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Self-Assembly and Structural Characterization of Au Binary Nanocrystal Superlattices
Yanan Zhao, Min He, Xiaofang Liu, Bin Liu, Jianhui Yang
2020, 36(9): 1908041-0  doi: 10.3866/PKU.WHXB201908041
[摘要]  (29) [PDF 2315KB] (1)
摘要:
The assembly of two-component nanocrystals (NCs) such as metals, magnets, and semiconductors into binary nanocrystal superlattices (BNSLs) provides a fabrication route to novel classes of materials. BNSLs with certain structures can exhibit the combined and collective properties of their building blocks and are widespread in the fields of electronics and magnetic devices. As most studies have focused on combined two-component NCs of different sizes for self-assembling BNSLs, there are a few studies on single-component NCs of different sizes for the construction of BNSLs; this is especially true for Au NCs. Noble metallic Au NCs are an excellent candidate material because of their exceptional chemical stability, catalytic activity, process ability, and metallic nature; these characteristics provide them unique size-dependent optical and electronic properties as well as a wide variety of applications in sensing, imaging, electronic devices, medical diagnostics, and cancer therapeutics owing to their strong interactions with external electromagnetic fields. Therefore, it is important to develop a simple and efficient procedure to build BNSLs with different sizes of Au NCs. In our study, we synthesized monodispersed (size distribution < 10%) 6.0, 7.3, and 9.6 nm Au NCs using dodecanethiol-stabilized 3.7 nm Au NCs as seeds through a seed-growth method in oleylamine. The obtained Au NCs exhibited morphology and nanocrystallinity (single-domain and polycrystalline) similar to those of Au seeds. As the size of Au NCs increased from 3.7 to 6.0, 7.3, and 9.6 nm, the surface plasmon resonance peaks narrowed and indicated a red shift. The oleylamine-functionalized 6.0, 7.3, and 9.6 nm Au NCs were mixed with 3.7 nm Au NCs at certain concentration ratios. Au BNSLs with AB2 (hexagonal AlB2 structure), AB13 (NaZn13 structure), and AB (cubic NaCl structure) type were obtained through the solvent evaporation method. The (001) plane of the AlB2-type structure, (001) plane of the NaZn13-type structure, and (100) plane of NaCl-type structure superlattices were observed through transmission electron microscopy (TEM). The effective particle size ratios (γ= Dsmall/Dlarge) serve as the critical determining factor in the formation of the BNSLs. The effective particle size of NCs is equal to the sum of the metal core diameter and twice the thicknesses of the surface ligand. In our study, the effective particle size Dsmall (Au seed) is 5.7 nm; the effective particle sizes Dlarge (6.0, 7.3, and 9.6 nm Au NCs) are 9.0, 10.3, and 12.6 nm, respectively. The effective particle size ratios γ were therefore calculated to be 0.63, 0.55, and 0.45, respectively. The relevant space filling principle predicted the stability of the AlB2, NaZn13, and NaCl-type structures in the range of 0.482 < γ < 0.624, 0.54 < γ < 0.625, and γ < 0.458, respectively; the experimental results adequately matched the relevant space filling principle. The investigation of such a single nanocomponent as a building block is noteworthy with regard to the structures and properties of BNSLs as well as the potential development of novel meta-materials.
Redox-Regulated Dynamic Self-Assembly of a Lindqvist-Type Polyoxometalate Complex
Jing Zhang, Lina Wang, Xiaofei Chen, Yufeng Wang, Chengyan Niu, Lixin Wu, Zhiyong Tang
2020, 36(9): 1912002-0  doi: 10.3866/PKU.WHXB201912002
[摘要]  (19) [PDF 1250KB] (0)
摘要:
Dynamic regulation of self-assembly is of vital importance in chemistry, biology and material science thanks to its great potential for development of smart materials and devices. Polyoxometalates (POMs) are a class of functional inorganic nanoclusters, which has become one of the excellent building blocks for supramolecular self-assemblies, especially when covalently or non-covalently modified by organic species. As typical stimuli-responsive functional clusters, the POMs could be photochemically or electrochemically reduced to mixed-valence states, of which the structural integrity remains even after encountering stepwise multi-electron redox process. The intriguing photochromism of the POMs in different states exhibits distinct photophysical properties, which motivates us to exploit the dynamic self-assemblies of POM-based complexes. The divalent Lindqvist-type hexamolybdate cluster [Mo6O19]2- is one of the least negative-charged POMs, which is the ideal building blocks to construct novel assembly structures. Based on this motivation, herein, a single chain surfactant-encapsulated polyoxometalate (POM) complex (ODTA)2[Mo6O19] was prepared by simple counterion replacement of Lindqvist-type (TBA)2[Mo6O19] with octadecyltrimethylammonium (ODTA) in acetonitrile solution. The structure of the POM complex was confirmed by 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis. The solution of complex (ODTA)2[Mo6O19] in the mixed solvents of acetonitrile and isopropanol with the volume ration of 4 to 1 exhibited reversible photochromism upon alternate UV light irradiation and air exposure. Upon UV light irradiation, the light yellow transparent solution of (ODTA)2[Mo6O19] turned into blue quickly. The new broad absorption band appearing at ca.751 nm assigned to the MoV → MoVI intervalence charge-transfer (IVCT) transition, indicated the formation of reduced POM, as revealed by UV-Vis absorption spectra. After exposed to air, the blue solution was bleached. The alternate photochromism could be conducted for multiple cycles. Helical self-assembled morphology of (ODTA)2[Mo6O19] was formed in acetonitrile/isopropanol, characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods. More interestingly, morphology transformation of the complex from helical strips to spherical assemblies occurred accompanied by photochromism occurrence. The morphology evolution during the photochromism process experienced from shortened helical strips through sea urchin-like aggregates to spherical assemblies. Most significantly, the helical assemblies could be recovered again after air oxidation, implying the reversible morphology transformation driven by redox stimulus. The redox-modulated reversible self-assembly is driven by the variation of electrostatic attraction between organic cations and inorganic anions as well as the electrostatic repulsion between inorganic ionic clusters, proved by X-ray photoelectron spectroscopy (XPS) and 1H NMR spectra. The results will contribute to better understanding the mechanism of dynamic assemblies and inspire the precise fabrication of advanced smart materials.
Controlled Synthesis of Lanthanide-titanium Oxo Clusters EuTi6, EuTi7 and La2Ti14
Yamei Yang, Huijie Lun, Lasheng Long, Xiangjian Kong, Lansun Zheng
2020, 36(9): 1912007-0  doi: 10.3866/PKU.WHXB201912007
[摘要]  (18) [PDF 1963KB] (0)
摘要:
As opposed to nanoparticles, atomically precise metal clusters possess a well-defined surface and crystal structure, which aids in understanding the relationship between the structure and chemical reactivity at the atomic level. As an interesting subgroup of metal cluster compounds, heterometallic lanthanide-titanium oxo clusters (LnTOCs) have attracted extensive attention due to their interesting chemical properties. However, the controlled precise synthesis of LnTOCs remains a great challenge because of the intense hydrolysis of Ti4+ ions and the competitive coordination of Ln3+ ions. Owing to this synthetic difficulty, high-nuclearity LnTOCs are very rare, which obstructs further studies on their properties. Choosing the appropriate chelating ligands should be an effective strategy to synthesize LnTOCs because chelating ligands can reduce the degree of hydrolysis of Ti4+ ions. Herein, four new LnTOCs, formulated as [EuTi6(μ3-O)3(OC2H5)8(dtbsa)6(Hdtbsa)]·(C2H5OH) (1), [EuTi7(μ3-O)3(μ2-OH)2(OiPr)9(dtbsa)6(Hdtbsa)Cl]·(HOiPr)3 (2), [EuTi7(μ3-O)3(μ2-OH)2(OiPr)8(dtbsa)7(Hdtbsa)]·(HOiPr)3 (3), and [LaTi7(μ3-O)3(μ2-OH)2(OC2H5)8(dtbsa)7(Hdtbsa)]2·(C2H5OH)4 (4), were prepared by a solvothermal method via the reaction of 3, 5-di-tert-butylsalicylic acid (H2dtbsa), rare-earth salts, and Ti(OiPr)4. Single-crystal analysis showed that the heptanuclear compound 1 contains a EuTi6 metal core featuring a trigonal prismatic structure, wherein Eu3+ is located at the center of the prism formed by six Ti4+ ions. The metal core structure of octanuclear compounds 2 and 3 can be viewed as the EuTi6 unit in 1 connected to another Ti4+ on one side of the triangular prism. The metal framework of Ln2Ti14 in 4 can be regarded as a dimer of EuTi7 in 2. UV-Vis diffuse reflectance spectra revealed that the band gaps of 1, 2, and 3 (2.35, 2.07, and 2.16 eV, respectively) are significantly smaller than that of anatase (3.2 eV). The results of photoelectric tests indicated that the three clusters show an obvious photoelectric response, and the charge separation efficiency of 1 and 2 was better than that of 3. In order to explore the applications of these compounds to photocatalysis, H2 production by light-driven water splitting under irradiation by a 300 W Xe lamp (300–800 nm) in an aqueous methanol solution (20 mL, 10%) was attempted. The H2 production rates for 1, 2, and 3 were 112, 106, and 87 μmol∙h-1∙g-1, respectively, which were higher than that obtained with the commercial P25. Powder X-ray diffraction (PXRD) spectra and thermogravimetry (TGA) profiles confirmed the optical and thermal stability of the three clusters. This work not only provides a chelating ligand strategy for the synthesis of LnTOCs but also reveals their light-driven photocatalytic activity stemming from the small band-gap.
CVD Grown Carbon Nanotubes on Reticulated Skeleton for Brine Desalination
Hui Xiong, Xinwen Xie, Miao Wang, Yaqi Hou, Xu Hou
2020, 36(9): 1912008-0  doi: 10.3866/PKU.WHXB201912008
[摘要]  (19) [PDF 3284KB] (2)
摘要:
Using solar energy to power evaporative processes has found various applications in desalination, wastewater treatment, and power generation among other fields. Due to its green-energy sources and energy-efficient conversions, it has gained increasing attention. However, as one of the oldest approaches, the application of solar evaporation is still limited by issues such as low evaporation efficiency, fouling, and the rapid degradation of solar absorbers. During solar evaporation processes, the solar absorbing materials are directly heated by sunlight and the generated heat is transferred to the water around the material. Within this process, in situ photo-thermal conversion is realized by absorber materials at the air-water interface. After the water is heated, it vapors continuously. Therefore, the material for solar absorption and photo-thermal conversion is key to improving the efficiency of solar evaporation processes. Currently, many approaches are being developed to achieve high-efficient solar evaporation, such as the photon management, nano-scale thermal regulation, the development of new photo-thermal conversion materials, and the design of efficient light-absorbing solar stiller. Carbon-based materials including carbon nanotubes, graphene, carbon black, graphite, etc. have broad light-absorption profiles over the entire solar spectrum, which makes them the outstanding photo-thermal conversion materials. Herein, we design a new structure and house-like solar still on the basis of carbon-based materials to achieve high light absorption, efficient photo-thermal conversion, and continuous desalination. We use the chemical vapor deposition (CVD) technique to fabricate a reticulated carbon-nanotube solar evaporation membrane. Stainless steel mesh (SSM) is used as a reticulated skeleton, providing porous structures and increasing the mechanical strength of the membrane. Then the carbon nanotubes (CNTs) are grown on the reticulated skeleton to function as solar conversion structures due to their wide range of light absorption capacities. The CVD grown CNTs reticulated membrane (CGRM) is fixed in a house-like device with a sloped ceiling to condense and collect water vapors ensuring the continuous desalination of water. Our experiments show that the fabricated CGRM is hydrophobic with an average contact angle of 133.4° for a 100.0 g·L-1 NaCl solution, only allowing water vapors to pass through while rejecting salts. When the light intensity was 1 kW·m-2, the surface temperature of the membrane increased rapidly and stabilized at 84.37 ℃. The salt rejection rate of the system could reach up to 99.92%.To perform a comparative study, we also prepared a mechanically-filled CNTs reticulated membrane (MFRM1, MFRM2) for solar evaporation tests, which showed an inferior performance to that of the growing structure of the CGRM. Therefore, it was determined that our system might provide a potential way to harvest freshwater readily with portable-type equipment.
Rh-Doped PdCu Ordered Intermetallics for Enhanced Oxygen Reduction Electrocatalysis with Superior Methanol Tolerance
Menggang Li, Zhonghong Xia, Yarong Huang, Lu Tao, Yuguang Chao, Kun Yin, Wenxiu Yang, Weiwei Yang, Yongsheng Yu, Shaojun Guo
2020, 36(9): 1912049-0  doi: 10.3866/PKU.WHXB201912049
[摘要]  (22) [PDF 2535KB] (0)
摘要:
Direct methanol fuel cells (DMFCs), as one of the important energy conversion devices, are of great interest in the fields of energy, catalysis and materials. However, the application of DMFCs is presently challenged because of the limited activity and durability of cathode catalysts as well as the poisoning issues caused by methanol permeation to the cathode during operation. Herein, we report a new class of Rh-doped PdCu nanoparticles (NPs) with ordered intermetallic structure for enhancing the activity and durability of the cathode for oxygen reduction reaction (ORR) and achieving superior methanol tolerance. The disordered Rh-doped PdCu NPs can be prepared via a simple wet-chemical method, followed by annealing to convert it to ordered phases. The results of transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), power X-ray diffraction (PXRD) analysis and high resolution TEM (HRTEM) successfully demonstrate the formation of near-spherical NPs with an average size of 6.5 ± 0.5 nm and the conversion of the phase structure. The complete phase transition temperatures of Rh-doped PdCu NPs and PdCu are 500 and 400 ℃, respectively. The molar ratio of Rh/Pd/Cu in the as-synthesized Rh-doped PdCu NPs is 5/48/47. Benefitting from Rh doping and the presence of the ordered intermetallic structure, the Rh-doped PdCu intermetallic electrocatalyst achieves the maximum ORR mass activity of 0.96 A·mg-1 at 0.9 V versus reversible hydrogen electrode (RHE) under alkaline conditions—a 7.4-fold enhancement compared to the commercial Pt/C catalyst. For different electrocatalysts, the ORR activities follow the sequence, ordered Rh-doped PdCu intermetallics > ordered PdCu intermetallics > disordered Rh-doped PdCu NPs > disordered PdCu NPs > commercial Pt/C catalyst. In addition, the distinct structure endows the Rh-doped PdCu intermetallics with highly stable ORR durability with unaltered half-wave potential (E1/2) and mass activity after continuous 20000 cycles, which are higher than those of other electrocatalysts. Furthermore, the E1/2 of the Rh-doped PdCu intermetallics decreases by only 5 mV after adding 0.5 mol·L-1 methanol to the electrolyte, while the commercial Pt/C catalyst negatively shifts by 235 mV and a distinct oxidation peak can be observed. The results indicate that the ORR activity of the Rh-doped PdCu intermetallic electrocatalyst can be well maintained even in the presence of poisoning environment. Our results have demonstrated that Rh-doped PdCu NPs with ordered intermetallic structures is a potential electrocatalyst toward the next-generation high-performance DMFCs.
Feature Article
Solid Frustrated Lewis Pairs Constructed on CeO2 for Small-Molecule Activation
Sai Zhang, Mingkai Zhang, Yongquan Qu
2020, 36(9): 1911050-0  doi: 10.3866/PKU.WHXB201911050
[摘要]  (15) [PDF 3771KB] (1)
摘要:
Solid materials containing frustrated Lewis pairs (FLPs) as active sites have attracted much attention due to their ability to activate and transform small molecules. However, it is still highly challenging to precisely construct FLP sites on the surfaces of nanomaterials, thereby limiting the applications of these materials. Nanostructured ceria (CeO2) is commonly employed as a catalyst or functional support, and exhibits both Lewis acid and basic properties as well as abundant and easily regulated surface defects, which originate from the reversible Ce3+/Ce4+ redox pair. When the Lewis acid and base sites of CeO2 are independent of each other, the combined Lewis acid-base sites play a similar role to that of homogeneous FLP sites. Thus, the rich surface properties of nanostructured CeO2 provide significant potential for the construction of solid FLPs.Herein, we demonstrate that solid FLP sites can be successfully constructed on the surface of CeO2(110) via the regulation of surface defect clusters, which can be used to create new Lewis acid sites composed of two adjacent Ce3+ atoms on the surface. Novel interfacial FLP sites can then be formed by combining these Lewis acid sites with neighboring surface lattice oxygens, which act as Lewis base sites. Porous CeO2 nanorods (PN-CeO2) with boundary surface defects were prepared by a special two-step hydrothermal process, and exhibited remarkable catalytic FLP properties. Hydrogen molecules could be effectively activated on the surface of PN-CeO2 with a low activation energy of 0.17 eV via a heterolytic cleavage process. Hydrogenation of alkenes and alkynes to alkanes could then be realized by the activated hydrogen under mild reaction conditions.PN-CeO2 nanorods with FLP active sites were also able to activate CO2 molecules effectively. Unlike in other solid FLP sites, CO2 molecule activation was realized via a Lewis base site binding with the C atom while two Lewis acid sites bound the two O atoms, owing to the unique configuration of the FLP sites in PN-CeO2. When combined with the epoxidation of olefins by "isolated" Ce3+ sites in PN-CeO2, the FLP-inspired activated CO2 could be used to transform olefins and CO2 to cyclic carbonates through a selective tandem transformation route. In addition, density functional theory studies indicate that the FLP sites on CeO2(110) can activate the C―H bond of CH4 with activation energies as low as 0.63 eV, which can be attributed to the enhanced acidity and basicity of the FLP sites.With this improved understanding of solid FLP sites constructed on ceria, we have also been able to summarize the challenges and prospects in this field, including their construction, characterization, and mechanism analysis.
综述
纳米粒子的精准组装
李凯旋, 张泰隆, 李会增, 李明珠, 宋延林
2020, 36(9): 1911057-0  doi: 10.3866/PKU.WHXB201911057
[摘要]  (25) [PDF 10677KB] (4)
摘要:
纳米材料由于其独特的光、电、磁、力学等性质,成为了构建功能材料与器件的理想基元。实现纳米粒子的精确组装,是探究粒子之间的耦合聚集性质和制备宏观功能器件的基础。但是由于纳米粒子的小尺寸以及在溶液中运动的随机性与复杂性,精准控制纳米粒子组装体的形貌以及在空间中的相对位置仍存在巨大挑战。为了将纳米粒子组装成理想的有序结构,许多控制粒子组装的策略与方法得到发展。本文首先概述了纳米粒子自组装的控制方法与典型形貌,着重分析了影响粒子精准排布的因素与控制方法,并对纳米粒子及其组装体的光学性质与器件应用的最新研究进展进行了讨论,最后对目前纳米粒子精准组装所面临的挑战以及未来发展的方向进行了展望。
单层类水滑石纳米片的可控合成及规模生产展望
李天, 郝晓杰, 白莎, 赵宇飞, 宋宇飞
2020, 36(9): 1912005-0  doi: 10.3866/PKU.WHXB201912005
[摘要]  (21) [PDF 6362KB] (4)
摘要:
水滑石(LDHs)是一种阴离子黏土材料,由于其主体层板厚度的可调性,使其在光/电催化、电池、超级电容器、传感器以及生物医药等领域都具有广泛应用。降低层厚至单层可使材料的物理化学性质发生根本改变,从而优化催化性能。近期研究表明,利用自上而下,自下而上的方法,可以实现单层LDHs类材料的合成,但是受限于产量(g级)以及成本设备等问题,目前规模化制备高质量单层LDHs类材料还没有工业案例。成核晶化隔离法是目前唯一规模化合成纳米LDHs的工业化方法,具有成本低,产量可吨级放大等优点。本综述从合成方法、表征手段、应用三个角度讨论了单层及超薄LDHs的精准调控,详细论述了近期关于单层及超薄LDHs合成突破以及LDHs的规模化生产进展,并对其性能进行了总结,为后续设计高性能单层LDHs提供思路。
金纳米复合材料:制备、性质及其癌症诊疗应用
凌云云, 夏云生
2020, 36(9): 1912006-0  doi: 10.3866/PKU.WHXB201912006
[摘要]  (26) [PDF 6184KB] (0)
摘要:
由于可调的局域表面等离子体共振、丰富的表面可修饰性、良好的生物相容性,金纳米粒子(AuNPs)在生物医药领域具有广泛的应用前景。金与其他无机纳米粒子相结合,既集成了单个组分的性质又有望开发组分间的协同效应,这为构建多功能金纳米复合材料提供了基础。本文阐述了金纳米复合材料的制备方法,包括一步合成法,种子生长法及非原位组装法等;对近期金纳米复合材料在癌症诊疗方面的应用进行总结;最后,讨论了多功能金纳米诊疗平台存在的主要问题及未来发展前景。
铂基金属间化合物纳米晶的最新进展:可控合成与电催化应用
杨天怡, 崔铖, 戎宏盼, 张加涛, 王定胜
2020, 36(9): 2003047-0  doi: 10.3866/PKU.WHXB202003047
[摘要]  (12) [PDF 7178KB] (1)
摘要:
铂基金属间化合物纳米晶因其高度有序的结构特点,优异的抗氧化及耐腐蚀性能,作为电极材料被广泛应用于各类电催化反应,目前已有的PtCo金属间化合物纳米晶在燃料电池阴极反应(氧还原反应)中的活性和稳定性均达到了美国能源部(DOE) 2020年的目标。为了进一步提高金属间化合物纳米晶的电催化性能,需要对影响纳米晶电催化性能的因素进行深入研究。本文综述了铂基金属间化合物纳米晶的研究现状,着重介绍了铂基金属间化合物的可控合成策略及其在电催化领域的最新研究进展,分析总结了该领域存在的问题,并展望了其未来发展方向。
Communication
Rational Design of a Core-Shell Rh@Zeolite Catalyst for Selective Diene Hydrogenation
Jian Zhang, Liang Wang, Zhiyi Wu, Chengtao Wang, Zerui Su, Feng-Shou Xiao
2020, 36(9): 1912001-0  doi: 10.3866/PKU.WHXB201912001
[摘要]  (22) [PDF 1882KB] (0)
摘要:
Selective hydrogenation of dienes and alkynes to monoenes is an important topic of research in the fields of pharmacology and organic synthesis. Catalyst design plays a key role in this process, where a general principle involves controlling the steric diene adsorption by modifying the surface of the metal nanoparticles. For example, upon introducing Bi species into Rh nanoparticles, the resulting RhBi/SiO2 showed 90% selectivity to 2-hexene, with 95% conversion of 1, 4-hexadiene under ambient conditions, because of the suppressed adsorption of the internal C=C bond. However, the catalyst activity decreased remarkably; that is, the activity of the unmodified Rh/SiO2 was about 27 times higher than that of RhBi/SiO2. Controlled steric adsorption of the diene molecules could also be achieved by the constructing porous channels around the metal nanoparticles. For example, metal-organic framework (ZIF-8) or mesoporous silica (MCM-41) encapsulated noble metals showed high selectivity for the hydrogenation of terminal C=C bonds. However, these catalysts had poor durability under the thermal/hydrothermal reaction/regeneration conditions. In contrast, zeolites have superior durability under harsh reaction conditions, but they are rarely used in semi-hydrogenation reactions. We recently found that metal nanoparticles fixed within zeolite crystals (e.g., ZSM-5 and Beta) efficiently catalyze the selective hydrogenation of molecules bearing multiple reducible groups. Thus inspired, we developed a catalyst by fixing Rh nanoparticles within zeolite crystals via an inter-zeolite transformation method. The Rh@CHA catalyst was synthesized by introducing Rh species into the parent Y zeolite (Rh@Y) and transformation of the Y zeolite to chabazite (CHA zeolite) under hydrothermal conditions. X-ray diffraction patterns, N2 sorption isotherms, scanning/transmission electron microscopy images, and model reactions (hydrogenation of probe molecules) confirmed the successful fixation of the Rh nanoparticles inside the CHA zeolite crystals. As expected, the Rh@CHA catalyst was highly selective for the hydrogenation of dienes. For example, Rh@CHA showed a 2-hexene selectivity of 86.7%, with 91.2% conversion of 1, 4-hexadiene. In contrast, the generally supported Rh nanoparticle catalyst (Rh/CHA) showed a low 2-hexene selectivity of 37.2% under identical reaction conditions. Considering that Rh@CHA and Rh/CHA comprise the same CHA zeolite crystals and have similar Rh nanoparticle sizes, the remarkably high selectivity of Rh@CHA is assigned to the steric adsorption of dienes on the Rh surface controlled by the micropores of the CHA zeolite. This work demonstrates that a zeolite-fixed metal core-shell structure is a powerful tool for developing efficient catalysts to be used in diene hydrogenation.
展望
钯基纳米材料电化学还原二氧化碳研究进展
周远, 韩娜, 李彦光
2020, 36(9): 2001041-0  doi: 10.3866/PKU.WHXB202001041
[摘要]  (19) [PDF 2785KB] (0)
摘要:
电化学二氧化碳还原是利用电能驱动将CO2高效转化为小分子碳基燃料的新方法,被认为是目前最具应用潜力的碳资源转化技术之一。然而,CO2还原反应仍面临着诸多挑战,如反应过电位高,产物选择性低以及析氢反应的竞争等。因此,开发高效的电催化剂是发展CO2还原技术的核心关键。近年来,Pd基材料在CO2还原反应中表现出独特的催化性能优势:它不仅可以在接近平衡电位下高选择性地还原CO2生成甲酸/甲酸盐,还能够在一定的负电位区间高效地还原CO2生成CO。尽管如此,Pd基材料目前仍存在着成本较高、活性不理想以及稳定性差等问题,严重制约了其进一步应用与发展。对此,本文首先简单介绍了CO2RR的基本原理,并综述了近年来Pd基催化剂电还原CO2的应用研究及发展现状。重点探讨了尺寸效应、形貌效应、合金效应、核壳效应及载体效应等对Pd基催化剂性能的影响。最后针对这类材料的问题挑战及其未来发展方向进行了探讨与展望。
专访
功能纳米材料研究进展—唐智勇研究员及其团队专访
《物理化学学报》编辑部
2020, 36(9): 2003059-0  doi: 10.3866/PKU.WHXB202003059
[摘要]  (26) [PDF 337KB] (2)
摘要:
亮点
液滴的动态行为控制
刘鸣华
2020, 36(9): 2003072-0  doi: 10.3866/PKU.WHXB202003072
[摘要]  (17) [PDF 522KB] (1)
摘要:
水滑石基材料在长波长光催化CO2还原中的应用
吴骊珠
2020, 36(9): 2004005-0  doi: 10.3866/PKU.WHXB202004005
[摘要]  (16) [PDF 814KB] (1)
摘要:
稀土Er单原子促进光催化CO2还原反应
俞书宏
2020, 36(9): 2004010-0  doi: 10.3866/PKU.WHXB202004010
[摘要]  (20) [PDF 568KB] (0)
摘要:
用于膜科学技术创新的液体门控的动态界面设计
褚良银
2020, 36(9): 2004012-0  doi: 10.3866/PKU.WHXB202004012
[摘要]  (20) [PDF 718KB] (0)
摘要:
以ε-Keggin-Fe13离子为中心的高核稀土-铁氧簇合物
陈小明
2020, 36(9): 2004030-0  doi: 10.3866/PKU.WHXB202004030
[摘要]  (15) [PDF 1092KB] (0)
摘要:
单分散无机超粒子在生物成像分析中的应用
田阳
2020, 36(9): 2004047-0  doi: 10.3866/PKU.WHXB202004047
[摘要]  (17) [PDF 576KB] (0)
摘要:
前言
精准纳米合成
唐智勇
2020, 36(9): 2004050-0  doi: 10.3866/PKU.WHXB202004050
[摘要]  (27) [PDF 374KB] (0)
摘要:

论文
空气下光诱导有机金属卤化钙钛矿薄膜的降解机理
葛杨, 牟许霖, 卢岳, 隋曼龄
2020, 36(8): 1905039-0  doi: 10.3866/PKU.WHXB201905039
[摘要]  (29) [HTML全文] (29) [PDF 3280KB] (29)
摘要:
近几年来钙钛矿材料作为新兴光伏材料取得了巨大的发展进步,但有机无机杂化钙钛矿较差的环境稳定性限制了它的大规模应用。因此深入研究钙钛矿材料的降解机制有助于开发更稳定的钙钛矿光伏器件。本文基于透射电子显微学的微观形貌观察、晶体结构及元素成分表征,详细研究了杂化钙钛矿CH3NH3PbI3薄膜在光照以及空气共同作用下的降解机理。研究发现,光诱导下CH3NH3PbI3薄膜会与空气中的氧气发生交互作用,同时生成六方晶态PbI2甚至氧化为非晶态化合物PbI2−2xOx (0.4 < x < 0.6),而其衰减位点主要存在于薄膜与空气接触的表面。降解过程中,由于存在着挥发性分解产物(I2,CH3NH2)的大量丢失,薄膜的表面会产生许多小孔洞,继而形成一种蜂窝状的介孔衰竭通道。而这种衰竭方式主要与光照下钙钛矿中光生电子与氧气结合形成超氧根自由基(O2•−)有关,该基团诱导了CH3NH3PbI3向PbI2和非晶氧化态的转变。本文揭示了空气中光照诱导钙钛矿薄膜的降解机理,这将为未来设计和优化更稳定的钙钛矿太阳能电池提供全面的实验数据与理论支持。
多孔双金属氧化物/碳复合光催化剂对四环素的高效光催化降解
王艺蒙, 张申平, 葛宇, 王臣辉, 胡军, 刘洪来
2020, 36(8): 1905083-0  doi: 10.3866/PKU.WHXB201905083
[摘要]  (22) [HTML全文] (22) [PDF 4342KB] (22)
摘要:
本工作以金属有机框架材料UiO-67为载体,通过原位水解负载TiO2,经焙烧后得到系列ZrxTi/C光催化剂。我们以四环素为典型抗生素在300 W氙灯光源下进行光降解研究,Zr0.3Ti/C复合催化剂表现出优异的光催化效率,对于10 mg·L-1四环素溶液,30 min可以降解98%。光降解速率常数分别是TiO2、纯UiO-67焙烧产物Zr-O-C的16倍和3.7倍。这得益于Zr0.3Ti/C较大的比表面积,对四环素具有优异的吸附性能;同时具有能级匹配的Zr-O-C/TiO2异质结构和高导电性碳材料共掺,有效提高了电子-空穴对的分离与迁移;机理研究表明光照下产生的超氧自由基(O2•-)、羟基自由基(•OH)以及少量的空穴(h+),共同促进了光催化降解四环素。本研究基于吸附和光催化协同作用原理,所提出的高比表面积、双金属活性的复合光催化材料的制备方法,对抗生素等环境污染物光降解治理方面有一定的指导作用。
温度对乙醇电催化氧化的影响
涂昆芳, 李广, 姜艳霞
2020, 36(8): 1906026-0  doi: 10.3866/PKU.WHXB201906026
[摘要]  (21) [HTML全文] (21) [PDF 2526KB] (21)
摘要:
升高温度可以提高反应速率和增加物质的输运,因此通过不同温度下反应机理的研究可以深入理解电催化过程,对催化剂的设计具有指导意义。本工作初步建立了变温原位红外测定方法。采用温控电极,用电势测温法进行温度的校准,实验得出控温仪器加热温度Th与电极表面温度TS的关系为TS = 0.57Th + 7.71 (30 ℃ < Th≤ 50 ℃);TS = 0.62Th + 5.12 (50 ℃ < Th ≤ 80 ℃),误差分析最大温差为1 ℃。利用该方法我们研究了商业Pt/C催化剂在不同温度下乙醇的电氧化过程。从循环伏安图可以明显看到随着温度的升高整体氧化电流增大,起始电位、峰电位均负移,说明热活化使得氧化反应更容易进行;第一个峰电流与第二个峰电流的比值用于定性评估CO2的选择性,对比25 ℃,商业Pt/C催化剂在65 ℃下第一峰提高30%,说明高温有利于C―C键的断裂。对比25 ℃的原位红外谱图,我们发现35 ℃及50 ℃下商业Pt/C催化剂上CO2产物的起始电位负移200 mV,说明高温下,Pt/C催化剂能在更低的电位提供含氧物种;而CH3CHO、CH3COOH起始电位不随温度变化。用CO2与CH3COOH的积分面积比来评估CO2选择性,发现高温低电位其选择性最高,说明高温低电位有利于乙醇完全氧化生成CO2,而高温高电位下表面吸附含氧物种占据了活性位,阻碍C―C键断裂。
单原子分散的Au/Cu(111)表面合金的表面结构与吸附性质
王文元, 张杰夫, 李喆, 邵翔
2020, 36(8): 1911035-0  doi: 10.3866/PKU.WHXB201911035
[摘要]  (25) [HTML全文] (25) [PDF 3321KB] (25)
摘要:
Au-Cu双金属合金纳米颗粒对包括CO氧化和CO2还原等在内的多个反应有较好的催化活性,然而关于其表面性质的研究却相当匮乏。在此工作中,我们通过对低覆盖度的Au/Cu(111)和Cu/Au(111)双金属薄膜退火,制备出了单原子级分散的Au/Cu(111)和Cu/Au(111)合金化表面,并利用高分辨扫描隧道显微镜(STM)和扫描隧道谱(STS)进一步研究了掺杂原子的电子性质及其对CO吸附行为的影响。研究发现,分散在Cu(111)表面的表层和次表层Au单原子在STM上表现出不同衬度。在−0.5 eV附近,前者表现出相较于Cu(111)明显增强的电子态密度,而后者则明显减弱。吸附实验表明表层Au单原子对CO的吸附能力并没有得到增强,甚至会减弱其周围Cu原子的吸附能力。与Au在Cu(111)表面较好的分散相反,Cu原子倾向于钻入Au(111)的次表层,并且形成多原子聚集体。且Cu原子受Au(111)衬底吸电子作用的影响,其对CO的吸附能力明显减弱。这个研究结果揭示了合金表面的微观结构与性质的关联,为进一步阐明Au-Cu双金属催化剂的表面反应机理提供参考。
Article
Catalytic Oxidation of Toluene Over Potassium Modified Mn/Ce0.65Zr0.35O2 Catalyst
Xiaoxiao Lai, Jie Feng, Xiaoying Zhou, Zhongyan Hou, Tao Lin, Yaoqiang Chen
2020, 36(8): 1905047-0  doi: 10.3866/PKU.WHXB201905047
[摘要]  (23) [HTML全文] (23) [PDF 1141KB] (23)
摘要:
Volatile organic compounds (VOCs) are both harmful to human health and the environment; however, catalytic combustion offers a promising method for VOC purification because of its high efficiency without secondary pollution. Although manganese-based catalysts have been well studied for VOC catalytic oxidation, their catalytic activity at low temperature must be improved. Alkali metals as promoters have the potential to modulate the electronic and structural properties of the catalysts, improving their catalytic activity. Herein, a Ce0.65Zr0.35O2 support was prepared by co-precipitation and MnOx/Ce0.65Zr0.35O2 catalysts were obtained through the incipient-wetness impregnation method. The catalytic properties of K-modified MnOx/Ce0.65Zr0.35O2 for toluene oxidation with different molar ratios of K/Mn were investigated. In addition, the catalysts were characterized by XRD, UV/visible Raman, Hydrogen temperature program reduction (H2-TPR), Oxygen temperature programmed desorption (O2-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance FTIR spectroscopy (DRIFTS) experiments. The results showed that alkali metal doping with K significantly improved the catalytic activity. In particular, when the molar ratio of K/Mn was 0.2, the monolith catalyst Mn/Ce0.65Zr0.35O2-K-0.2 exhibited the best performance with the lowest complete conversion temperature T90 of 242 ℃ at a GHSV of 12000 h−1. The XRD results suggested that MnOx was uniformly distributed on the surface of the catalyst and that Mn4+ partially reduced to Mn3+ on the addition of K. The Raman spectrum demonstrated that with increasing K content, both the β- and α-MnO2 phases coexisted on the Mn/Ce0.65Zr0.35O2-K-0.2 catalyst, increasing the number of surface defect sites. The H2-TPR experiment results confirmed that Mn/Ce0.65Zr0.35O2-K-0.2 exhibited the lowest reduction temperature and good reducibility. From the O2-TPD experiments, it was clear that Mn/Ce0.65Zr0.35O2-K-0.2 contained the most surface adsorbed oxygen species and excellent lattice oxygen mobility, which benefitted the toluene oxidation activity. In addition, the XPS results suggested that the content of surface adsorbed oxygen species of the Mn/Ce0.65Zr0.35O2-K-0.2 catalyst was the highest among all the tested samples. In addition, toluene-TPSR in N2 as measured by in situ DRIFTs analysis demonstrated that available lattice oxygen was present in the Mn/Ce0.65Zr0.35O2-K-0.2 catalyst. Therefore, the Mn/Ce0.65Zr0.35O2-K-0.2 catalyst exhibited the best redox properties and oxygen mobility of the prepared samples and showed excellent activity toward toluene oxidation. Therefore, it was concluded that the addition of an appropriate amount of K improved the redox performance of the catalyst and increased the number of surface defect sites and mobility of the lattice oxygen of the catalyst as well as the concentration of the surface active oxygen species, thereby significantly improving catalytic ability.
Preparation and Characterization of Pt@Au/Al2O3 Core-Shell Nanoparticles for Toluene Oxidation Reaction
Chao Zhang, Sihan Li, Chenliang Wu, Xiaoqing Li, Xinhuan Yan
2020, 36(8): 1907057-0  doi: 10.3866/PKU.WHXB201907057
[摘要]  (26) [HTML全文] (26) [PDF 2461KB] (26)
摘要:
Customizing core-shell nanostructures is considered to be an efficient approach to improve the catalytic activity of metal nanoparticles. Various physiochemical and green methods have been developed for the synthesis of core-shell structures. In this study, a novel liquid-phase hydrogen reduction method was employed to form core-shell Pt@Au nanoparticles with intimate contact between the Pt and Au particles, without the use of any protective or structure-directing agents. The Pt@Au core-shell nanoparticles were prepared by depositing Au metal onto the Pt core; AuCl4− was reduced to Au(0) by H2 in the presence of Pt nanoparticles. The obtained Pt@Au core-shell structured nanoparticles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution TEM, fast Fourier transform, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and H2-temperature programmed reduction (H2-TPR) analyses. The EDX mapping results for the nanoparticles, as obtained from their scanning transmission electron microscopy images in the high-angle annular dark-field mode, revealed a Pt core with Au particles grown on its surface. Fourier transform measurements were carried out on the high-resolution structure to characterize the Pt@Au nanoparticles. The lattice plane at the center of the nanoparticles corresponded to Pt, while the edge of the particles corresponded to Au. With an increase in the Au content, the intensity of the peak corresponding to Pt in the FTIR spectrum decreased slowly, indicating that the Pt nanoparticles were surrounded by Au nanoparticles, and thus confirming the core-shell structure of the nanoparticles. The XRD results showed that the peak corresponding to Pt shifted gradually toward the Au peak with an increase in the Au content, indicating that the Au particles grew on the Pt seeds; this trend was consistent with the FTIR results. Hence, it can be stated that the Pt@Au core-shell structure was successfully prepared using the liquid-phase hydrogen reduction method. The catalytic activity of the nanoparticles for the oxidation of toluene was evaluated using a fixed-bed reactor under atmospheric pressure. The XPS and H2-TPR results showed that the Pt1@Au1/Al2O3 catalyst had the best toluene oxidation activity owing to its lowest reduction temperature, lowest Au 4d & 4f and Pt 4d & 4f binding energies, and highest Au0/Auδ+ and Pt0/Pt2+ proportions. The Pt1@Au2Al2O3 catalyst showed high stability under dry and humid conditions. The good catalytic performance and high selectivity of Pt@Au/Al2O3 for toluene oxidation could be attributed to the high concentration of adsorbed oxygen species, good low-temperature reducibility, and strong interaction.
亮点
由二氧化碳合成长链羧酸
刘志敏
2020, 36(8): 1912045-0  doi: 10.3866/PKU.WHXB201912045
[摘要]  (23) [HTML全文] (23) [PDF 279KB] (23)
摘要:
对结冰过程中临界冰核的探测
刘忠范
2020, 36(8): 2001013-0  doi: 10.3866/PKU.WHXB202001013
[摘要]  (21) [HTML全文] (21) [PDF 373KB] (21)
摘要:
“一箭双雕”:同时赋予金纳米团簇催化活性和水溶性
刘鸣华
2020, 36(8): 2001014-0  doi: 10.3866/PKU.WHXB202001014
[摘要]  (34) [HTML全文] (34) [PDF 544KB] (34)
摘要:
水/固界面的氢键动力学
江颖
2020, 36(8): 2001023-0  doi: 10.3866/PKU.WHXB202001023
[摘要]  (30) [HTML全文] (30) [PDF 770KB] (30)
摘要:
非金属元素催化活性的调控机理
杨金龙
2020, 36(8): 2001026-0  doi: 10.3866/PKU.WHXB202001026
[摘要]  (23) [HTML全文] (23) [PDF 0KB] (23)
摘要:
一种利用精确纳米组装结构调控水下产气速率的普适方法
俞书宏
2020, 36(8): 2001028-0  doi: 10.3866/PKU.WHXB202001028
[摘要]  (29) [HTML全文] (29) [PDF 616KB] (29)
摘要:
锌阳极原位固态电解质界面
陈立泉
2020, 36(8): 2001035-0  doi: 10.3866/PKU.WHXB202001035
[摘要]  (26) [HTML全文] (26) [PDF 582KB] (26)
摘要:
可编程DNA胶束
刘鸣华
2020, 36(8): 2001036-0  doi: 10.3866/PKU.WHXB202001036
[摘要]  (23) [HTML全文] (23) [PDF 873KB] (23)
摘要:
单壁碳纳米管的控制生长与生长动力学
杨金龙
2020, 36(8): 2002014-0  doi: 10.3866/PKU.WHXB202002014
[摘要]  (20) [HTML全文] (20) [PDF 528KB] (20)
摘要:
周期性长程有序介孔钯催化剂用于高效甲酸氧化催化
杨金龙
2020, 36(8): 2003010-0  doi: 10.3866/PKU.WHXB202003010
[摘要]  (25) [HTML全文] (25) [PDF 845KB] (25)
摘要:
专访
专访中国理论与计算化学领军人物:2019年新科院士杨金龙
《物理化学学报》编辑部
2020, 36(8): 1912046-0  doi: 10.3866/PKU.WHXB201912046
[摘要]  (37) [HTML全文] (37) [PDF 334KB] (37)
摘要:
特邀述评
建立学术共同体互信的基金评审机制的尝试与思考
戴亚飞, 高飞雪, 王翠霞, 陈拥军
2020, 36(8): 2003034-0  doi: 10.3866/PKU.WHXB202003034
[摘要]  (22) [HTML全文] (22) [PDF 292KB] (22)
摘要:
完善评审机制是国家自然科学基金委新时代基金改革的重要任务之一。为切实落实该项改革任务,建立符合新时代科学基金资助导向的科学、公正、高效的评审机制,基金委化学部努力探索新的学科基金管理模式,尝试了在通信评审阶段由科学家与学科管理人员共同参与项目的分组、指派,共同完成同行评议专家遴选工作的新模式。本文分析了科学家参与同行评议专家遴选工作的利弊,探讨了如何更好的发挥科学家在同行评议专家遴选工作中的作用,建立学术共同体互信的基金评审机制。
科学基金项目会议评审机制刍议
张国俊, 付雪峰, 戴亚飞, 陈拥军
2020, 36(8): 2003051-0  doi: 10.3866/PKU.WHXB202003051
[摘要]  (23) [HTML全文] (23) [PDF 515KB] (23)
摘要:
项目评审是科学基金管理工作的核心。本文梳理分析了目前科学界日益关注的会议评审过程中存在的问题,重新审视会议评审的意义和功能,提出基于“确认-纠偏-择优”原则的会评评审改革建议和措施。
大处着眼,小处入手——基金委化学科学部2019年基金项目会议评审工作的几点尝试和思考
付雪峰, 黄艳, 崔琳, 陈拥军
2020, 36(8): 2004002-0  doi: 10.3866/PKU.WHXB202004002
[摘要]  (41) [HTML全文] (41) [PDF 722KB] (41)
摘要:
国家自然科学基金是我国资助基础研究的主渠道,基金项目的同行评审环节对于自然科学基金资助工作至关重要。本文总结了化学科学部2019年基金项目会议评审工作的一些尝试,以营造良好学术评审环境为着眼点,采用分组会评、规范会评程序、细化会评流程等措施,完善项目会评工作。
浅析基金评审的模糊属性
付雪峰, 戴亚飞, 黄艳, 崔琳, 陈拥军
2020, 36(8): 2004048-0  doi: 10.3866/PKU.WHXB202004048
[摘要]  (18) [HTML全文] (18) [PDF 440KB] (18)
摘要:
同行评议是科学基金项目评审的重要环节。高质量的同行评议是实现基金精准资助的前提和保障。本文以国家自然科学基金通讯评审为例,针对同行评议中出现的评审偏差,探讨了基金评审的模糊属性,提出了通过构建评审结果的模糊集合及一致性函数来解决该问题的可能性,为进一步优化评审结果、实现基金精准资助指出了新方向。
推荐
变温电化学原位红外光谱及其对乙醇电催化氧化研究
申文杰
2020, 36(8): 2004033-0  doi: 10.3866/PKU.WHXB202004033
[摘要]  (18) [HTML全文] (18) [PDF 1351KB] (18)
摘要:

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

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发布时间: 2018-05-02


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发布日期:2009-06-24 浏览: