
2019, 35(5): 459-460  doi: 10.3866/PKU.WHXB201807077
[摘要]  (56) [HTML全文] (56) [PDF 250KB] (56)
摘要:
综述
有机太阳能电池中基于苝二酰亚胺结构小分子受体进展
邓祎华, 彭爱东, 吴筱曦, 陈华杰, 黄辉
2019, 35(5): 461-471  doi: 10.3866/PKU.WHXB201806073
[摘要]  (68) [HTML全文] (68) [PDF 3012KB] (68)
摘要:
最近几年,有机太阳能电池中的非富勒烯小分子受体研究引起了人们的兴趣。其中,苝二酰亚胺(PDI)类分子因具有良好的电子传输能力,较强的电子亲和力,稳定的光、热、化学性能以及化学结构的可设计性带来的性能可调控性而得到广泛的关注。本文总结了近三年来在体异质结有机太阳能电池应用方面PDI小分子受体的研究进展,重点关注了PDI分子结构对其性能的影响,希望为以后PDI类受体分子的设计思路起到一定的启发作用。
碳基非贵金属氧还原电催化剂的活性位结构研究进展
杨晓冬, 陈驰, 周志有, 孙世刚
2019, 35(5): 472-485  doi: 10.3866/PKU.WHXB201806131
[摘要]  (64) [HTML全文] (64) [PDF 3902KB] (64)
摘要:
以热解型Fe/N/C为代表的碳基非贵金属材料被认为是当前最具潜力替代铂的非贵金属氧还原催化剂,其综合性能的进一步突破,对于推动质子交换膜燃料电池商业化应用具有重要意义。对热解型Fe/N/C催化剂活性位结构的深入认识是实现催化剂高活性位密度和高稳定性理性设计的关键。本文总结了热解型Fe/N/C活性位的研究进展,重点介绍了非晶态铁氮配位活性中心、氮掺杂和碳缺陷三类活性位构型。由于热解型Fe/N/C是非均相的,结构非常复杂,导致在活性位认识上还存在诸多争议,本文总结阐述了活性位结构的不同观点。最后,我们展望了Fe/N/C催化剂活性位研究的未来方向。
论文
正十二烷高温机理简化及验证
卢海涛, 刘富强, 王于蓝, 王成冬, 范雄杰, 刘存喜, 徐纲
2019, 35(5): 486-495  doi: 10.3866/PKU.WHXB201806081
[摘要]  (68) [HTML全文] (68) [PDF 1694KB] (68)
摘要:
由于详细化学反应机理在模拟燃烧室燃烧时,计算量极大,很难被广泛运用。为了满足工程设计要求,采用替代燃料的简化机理进行计算不失为一种行之有效的方法。本文基于误差传播的直接关系图法和敏感性分析法对正十二烷180组分1962步高温机理(温度大于1100 K)进行简化,获得40组分234步化学反应机理。在温度为1100–1650 K,压力为0.1–4 MPa条件下,采用简化机理及详细机理对不同当量比、压力下着火延迟时间进行模拟,模拟结果与实验数据吻合得较好。通过对不同压力及温度下火焰传播速度进行模拟,验证了简化机理能够正确地反映正十二烷的燃烧特性。利用C12H26/OH/H2O/CO2等重要组分随时间变化的数据,验证了简化机理能够准确描述燃烧过程反应物消耗、基团变化、生成物产生的过程,并表明该机理具有较高的模拟精度。利用该简化机理对本生灯进行数值分析,结果表明该机理能够准确地反映火焰区温度和组分浓度的变化。紧凑的正十二烷高温简化机理不仅能够正确体现其物理化学特性,而且能够用于三维数值模拟,具有较高的工程运用价值和应用前景。
固体氧化物燃料电池电化学阻抗谱差异化研究方法和分解
施王影, 贾川, 张永亮, 吕泽伟, 韩敏芳
2019, 35(5): 509-516  doi: 10.3866/PKU.WHXB201806071
[摘要]  (88) [HTML全文] (88) [PDF 1047KB] (88)
摘要:
电化学阻抗谱技术(EIS)在固体氧化物燃料电池(SOFC)中已获得广泛应用。在EIS分析过程中,研究者能够清楚地获得燃料电池内部因纯离子(电子)导电引起的欧姆电阻和因电化学过程、扩散作用引起的极化阻抗的大小,但是对于极化阻抗的构成缺乏进一步解析。本文选用传统的Ni-YSZ阳极支撑电池,通过改变测试温度、阳极运行气氛和阴极运行气氛,设计了一套完整的阻抗差异分析(ADIS)实验。并基于弛豫时间分布法(DRT)和阻抗差异分析法,系统地分析并解释了阻抗谱中各频率段对应阻抗的物理或(电)化学含义,将该类型电池阻抗谱以6个RQ并联电路予以拟合,为之后燃料电池性能稳定性的研究奠定基础。
原位透射电子显微镜观察电荷驱动的氧化物纳米颗粒水中自组装
赵喆, 卢岳, 张振华, 隋曼龄
2019, 35(5): 539-545  doi: 10.3866/PKU.WHXB201806012
[摘要]  (69) [HTML全文] (69) [PDF 2125KB] (69)
摘要:
以四氧化三钴Co3O4纳米棒为研究对象,我们利用液体环境透射电子显微镜,原位观察了四氧化三钴纳米棒在水中的自组装过程。研究发现在电子束辐照的水环境下,四氧化三钴纳米棒的晶面存在互补式自组装现象。随着纳米棒之间的距离越来越近,纳米棒之间的相对运动速率逐渐增加,纳米棒之间的相互作用力逐渐增加。通过进一步分析纳米棒的形貌发现,纳米棒的暴露晶面大多数为{100}、{110}以及{111}晶面,而Co3O4属于极性氧化物,这些晶面往往会带有一定的电荷。在液体环境下,正是由于这些易暴露面都带有不同大小的电荷,在晶面电荷的驱动下,电荷属性相反的四氧化三钴纳米棒会互相吸引,形貌结构上进行互补,实现快速驱动的纳米棒之间自组装。
ARTICLE
Perylenediimide: Phosphonium-Based Binary Blended Small-Molecule Cathode Interlayer for Efficient Fullerene-Free Polymer Solar Cells with Open Circuit Voltage to 1.0 V
Monika GUPTA, Dong YAN, Fugang SHEN, Jianzhong XU, Chuanlang ZHAN
2019, 35(5): 496-502  doi: 10.3866/PKU.WHXB201805101
[摘要]  (68) [HTML全文] (68) [PDF 607KB] (68)
摘要:
The fabrication of high-efficiency organic solar cells requires a cathode interlayer (CIF) having multiple properties such as forming an ohmic contact with the active layer, high electron conductivity, low-density traps, and hole blocking. These roles can be more completely fulfilled by using a suitable binary blended CIF rather than a single molecule based CIF. In this article, we present the roles by using binary blended PDINO (amino N-oxide perylene diimide) and QPhPBr (tetraphenylphosphonium bromide) as the CIF to fabricate fullerene-free polymer solar cells (PSCs) with PBDB-T:IDTBR, a new donor: acceptor combination, as the active layer. The high-lying lowest unoccupied molecular orbital of the acceptor and the low-lying highest occupied molecular orbital (HOMO) of the polymer with small driving force (the donor-acceptor HOMO-HOMO energy offset, ∆HOMO) for the hole transfer, both result in a high open circuit voltage (Voc). Moreover, our strategy to insert a dual mixed solution of CIF over the blended active layer better facilitates the role, which significantly improves charge extraction and collection, leading to the high Voc, short-circuit current density (Jsc), and fill factor (FF) observed in comparison to a single CIF material. It was observed that the power conversion efficiency (PCE) increases to 8.27%, with a high Voc of 1.0 V, using a binary mixture of CBL. Such tremendous improvements in Voc using well known polymer donors have not been reported till date in binary solar cell systems. This idea demonstrates that the minimum energy loss because of the small ∆HOMO of the D-A combination and the use of a dual mixed layer of CBL together present the future prospects of non-fullerene photovoltaic devices for researchers.
Bandgap Modulation of Dithienonaphthalene-Based Small-Molecule Acceptors for Nonfullerene Organic Solar Cells
Meiqi ZHANG, Yunlong MA, Qingdong ZHENG
2019, 35(5): 503-508  doi: 10.3866/PKU.WHXB201805151
[摘要]  (46) [HTML全文] (46) [PDF 1889KB] (46)
摘要:
By using photovoltaic technology, ambient solar light can be directly converted to electricity. The photovoltaic technology has been regarded as one of the most important and promising strategies to resolve the worldwide energy and pollution problems. As one type of photovoltaic technology, polymer solar cells have attracted increasing interest due to their advantages of solution processing capability, low-cost, feasibility to be fabricated on flexible substrates etc. Not until a few years ago, the fullerene derivatives had been dominated the organic photovoltaic field as the most promising acceptor materials for polymer solar cells. However, fullerene-based polymer solar cells have a power conversion efficiency bottleneck due to the relatively fixed energy levels as well as the fixed bandgaps of fullerene derivatives. Therefore, researchers started to develop nonfullerene acceptors which can be used as alternatives to replace the traditional fullerene derivatives. Compared to the fullerene derivatives, nonfullerene acceptors offer several advantages such as stronger light absorption, tunable bandgaps and frontier molecular orbital energy levels. For nonfullerene acceptors, a ladder-type fused ring is usually used as the central core which is an essential building block to tailor the bandgaps and energy levels. Although many fused ring systems have been explored for efficient nonfullerene acceptors, ladder-type angular-shape dithienonaphthalene is seldom reported as the donor unit for nonfullerene acceptors. Furthermore, the impact of thiophene bridge on the optical and photovoltaic properties of the dithienonaphthalene-based nonfullerene acceptors has never been reported. In this context, we report on the design and synthesis of a dithienonaphthalene-based small-molecule acceptor which contains thiophene bridges in between the acceptor terminals and the fused-ring donor core. Compared to the dithienonaphthalene-based small-molecule without the thiophene bridges, the resulting acceptor (DTNIT) exhibits a reduced bandgap of 1.52 eV which makes it more suitable to be blended with the benchmark large bandgap copolymer, poly[(2, 6-(4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1, 2-b: 4, 5-b']dithiophene))-alt-(5, 5-(1', 3'-di-2-thienyl-5', 7'-bis(2-ethylhexyl)benzo[1', 2'-c:4', 5'-c']dithiophene-4, 8-dione)] (PBDB-T). The reduced band-gap of the resulting nonfullerene acceptor can be attributed to its extended π-conjugation in comparison with the dithienonaphthalene-based acceptor without the thiophene bridges. Inverted polymer solar cells with a device configuration of indium tin oxide/ZnO/PBDB-T:DTNIT/MoO3/Ag were fabricated and characterized. Polymer solar cells based on PBDB-T:DTNIT showed an open circuit voltage of 0.91 V, an enhanced short circuit current of 14.42 mA∙cm−2, and a moderate PCE of 7.05% which is comparable to the PCE of 7.12% for the inverted device based on PBDB-T:PC71BM. Our results not only provide a method to synthesize efficient nonfullerene acceptors with reduced bandgaps, but also offer a bandgap modulation strategy for nonfullerene acceptors.
Effect of Ink Solvents on Low-Pt Loading Proton Exchange Membrane Fuel Cell Performance
Wenhui CHEN, Shengli CHEN
2019, 35(5): 517-522  doi: 10.3866/PKU.WHXB201806011
[摘要]  (68) [HTML全文] (68) [PDF 1696KB] (68)
摘要:
Owing to the scarcity of platinum, it is of high importance to develop electrodes with low platinum metal loading and to thereby improve the utilization of Pt for the commercialization of proton-exchange membrane fuel cells (PEMFCs). In comparison to conventional high-platinum electrodes, the thickness of the catalyst layer (CL) is thinner and the interatomic Pt spacing is larger for the low-Pt loading electrodes. The distribution of electrolyte ionomer and the electrode morphology, which are strongly influenced by the solvents used in the fabrication process, are therefore increasingly important factors for achieving high performance in the membrane electrode assembly (MEA). In this work, different solvents with various dielectric constants and evaporation rates were used to prepare the inks for low-Pt loading cathode (0.1 mg·cm-2) fabrication. First, the inks were fabricated by dispersing the catalyst and ionomer in different solvents which were then coated onto carbon paper to prepare the gas diffusion electrodes. The anode and cathode electrodes were then hot-pressed together with the Nafion membrane to produce the MEAs. The results showed a mixture of isopropanol-water (4:1) yielded the best-performing MEA during the single-cell tests compared to the other solvents tested. In order to elucidate the relationship between the performance of MEAs and the solvents, the structure and the surface morphology of the CL and the distribution of Nafion ionomer in the CL was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A comparison of the SEM and TEM images of representative samples indicated that the best performing electrode had a much improved homogeneity in the surface morphology as well as the dispersion of catalyst and ionomer. This was because of the moderate evaporation rate and better dispersion, caused by the increased hydrogen bonding and high dielectric constant, respectively. The results from dynamic light scattering (DLS) showed that the size of the catalyst and ionomer aggregates are influenced by the solvents. It is suggested that larger aggregates might help the formation of holes in the CL for gas diffusion and water removal, with the optimum size found to be around 400–800 nm. In conclusion, the MEA fabricated from the isopropanol-water solvent exhibited a significantly increased power density (1.79 W·cm-2), and the utilization of Pt was increased to approximately 0.047 mg·W-1, which is among the best-performing fuel cells reported to date.
Molybdenum Carbide Prepared by a Salt Sealing Approach as an Electrocatalyst for Enhanced Hydrogen Evolution Reaction
Zhou LIN, Linfan SHEN, Ximing QU, Junming ZHANG, Yanxia JIANG, Shigang SUN
2019, 35(5): 523-530  doi: 10.3866/PKU.WHXB201806191
[摘要]  (74) [HTML全文] (74) [PDF 1571KB] (74)
摘要:
Molybdenum carbide is regarded as an excellent substitute for Pt-based catalysts in the hydrogen evolution reaction (HER), owing to its low cost, superior catalytic performance, and long-term stability. In this work, salt-sealed molybdenum carbide was prepared using sodium molybdate and 2, 6-diaminopyridine as the reactive raw materials, followed by continuous salt sealing and calcination of the precursor under an inert atmosphere. The morphology, composition and structure of salt-sealed molybdenum carbide were determined by scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicate that salt-sealed molybdenum carbide has irregular morphology and includes nanoparticles and nanorods. A comparison of the TEM images of Mo2C with salt sealing (Mo2C/SS) and Mo2C without salt sealing (Mo2C) indicates that Mo2C/SS exhibits a smaller particle size. This suggests that salt sealing can efficiently avoid particle aggregation. The Brunauer-Emmett- Teller (BET) specific surface area of the catalysts was obtained from nitrogen adsorption/desorption isotherms. The increase in BET surface area from 2.55 to 8.14 m2·g−1 after salt sealing provides evidence for the formation of pores in the product. The results of XRD, EDS and XPS analyses show that Mo2C/SS has an orthorhombic crystal structure with molybdenum oxides on the surface, which may originate from surface oxidation. Considering the results of XPS and the turnover frequency (TOF) calculation, we can conclude that the formation of pores via salt sealing contributes to the exposure of more active sites, while simultaneously enlarging the contact area with oxygen. Therefore, higher molybdenum oxide content is generated on the surface, resulting in a lower proportion of active centers (molybdenum carbides) on the catalyst surface. Furthermore, the pseudocapacitance generated by the faradaic reaction of molybdenum oxides is superimposed on the double-layer capacitance of Mo2C catalysts, which increases the double layer capacitance. Since the effect of pseudo-capacitance on Mo2C/SS is more significant, the TOF number declines after salt sealing. Compared with Mo2C, Mo2C/SS exhibits three features that promote HER mass activity: (1) the generation of large quantities of pores via salt sealing leads to an increase in the BET surface area and exposure of more active sites, which is beneficial for improving HER performance; (2) the porous structure and enlarged surface area pave the way for effective mass and charge transfer; (3) the decrease of the Tafel slope from 145 to 88 mV·dec−1. In summary, salt-sealed Mo2C exhibited enhanced HER activity with an overpotential of 175 mV to achieve a current density of 10 mA·cm−2. The Tafel slope for HER on salt-sealed Mo2C is 88 mV·dec−1. This can be considered as the proof of the Volmer-Heyrovsky mechanism with electrochemical desorption as the rate-determining step.
Reactivities of VO1–4+ Toward n-CmH2m+2 (m = 3, 5, 7) as Functions of Oxygen Content and Carbon Chain Length
Yue ZHAO, Jiatong CUI, Jichuang HU, Jiabi MA
2019, 35(5): 531-538  doi: 10.3866/PKU.WHXB201805231
[摘要]  (73) [HTML全文] (73) [PDF 1506KB] (73)
摘要:
Vanadium oxides are one of the most important heterogeneous catalysts that are widely used to oxidize hydrocarbon molecules into value-added chemicals. In order to reveal the mechanisms and the nature of active sites, numerous experimental and theoretical studies have been reported on the reactivities of gas-phase vanadium oxide clusters toward small molecules. However, there has been very limited research on the chemical reactivity changes associated with the oxygen contents of vanadium oxides and the carbon chain lengths of alkanes. In this work, the reactions of vanadium oxide ions VO1−4+ with alkanes (n-CmH2m+2, m = 3, 5, 7) were systematically investigated by time-of-flight mass spectrometry and the reactions of VO1−3+ with pentane were further studied by density functional theory calculations. Experimental results show that in the reactions of VO+, VO3+, and VO4+ with n-C5H12, in addition to the major adsorption processes, the activation of the C―H and C―C bonds of n-C5H12 was observed. The activation of both the bonds was observed experimentally during the reaction of VO2+ with n-C5H12 with large branching ratios. Among the vanadium oxide cations studied, VO2+ shows the strongest oxidizability and the generation of lighter alkanes and alkenes dominates the reactions; VO+ is more reactive than VO3+. VO4+ pocesses only one η2-O2 unit. Due to the weak bond between VO2+ and η2-O2, the η2-O2 unit is released in VO4+/n-C5H12 system leading to the formation of VO2+; thus VO4+ cations reflect some reactivity of VO2+. Although the oxidation states in the vanadium oxide clusters increase from +Ⅲ in VO+ to +Ⅴ in VO2+ and +Ⅳ in VO3+, the reactivity does not gradually increase. Moreover, the reactivity of the mononuclear vanadium oxide cations also does not exhibit a gradually increasing trend with the increase in oxygen content. Based on the observed reactivity trend, the adsorption channels gradually become weak as the carbon chain lengths increase; meanwhile, the dehydrogenation and C―C bond activation channels gradually become obvious and some oxygen transfer products appear. Therefore, much lighter fragments of alkanes/alkenes will be obtained if linear alkanes with more carbon atoms were reacted with VO1−4+. The theoretical results are generally consistent with those obtained from the experiments. The various reaction channels and versatile reactivity of the mononuclear vanadium oxide cations investigated in this study not only offer new insights into gas-phase reactions but also shed light on the processes occurring on the surfaces of the corresponding condensed-phase catalysts.
Single-Molecule Study on the Folding of OmpT in Tween-20 Micelles
Peixuan BU, Chenhui HE, Xinsheng ZHAO
2019, 35(5): 546-554  doi: 10.3866/PKU.WHXB201806072
[摘要]  (77) [HTML全文] (77) [PDF 1439KB] (77)
摘要:
The cell envelope of gram-negative bacteria consists of the outer membrane (OM), inner membrane (IM), and periplasm. The β-barrel outer membrane proteins (OMPs) embedded in the OM perform diverse and significant functions such as signaling, transporting, and proteolysis. The OMPs of gram-negative bacteria share similar folding pathways with that of mitochondria and chloroplasts. Therefore, the study of the OMP folding mechanism not only provides insights into antimicrobial drug design but also helps elucidate mitochondrial and chloroplast biogenesis. Most knowledge about OMP folding was obtained from ensemble experiments where OMPs were usually at micromolar concentrations and prone to aggregate, which is different from the physiological environment in the cells. Unlike ensemble techniques, single-molecule detection (SMD) can measure OMPs from nano- to picomolar concentrations and prevent aggregation. In this work, we investigated the folding of OmpT, one of the OMPs, in Tween-20 and n-dodecyl β-d-maltopyranoside (DDM) micelles by SMD. We prepared monodisperse OmpT and observed both unfolded and folded OmpT in Tween-20 and DDM micelles under different urea concentrations by single-molecule fluorescence resonance energy transfer (FRET). The folded OmpT in Tween-20 is structurally similar to the native OmpT folded in DDM but exhibits weaker resistance to urea. In contrast, OmpA barely folds and OmpC hardly folds in Tween-20 micelles. We confirmed that folded OmpT forms complexes with detergent micelles and estimated the number of bound Tween-20 and DDM molecules per OmpT by fluorescence correlation spectroscopy. We compared the enzymatic activity of OmpT folded in two detergents with a fluorescent peptide as substrate, and found that the folded form of OmpT in Tween-20 possesses weaker enzymatic activity than that in DDM. We also investigated the folding properties of OmpT, OmpA, and OmpC in the presence of the β-barrel assembly machine (BAM) complex. OmpT folds efficiently in liposome even without the BAM complex; OmpA only folds with the help of the BAM complex; and OmpC does not fold with or without the BAM complex. Based on the comparison of the folding of OmpT, OmpA, and OmpC in detergent micelles and in the presence of the BAM complex, we propose that OmpT has stronger folding tendency than OmpA and OmpC, which supports the idea that the exact role of the BAM complex is dependent on the distinct folding properties of individual OMPs. Since Tween-20 is a widely used reagent to block nonspecific adsorption in SMD experiments, our results also remind people to exercise caution to prevent possible wrong interpretations caused by the interaction between proteins and Tween-20.

编委会

发布时间:


《物理化学学报》第4届编委会

(按拼音排序)

名誉主编

唐有祺

北京大学

顾问编委

包信和

中国科学院大连化学物理研究所

段雪

北京化工大学

付贤智

福州大学

侯建国

中国科学技术大学

黄维

南京工业大学

LIEBER Charles M.

Harvard University

田中群

厦门大学

万立骏

中国科学院化学研究所

吴云东

北京大学

谢晓亮

Harvard University, 北京大学

杨伟涛

 Duke University

姚建年

中国科学院化学研究所

赵新生

北京大学

主编

刘忠范

北京大学

副主编

韩布兴

中国科学院化学研究所

刘鸣华

国家纳米科学中心

申文杰

中国科学院大连化学物理研究所

吴凯

北京大学

杨金龙

中国科学技术大学

庄林

武汉大学

迟力峰

苏州大学

编委

曹勇

复旦大学

陈经广

University of Delaware

陈军

南开大学

崔屹

Stanford University

邓风

中国科学院武汉物理与数学研究所

邓友全

中国科学院兰州化学物理研究所

樊卫斌

中国科学院山西煤炭化学研究所

房喻

陕西师范大学

付红兵

中国科学院化学研究所

傅强

中国科学院大连化学物理研究所

高毅勤

北京大学

郭林

北京航空航天大学

郝京诚

山东大学

侯文华

南京大学

金荣超

Carnegie Mellon University

来鲁华

北京大学

李朝军

McGill University

李隽

清华大学

李象远

四川大学

梁万珍

厦门大学

刘海超

北京大学

刘洪来

华东理工大学

刘述斌

University of North Carolina

刘义

武汉大学

刘志敏

中国科学院化学研究所

罗小民

中国科学院上海药物研究所

马晶

南京大学

孟庆波

中国科学院物理研究所

邵翔

中国科学技术大学

孙俊奇

吉林大学

谭蔚泓

湖南大学

唐智勇

国家纳米科学中心

王键吉

河南师范大学

王鹏

中国科学院长春应用化学研究所

王心晨

福州大学

王永锋

北京大学

魏子栋

重庆大学

翁羽翔

中国科学院物理研究所

吴鹏

华东师范大学

夏永姚

复旦大学

许国勤

National University of Singapore

杨俊林

国家自然科学基金委员会

余家国

武汉理工大学

尉志武

清华大学

占肖卫

北京大学

张东辉

中国科学院大连化学物理研究所

张浩力

兰州大学

张锦

北京大学

章俊良

上海交通大学

周永贵

中国科学院大连化学物理研究所

联系我们

发布时间: 2018-05-02


编辑部工作人员联系方式
 

张小娟
主任
010-62756388
黄路
编辑
010-62751724
欧阳贱华
编辑
010-62751721
於秀芝
编辑
010-62751724
熊英
编辑
010-62751724
周虹
技术编辑
010-62751724

 

通讯地址:北京市北京大学化学学院物理化学学报编辑部

邮政编码:100871

 

发布日期:2009-06-24 浏览: