Co-reporter:Xi-Guang Han;Hui-Zhong He;Tao Xu;Xian-Hua Zhang;Qin Kuang;Xi Zhou;Lan-Sun Zheng
The Journal of Physical Chemistry C January 15, 2009 Volume 113(Issue 2) pp:584-589
Publication Date(Web):2017-2-22
DOI:10.1021/jp808233e
In this paper, we successfully synthesized three kinds of typical ZnO micro/nanocrystallites including flakes, columns, and pyramids by means of different facile wet chemical routes. The growth environment plays a crucial role in the morphologies of these ZnO micro/nanocrystallites. At the same time, we find that physical/chemical properties of these ZnO samples are dependent on their exposed surface, and the order of gas sensing and photocatalytic efficiency of the ZnO crystal planes is (0001) > {101̅0} > {101̅1} and (0001̅). On the basis of structural analyses of various exposed surfaces and related X-ray photoelectron spectroscopy, we deeply discussed the effect of definite surface structures on their gas sensing and photocatalytic properties.
Co-reporter:Jiawei Zhang 张嘉伟;Meishan Chen 陈梅珊;Jiayu Chen 陈佳煜;Huiqi Li 李慧齐
Science China Materials 2017 Volume 60( Issue 8) pp:685-696
Publication Date(Web):08 August 2017
DOI:10.1007/s40843-017-9073-9
The catalytic properties of noble metal nanocrystals can be tuned via engineering their structures. Nanocrystals with fractal structures are fascinating catalysts regarding their large surface area-to-volume ratios, large numbers of edges and corners, which can be tuned simultaneously by their hierarchical ordering. However, it is still a great challenge to control the hierarchical ordering of noble metal fractal nanocrystals and their formation mechanism is not fully understood. Herein, we report a facile solvothermal method for the direct preparation of a unique single-crystal Rh-hyperbranched structure, which consists of hierarchically ultrathin nanoplates with threefold symmetry, large surface area and high density of low-coordinated edge/corner sites. Importantly, the hierarchical ordering can be readily tuned by changing the composition of solvent. In addition, we found the as-prepared single-crystal hyperbranched Rh nanoplates possessed great structure stability, and exhibited better catalytic performance towards both ethanol electrooxidation and hydrogenation of styrene than the commercial Rh black, which can be attributed to the large surface area and high-dentisty of edge/corner sites.贵金属纳米晶的催化性质与其结构密切相关. 比表面积越大、配位不饱和的边角原子密度越高, 贵金属纳米晶在催化反应过程中表现出的性能往往越优异. 相比于常见的具有完整几何形貌的贵金属纳米晶, 具有多重分级结构特征的超支化贵金属纳米晶拥有更大的比表面积以及更丰富的配位不饱和的活性位点, 因此被认为是一种潜在的性能优异的催化剂. 但这种具有多重分级结构特征的超支化贵金属纳米晶无论是在生长机理研究还是可控制备上都还存在巨大的挑战. 本文通过简单的湿化学法成功制备出一种具有多重分级结构特征的超支化Rh纳米薄片. 该产物由三角形纳米片在扩散限制条件下分级生长形成, 整体呈现三次对称性的单晶特征. 研究表明, 该纳米结构不仅具有出色的结构稳定性, 而且其生长级数可通过反应溶剂比例的简单调节进行调控, 从而实现Rh纳米薄片比表面积和位于边/角活性位点的原子比例的调控. 由于拥有更大的比表面积以及更为丰富的配位不饱和的活性位点, 这种具有多重分级结构的超支化Rh纳米薄片在乙醇电催化氧化和苯乙烯催化加氢催化反应中展现出了比目前主流商业催化剂Rh黑更为优异的催化活性.
Co-reporter:Qiaoli Chen, Guifen Du, Yongdi Dong, Zhenming Cao, ... Lansun Zheng
Science Bulletin 2017 Volume 62, Issue 20(Volume 62, Issue 20) pp:
Publication Date(Web):30 October 2017
DOI:10.1016/j.scib.2017.09.008
In wet chemical syntheses of noble metal nanocrystals, surfactants play crucial roles in regulating their morphology. To date, more attention has been paid to the effect of the surfactant on the surface energy of crystal facets, while less attention has been paid to its effect on the growth kinetics. In this paper, using the growth of Au-Pd alloy nanocrystals as an example, we demonstrate that different concentration of surfactant hexadecyltrimethyl ammonium chloride (CTAC) may cause the different packing density of CTA+ bilayers on different sites (face, edge or vertex) of crystallite surface, which would change the crystal growth kinetics and result in preferential crystal growth along the edge or vertex of crystallites. The unique shape evolution from trisoctahedron to excavated rhombic dodecahedron and multipod structure for Au-Pd alloy nanocrystals was successfully achieved by simply adjusting the concentration of CTAC. These results help to understand the effect of surfactants on the shape evolution of nanocrystals and open up avenues to the rational synthesis of nanocrystals with the thermodynamically unfavorable morphologies.Unique shape evolution from trisoctahedron to excavated rhombic dodecahedron and multipod structure for Au-Pd alloys are successfully achieved by simply adjusting the concentration of surfactant.Download high-res image (68KB)Download full-size image
Co-reporter:Xue Wang;Jiayu Chen;Jianxin Zeng;Qiuxiang Wang;Zejun Li;Ruixuan Qin;Changzheng Wu;Zhaoxiong Xie;Lansun Zheng
Nanoscale (2009-Present) 2017 vol. 9(Issue 20) pp:6643-6648
Publication Date(Web):2017/05/25
DOI:10.1039/C6NR09707C
We report a photochemical synthesis of Pd/CeO2 catalysts with atomically dispersed Pd. Compared to atomically dispersed Pd/CeO2 with a cubic CeO2 support (Pd/CeO2-CP), atomically dispersed Pd/CeO2 with a truncated octahedral CeO2 support (Pd/CeO2-TOP) exhibited higher activity and selectivity, owing to the synergy between Pd atoms and the (111) surface of CeO2. When compared to Pd/CeO2 with Pd clusters and nanoparticles via chemical reduction, Pd/CeO2-TOP showed excellent activity with an enhancement factor of 324 in CO oxidation, as well as an activity enhancement by a factor of 344 in selective oxidation of benzyl alcohol.
Co-reporter:Qiaoli Chen, Zhenming Cao, Guifen Du, Qin Kuang, Jin Huang, Zhaoxiong Xie, Lansun Zheng
Nano Energy 2017 Volume 39(Volume 39) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.nanoen.2017.07.041
•Excavated octahedral PtCo NCs with specific facets and large surface area were synthesized.•The surfactant and growth kinetics affects the composition and morphology of PtCo NCs.•Excavated PtCo NCs showed superior performance as multifunctional electrocatalysts.Pt-Co alloy is thought to be the best potential catalyst toward many electrocatalytic energy conversion reactions among various bimetallic alloys. To optimize the performance and reduce the usage of noble metal Pt, both the mass and surface contribution should be considered, which requires Pt-Co alloy nanocrystals (NCs) to possess large surface area and expose specific facets. Unfortunately, these requirements can hardly be met simultaneously for the NCs with normal convex polyhedral shapes. In this work, a simple cetyltrimethylammonium bromide-assisted method is proposed to controllably synthesize Pt-Co alloy NCs with a unique excavated octahedral shape. The excavated octahedral Pt-Co alloy NCs is intrinsically built with mutually perpendicular interlaced ultrathin PtCo nanosheets bound with {100} facets that are not the thermodynamically most stable for face-centered cubic metals. The electrochemically surface area of the unique excavated octahedral PtCo alloy NCs is determined to be 23.3 m2 g−1Pt, which is significantly larger than that of the normal octahedral Pt2Co alloy NCs with the same size (11.4 m2 g−1Pt). Owing to the combination of large surface area and high active {100} facets, the excavated octahedral PtCo NCs display extraordinary catalytic activity and durability towards hydrogen evolution reaction in alkaline environment. Strikingly, the overpotential of excavated PtCo NCs at the current density of 20 mA cm−2 is as low as 76.2 mV, which is much lower than that for the {111} faceted Pt2Co NCs (83.9 mV) and the commercial Pt/C (107 mV), respectively. Besides, the excavated octahedral PtCo NCs also show significantly enhanced electrocatalytic performances towards methanol oxidation reaction and oxygen reduction reaction when both considering the mass and surface contribution.Download high-res image (214KB)Download full-size image
Co-reporter:Jiangtao Wu;Zuzhen Liao;Ting Sun;Lun-Wei Su;Jian Bi;Guangyin Fan;Daojiang Gao;Zhaoxiong Xie;Zuo-Guang Ye
Journal of Materials Chemistry C 2017 vol. 5(Issue 16) pp:4063-4067
Publication Date(Web):2017/04/20
DOI:10.1039/C7TC00512A
In ferromagnets, the magnetic moment can generally be reversed by applying a sufficiently high external magnetic field of opposite polarity. Temperature, on the other hand, is usually known to affect only the magnitude of a magnetic moment, rather than its sign or polarity (most magnets exhibit a monotonic increase in magnetization upon cooling below their magnetic phase transition temperature). As a result, temperature-induced magnetization reversal (i.e. magnetic pole inversion) remains a very rare phenomenon which lacks proper understanding and explanation because of the extreme difficulties encountered in controlling the thermodynamics of magnetization of classical metal or metal oxide magnets. Herein, we report an unusual magnetic pole inversion behaviour in multiferroic (1 − x)BiFeO3–xDyFeO3 solid solution (alloy), which can be tuned by varying the concentration of the magnetic ion Dy3+ in the solid solution. It is found that the temperature-induced magnetic pole inversion occurs in a wide composition range (x = 0.14–0.90). Moreover, for the first time in any ferrites, multiple magnetic pole inversions are observed in the solid solution compounds of high Dy3+-concentrations. Our results may provide a better understanding of the temperature- and composition-induced magnetic pole inversion and related phenomena and point to new potential applications for magnetic and multiferroic materials.
Co-reporter:Qiaoli Chen, Yanyan Jia, Shuifen Xie and Zhaoxiong Xie
Chemical Society Reviews 2016 vol. 45(Issue 11) pp:3207-3220
Publication Date(Web):18 Apr 2016
DOI:10.1039/C6CS00039H
Precise engineering of noble-metal nanocrystals (NCs) is not only an important fundamental research topic, but also has great realistic significance in improving their performances required by the poor reserve and high cost of noble metals. Well-faceted noble-metal NCs with nonconvex polyhedral shapes could be promising candidates to optimize their performance and thus minimize their usage, as they may integrate a well-defined surface structure and a large surface area together, enabling them to have outstanding performance and high efficiency of atomic utilization. Moreover, undesirable aggregation and ripening phenomena could be avoided. This review provides a comprehensive summary of the unique characteristics and corresponding models of well-faceted nonconvex polyhedral noble-metal NCs by classifying the cases into four distinct types, namely the concave polyhedral structure, excavated polyhedral structure, branched structure and nanocage structure, respectively. Due to the complexity of nonconvex morphologies and the thermodynamic antipathy for the growth of nonconvex shaped NCs, we firstly demonstrate the structure characterization and synthetic methodology in detail. Subsequently, typical applications in electrocatalysis and plasmonic fields are presented to demonstrate the unique surface and morphological effects generated from the well-faceted nonconvex NCs. To promote further development in this field, the perspectives and challenges concerning well-faceted noble-metal NCs with nonconvex shapes are put forward in the end.
Co-reporter:Jiawei Zhang, Qin Kuang, Yaqi Jiang, Zhaoxiong Xie
Nano Today 2016 Volume 11(Issue 5) pp:661-677
Publication Date(Web):October 2016
DOI:10.1016/j.nantod.2016.08.012
•Overview of synthesis of noble metal nanocrystals with high-energy facets.•Thermodynamic/kinetic roles of capping agents in formation of high-energy facets.•Supersaturation-controlled crystal growth explains contradictory results.•Surface structure-dependent activity and selectivity of noble metal catalysts.Tailoring of the surface structure of noble metal nanocrystals is a hot research topic because of the fascinating surface structure-dependent properties in enormous applications, such as heterogeneous catalysis. Due to high densities of atomic steps and kinks and their abundance of unsaturated coordination sites, noble metal NCs with high-energy surfaces often exhibit superior performances compared to those with low-energy surface structures. A complete understanding of the growth mechanisms of noble-metal NCs with high-energy surface structures would enable the rational design of noble metal NCs with optimized performances for specific applications. In this review, we concentrate on the growth mechanisms of noble-metal NCs with high-energy facets by summarizing the state-of-the-art progress in the surface structure-controlled synthesis of noble metal NCs with high-energy facets. By carefully considering both the thermodynamic and kinetic factors that affect the surface structures, we intentionally classify different approaches into four categories (i.e., surface-regulating-agent assisted strategies, supersaturation controlled strategies, electrochemical methods, and template directed methods), and insights into the respective growth mechanisms are demonstrated by representative examples. Especially, we highlight the role of supersaturation in the formation of the high-energy surface, which successfully explained apparent contradictory results when only taking the “capping” effect into consideration. Then several typical examples are given to demonstrate the versatility of the high-energy facets in improving both catalytic activity and selectivity. In addition, the stability of high-energy facets is also discussed. Finally, the remaining challenges and perspectives for future directions are given for this promising field of research. We hope the deep and comprehensive understanding the growth mechanism of the nanocrystals would help to guild the rational design of functional nanomaterials with desired outstanding properties.
Co-reporter:Qiaoli Chen, Yanyan Jia, Wei Shen, Shuifen Xie, Yanan Yang, Zhenming Cao, Zhaoxiong Xie and Lansun Zheng
Nanoscale 2015 vol. 7(Issue 24) pp:10728-10734
Publication Date(Web):18 May 2015
DOI:10.1039/C5NR02017D
Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective strategy to synthesize Au nanocrystals with excavated trioctahedral structure in one step. Due to the novel feature of the excavated structure and exposed high energy {110} facets, excavated trioctahedral Au NCs exhibited optical extinction at the near-infrared region and showed high catalytic activity towards the reduction of p-nitrophenol. Moreover, the synthetic strategy can be extended to the synthesis of excavated Au–Pd alloys.
Co-reporter:Lei Zhang, Qiaoli Chen, Zhiyuan Jiang, Zhaoxiong Xie and Lansun Zheng
CrystEngComm 2015 vol. 17(Issue 29) pp:5556-5561
Publication Date(Web):29 May 2015
DOI:10.1039/C5CE00766F
The syntheses of noble metal nanocrystals (NCs) with systematic shape evolution have received extensive attention in the research on nanomaterials. The introduction of foreign metal ions was one of the most effective ways to control the shape of the noble metals. However, most of the reports on the shape influence of foreign metal ions have focused on Ag+. Herein, we systematically investigated the influence of Cu2+ on the structure evolution of Au NCs by forming an underpotential deposition atom layer on the metal surface. The growth rate of atoms on high-index surfaces became more rapid than that on low-index facets, which caused the NCs to evolve from trioctahedral to cubic and octahedral structures. In addition, by regulating the given amount of Cu, Au–Pd alloy NCs with different morphologies can also be prepared. Furthermore, we found that the as-prepared HOH and cubic Au–Pd alloy NCs exhibited excellent performance in formic acid electro-oxidation in comparison with Pd black.
Co-reporter:Jiangtao Wu, Nan Li, Jun Xu, Shuang Zhou, Yaqi Jiang, Zhaoxiong Xie
Journal of Alloys and Compounds 2015 Volume 634() pp:142-147
Publication Date(Web):15 June 2015
DOI:10.1016/j.jallcom.2015.01.283
•Single phase (1 − x)BiFeO3–xLaMnO3 (x = 0–1) solid solution were synthesized.•The phase transitions were investigated by tuning composition and temperature.•Phase diagram was constructed according to the results of XRD for the first time.•The solid solution possess polarity feature at a wide concentration of x ⩽ 0.25.•The magnetization of solid solution can be greatly enhanced when x > 0.08.In this paper, we report the syntheses of (1 − x)BiFeO3–xLaMnO3 solid solution (x = 0–1) by an improved sol–gel method. With careful characterization of crystal structures of the as-prepared products and the phase transition as a function of temperature, the phase diagram of (1 − x)BiFeO3–xLaMnO3 solid solution has been determined. With the increasing of x value, the crystal structure of the samples transforms from rhombohedral R3c (x ⩽ 0.13) to tetragonal P4mm (0.14 ⩽ x ⩽ 0.25), cubic Pm3¯m (0.26 ⩽ x ⩽ 0.78), and finally to rhombohedral R3¯c (0.80 ⩽ x ⩽ 1.00). In situ high temperature X-ray powder diffraction (HTXRD) studies reveal that the phase transformations of rhombohedral R3c to orthorhombic Pbnm and tetragonal P4mm to orthorhombic Pbnm occur at 600–750 °C and 580–700 °C, respectively. The phase structures of cubic Pm3¯m and rhombohedral R3¯c keep unchanged at temperature below 880 °C. However, a second-order-like phase transition was observed at higher temperature because of the change of thermo expansion coefficient. The complete phase diagram was then drawn based on those experimental results. It can be found clearly from the phase diagram that the as-prepared (1 − x)BiFeO3–xLaMnO3 (x = 0–1) solid solutions provided more options to tune the magnetism and multiferroism, as the crystal structures possess polarity feature at a wide doping concentration of LaMnO3 (x ⩽ 0.25). We then selectively studied the magnetic properties of possible multiferroic phases, i.e. R3c and P4mm phases. The results revealed that the magnetic property can be greatly enhanced when doping fraction of LaMnO3 is more than 0.08 (x > 0.08).
Co-reporter:Qiuxiang Wang, Qin kuang, Kunshui Wang, Xue Wang and Zhaoxiong Xie
RSC Advances 2015 vol. 5(Issue 75) pp:61421-61425
Publication Date(Web):10 Jul 2015
DOI:10.1039/C5RA08988C
Hollow nanomaterials have attracted intense attention due to their special structures and potential applications in many fields. In this paper, we report a surfactant free synthesis of hollow Cu2O nanocubes by reducing Cu2+ precursors using Cl− ions as the morphology regulator at room temperature. It is found that in the presence of Cl− ions, hollow Cu2O nanocubes can be easily synthesized by directly reducing Cu2+ precursors with ascorbic acid. Through well-designed experiments, we propose that, in this surfactant free synthetic route, the formation of hollow Cu2O nanocubes results from a reaction activated Kirkendall diffusion process of cubic CuCl intermediates, which are formed in the reaction process and act as self-sacrificial templates. The amounts of Cl− ions and NaOH are two key factors to determine whether hollow Cu2O nanocubes are formed or not.
Co-reporter:Wei Chen, Qin Kuang, Qiuxiang Wang and Zhaoxiong Xie
RSC Advances 2015 vol. 5(Issue 26) pp:20396-20409
Publication Date(Web):05 Feb 2015
DOI:10.1039/C5RA00344J
Anatase titanium dioxide (A-TiO2) is one of the most important functional materials and is widely used in various energy- and environmental related applications. Over the past decade, great efforts have been devoted to surface engineering of A-TiO2 crystals at the atomic level so as to fundamentally understand the relationship between the surface structure and their performance in practical applications. In this review, we briefly summarize recent important achievements on the control of specific surface structures of A-TiO2 crystals, focusing on facets with high surface energy (such as {001}, {100}, {101}) and their combinations. In addition, fascinating performances of A-TiO2 crystals enhanced by these high energy surfaces are examined and discussed through the perspectives of synergistic effects of different facets and surface adsorbates, with additional insights related to some contradictory results. Finally, we offer a summary and some perspectives on current challenges and promising directions in this emerging field. We believe that a comprehensive understanding of surface engineering of A-TiO2 crystals with regard to high energy facets will in the long term help us to rationally design functional nanomaterials with desired performances.
Co-reporter:Yanyan Jia, Jingyun Su, Zhibin Chen, Kai Tan, Qiaoli Chen, Zhenming Cao, Yaqi Jiang, Zhaoxiong Xie and Lansun Zheng
RSC Advances 2015 vol. 5(Issue 23) pp:18153-18158
Publication Date(Web):23 Jan 2015
DOI:10.1039/C4RA15673K
Bimetallic alloy nanocrystals (NCs) have received great attention because their physical and chemical properties greatly depend on their composition and structure. However, simultaneous control of the composition and surface structure (or morphology) of metal alloy NCs is challenging due to differences in standard redox potential (SRP). According to our previous research, well-shaped and composition-tunable Pt–Cu alloy NCs can be controlled in mild reduction conditions. However, the content of Cu in the as-prepared Pt–Cu alloy NCs cannot exceed 50% using N,N-dimethylformamide (DMF) as the weak reductant. In this paper, we reported a successful synthesis of the octahedral Pt–Cu bimetallic alloy NCs with a molar ratio of Cu ranging from 50% to 75% via introducing a slightly stronger reductant (n-butylalcohol) to improve the reducing ability and tune the sequential reaction kinetics. It is found that n-butylalcohol can solely reduce the Cu precursor to metallic copper. The UPD-like process ensures the formation of the Pt–Cu alloy due to the strong binding energy between Cu atoms and the Pt crystal surface. Owing to the successful control of Cu, the content in Pt–Cu alloy increased from 50% to 75%, and the relationship between the composition and the properties of the electro-catalytic oxidation of formic acid were further investigated. The results reveal that the electro-catalytic performance of the Pt–Cu alloy is enhanced along with Cu content, and that PtCu3 exhibits excellent catalytic activity and anti-poisoning ability.
Co-reporter:Yanyan Jia;Zhenming Cao;Qiaoli Chen;Yaqi Jiang;Zhaoxiong Xie
Science Bulletin 2015 Volume 60( Issue 11) pp:1002-1008
Publication Date(Web):2015 June
DOI:10.1007/s11434-015-0781-4
In this paper, we reported a solvothermal method for the synthesis of octahedral Pt–Cu bimetallic alloy nanocrystals (NCs) with tunable composition. Inspired by the result from our previous exploration on octahedral Pt–Cu alloy NCs that Cu contents can be tuned from 10 % to 50 %, we further tuned the Cu portion from 50 % to 75 % by simply introducing n-butylamine in the reaction system. It is believed that n-butylamine plays a key role in breaking through a thermodynamic constraint in the formation of Pt–Cu alloy nanocrystals (NCs). The synergistic effect of underpotential deposition-like Cu reduction and the different complexion abilities of amine group of n-butylamine with two metal species effectively tuned the reduction kinetics, by which each reduced Pt atom is able to catalyze reduction of more Cu atoms and be fully covered with 12 Cu atoms in the Pt–Cu alloy crystal, while Cu precursor is not able to be reduced solely and bind solely with Cu atoms, resulting in the successful tuning of Cu composition from 50 % to 75 %. In addition, we investigated the electro-catalytic activity of Pt–Cu bimetallic alloy NCs with different composition in electro-oxidation of methanol. The as-prepared PtCu3 NCs exhibit excellent electro-catalytic performance and stability in comparison with commercial Pt black and other compositional Pt–Cu alloy NCs.由于不同金属之间氧化还原电势、原子半径和电负性的不同,设计和制备形貌和合金成分可控双金属合金纳米晶仍具挑战。在金属欠电位沉积(UPD)诱导Cu的还原合成了Cu比例可达50 %的八面体Pt-Cu合金纳米晶的基础上,引入正丁胺,通过其与金属的配位作用调节了Pt和Cu前驱物的还原速度,进一步将Cu的比例提高到75 %。与UPD单原子层沉积类似,在该反应中每个被还原的Pt原子均有能力催化Cu原子的还原并键合最多12个Cu原子(密堆积结构),而铜前驱物不能在Cu原子表面上直接还原,使得纳米晶体中Cu的比例最高达到75 %。此外,性能研究表明PtCu3纳米晶体表现出最高的电催化活性和稳定性。.
Co-reporter:Wei Chen;Qin Kuang;Zhaoxiong Xie
Science China Materials 2015 Volume 58( Issue 4) pp:281-288
Publication Date(Web):2015 April
DOI:10.1007/s40843-015-0041-6
Surface structure control of functional nano-/micro-crystallites has attracted great attention because many important physicochemical properties depend on their surface. Guided by the supersaturation-dependent surface structure evolution strategy we proposed recently, NaTaO3 submicrometer crystals with morphologies of cubes, corner truncated cubes, edge and corner truncated cubes, and quasi-spheres can be synthesized by changing the volume ratio of ethylene glycol to water and the amount of NaOH in the composite solvent. Under low supersaturation condition, NaTaO3 cubic crystals with low energy {100} facets were obtained. As the supersaturation increases, the corners and edges of NaTaO3 cubic crystals, which possess higher surface energy, were gradually truncated. Surprisingly, quasi-sphere crystallites formed under extremely high supersaturation condition, which is difficult to be explained by the classical crystal growth theories. By analyzing the formation work of two-dimension crystal nuclei, we concluded that the crystal growth tend to be isotropic at extremely high supersaturation, which well explained the formation of the quasi-sphere crystallites.表面结构决定了晶体材料的许多重要的物理化学性质. 可控制备具有特定表面结构的微纳米晶体, 从而实现对晶体材料性能的改善, 引起了广泛的关注. 本课题组近期相关的研究表明, 晶体生长体系中, 生长单元的过饱和度决定了晶体的表面结构. 基于已有研究结果, 本文通过调节混合溶剂体系中乙二醇和水的相对体积比及NaOH的用量, 改变晶体生长体系中生长单元的过饱和度, 合成了亚微米尺寸的NaTaO3立方体、 削角立方体、 削角削棱立方体和准球体. 低过饱和度条件下, 形成的NaTaO3颗粒是低能{100}晶面裸露的立方体; 随过饱和度的增加, 立方体的角和棱逐渐削去, 裸露表面能更高的晶面; 极高过饱和度条件下, 则形成准球体NaTaO3颗粒. 这种准球体的形成难以用经典的晶体生长理论加以解释. 通过研究同样受过饱和度影响的二维晶核生成功(Whkl), 发现在极高的过饱和度的条件下, 晶体生长趋于各向同性, 合理地解释了准球体的形成机制.
Co-reporter:Qin Kuang, Xue Wang, Zhiyuan Jiang, Zhaoxiong Xie, and Lansun Zheng
Accounts of Chemical Research 2014 Volume 47(Issue 2) pp:308
Publication Date(Web):December 17, 2013
DOI:10.1021/ar400092x
Because many physical and chemical processes occur at surfaces, surface atomic structure is a critical factor affecting the properties of materials. Due to the presence of high-density atomic steps and edges and abundant unsaturated coordination sites, micro- and nanocrystallites with high-energy surfaces usually exhibit greater reactivity than those with low-energy surfaces. However, high-energy crystal surfaces are usually lost during crystal growth as the total surface energy is minimized. Therefore, the selective exposure of high-energy facets at the surface of micro- and nanocrystallites is an important and challenging research topic. Metal oxides play important roles in surface-associated applications, including catalysis, gas sensing, luminescence, and antibiosis. The synthesis of metal oxide micro- and nanocrystallites with specific surfaces, particularly those with high surface energies, is more challenging than the synthesis of metal crystals due to the presence of strong metal–oxygen bonds and diverse crystal structures.In this Account, we briefly summarize recent progress in the surface-structure-controlled synthesis of several typical metal oxide micro- and nanocrystallites, including wurtzite ZnO, anatase TiO2, rutile SnO2, and rocksalt-type metal oxides. We also discuss the improvement of surface properties, focusing on high-energy surfaces. Because of the huge quantity and diverse structure of metal oxides, this Account is not intended to be comprehensive. Instead, we discuss salient features of metal oxide micro- and nanocrystallites using examples primarily from our group.We first discuss general strategies for tuning the surface structure of metal oxide micro- and nanocrystallites, presenting several typical examples. For each example, we describe the basic crystallographic characteristics as well as the thermodynamic (i.e., tuning surface energy) or kinetic (i.e., tuning reaction rates) strategies we have used to synthesize micro- and nanocrystallites with high surface energies. We discuss the structural features of the specific facets and analyze the basis for the enhanced performance of the metal oxide micro- and nanocrystallites in water splitting, the degradation of organic pollutants, gas sensing, catalysis, luminescence, and antibiosis. Finally, we note the future trends in high-energy-facet metal oxide micro- and nanocrystallite research. A comprehensive understanding of the properties of metal oxide micro- and nanocrystallites with high-energy crystal surfaces and related synthetic strategies will facilitate the rational design of functional nanomaterials with desired characteristics.
Co-reporter:Yanyan Jia ; Yaqi Jiang ; Jiawei Zhang ; Lei Zhang ; Qiaoli Chen ; Zhaoxiong Xie ;Lansun Zheng
Journal of the American Chemical Society 2014 Volume 136(Issue 10) pp:3748-3751
Publication Date(Web):February 28, 2014
DOI:10.1021/ja413209q
Ultrathin crystalline nanosheets give an extremely high surface area of a specific crystal facet with unique physical and chemical properties compared with normal three-dimensionally polyhedral nanocrystals (NCs). However, the ultrathin metal nanosheets tend to curl themselves or assemble with each other sheet by sheet, which may reduce the effective surface area and accordingly the catalytic activity to a great extent. Here we report a facile wet-chemical route that allows the fabrication of novel excavated rhombic dodecahedral (ERD) PtCu3 alloy NCs with ultrathin nanosheets of high-energy {110} facets. The surface area was measured to be 77 m2 g–1 by CO stripping, although the particle size is about 50 nm. Electrochemical characterizations showed that the ERD PtCu3 NCs exhibit excellent electrocatalytic performance and high antipoisoning activity in comparison with commercial Pt black and PtCu3 alloy NCs with {111} surfaces.
Co-reporter:Qiaoli Chen, Jiawei Zhang, Yanyan Jia, Zhiyuan Jiang, Zhaoxiong Xie and Lansun Zheng
Nanoscale 2014 vol. 6(Issue 12) pp:7019-7024
Publication Date(Web):13 Mar 2014
DOI:10.1039/C4NR00313F
Platinum based alloy nanocrystals are promising catalysts for a variety of important practical process. However, it remains a great challenge to synthesize platinum-based intermetallic compound nanocrystals with well-defined surface structures. In this communication, taking the synthesis of concave cubic intermetallic Pt3Zn nanocrystals with {hk0} facets as an example, we proposed a new synthesis strategy for intermetallic compounds by reduction of noble metal precursors via a slow reduction process and reduction of transition metal ions via an underpotential deposition (UPD) process in wet chemical synthesis. The as-prepared intermetallic Pt3Zn nanocrystals exhibited superior CO poisoning tolerance and high electro-catalytic activity in both methanol and formic acid oxidation reactions in comparison with solid solution Pt3Zn nanocrystals and Pt/C.
Co-reporter:Junjie Ouyang, Jun Pei, Qin Kuang, Zhaoxiong Xie, and Lansun Zheng
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:12505
Publication Date(Web):July 8, 2014
DOI:10.1021/am502358g
Surface engineering of crystals at nanoscale level by precisely and rationally exposing specific facets proved to be highly effective in enhancing the performance of inorganic functional nanocrystals. To do so, a comprehensive understanding of the growth mechanism was of great importance. By using hematite (α-Fe2O3) as an example, in this paper we demonstrated high effectiveness of controlling supersaturation of growth monomers in engineering the exposed facets of nanocrystals. Under surfactant-free hydrothermal conditions, a series of morphology evolution of α-Fe2O3 nanocrystals from {012} faceted pseudocubes to {113} faceted hexagonal bipyramids and {001} faceted nanoplates were successfully activated through concentration-, reaction time-, and solvent-dependent hydrolysis of ferric acetylacetonate. High supersaturation was eventually proven to be conducive to the formation of facets with high surface energy. Furthermore, the α-Fe2O3 nanocrystals enclosed with facets of high surface energy exhibited excellent catalytic activity and gas-sensing ability. The present work will deepen our understanding of thermodynamics and kinetic control over the morphology of nanocrystals as well as our understanding of surface-related performance of inorganic functional nanocrystals.Keywords: CO catalysis; Gas sensing; Hematite; Shape evolution; Supersaturation
Co-reporter:Hai-xin Lin ; Zhi-chao Lei ; Zhi-yuan Jiang ; Chang-ping Hou ; De-yu Liu ; Min-min Xu ; Zhong-qun Tian
Journal of the American Chemical Society 2013 Volume 135(Issue 25) pp:9311-9314
Publication Date(Web):June 7, 2013
DOI:10.1021/ja404371k
Deduced from thermodynamics and the Thomson–Gibbs equation that the surface energy of crystal face is in proportion to the supersaturation of crystal growth units during the crystal growth, we propose that the exposed crystal faces can be simply tuned by controlling the supersaturation, and higher supersaturation will result in the formation of crystallites with higher surface-energy faces. We have successfully applied it for the growth of ionic (NaCl), molecular (TBPe), and metallic (Au, Pd) micro/nanocrystals with high-surface-energy faces. The above proposed strategy can be rationally designed to synthesize micro/nanocrystals with specific crystal faces and functionality toward specific applications.
Co-reporter:Chang Liu, Qin Kuang, Ming-Shang Jin, Jia-Wei Zhang, Xi-Guang Han, Zhao-Xiong Xie and Lan-Sun Zheng
Nanoscale 2013 vol. 5(Issue 5) pp:1793-1796
Publication Date(Web):21 Jan 2013
DOI:10.1039/C3NR34203D
A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers.
Co-reporter:Binjie Zheng, Xue Wang, Chang Liu, Kai Tan, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2013 vol. 1(Issue 40) pp:12635-12640
Publication Date(Web):23 Aug 2013
DOI:10.1039/C3TA12946B
In this article, single-crystalline tetrahedral Ag3PO4 microcrystals with exposed {111} facets was successfully synthesized via a facile wet chemical method. The tetrahedral Ag3PO4 with exposed {111} facets showed the highest photocatalytic activity in visible light irradiation among the {111}, {110} and {100} facets. By DFT calculations, it is demonstrated that the surface energy of the {111} facets is higher than that of the {110} and {100} facets. It was found that the largest band gap of the Ag3PO4 {111} surface is likely to suppress the recombination of electron–hole pairs by exploring the electronic structures of the different surfaces of Ag3PO4. Meanwhile, the dispersion between the valence bands and conduction bands of the {111} surface is beneficial for the separation of photogenerated electrons and holes on the {111} surface, which further improves the photocatalytic activity of the {111} surface.
Co-reporter:Xue Wang, Chang Liu, Binjie Zheng, Yaqi Jiang, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2013 vol. 1(Issue 2) pp:282-287
Publication Date(Web):02 Oct 2012
DOI:10.1039/C2TA00241H
Due to the fact that crystal facets with high surface energy usually exhibit superior performance in many fields, such as catalysis, the importance of the synthesis of micro/nano-crystals with exposed high surface energy facets is becoming a hot research field. In this article, concave Cu2O microcrystals mainly enclosed by {hhl} high-index facets have been successfully prepared by reducing Cu(CH3COO)2 with glucose in the presence of sodium dodecyl sulphate (SDS). SDS was proved to be important in the formation of the concave Cu2O microcrystals. The concave degree of truncated octahedra can be controlled by adjusting the concentration of SDS. In addition, we found the reaction rate also affected the morphology of Cu2O microcrystals. Octahedron-based branched particles, truncated concave octahedra and truncated octahedra can be obtained by adjusting the concentration of glucose. In the catalytic oxidation of CO, truncated concave octahedral Cu2O enclosed by {332} high-index facets exhibited the highest catalytic activity among the high-index {332} facets, low index {111} and {100} facets, due to the existence of high density steps on {332} facets and the CO catalytic activities of the crystal facets are in the sequence: {332} > {111} > {100}.
Co-reporter:Shixiong Bao, Jiawei Zhang, Zhiyuan Jiang, Xi Zhou, and Zhaoxiong Xie
The Journal of Physical Chemistry Letters 2013 Volume 4(Issue 20) pp:3440-3444
Publication Date(Web):September 26, 2013
DOI:10.1021/jz401682q
Due to the presence of high-density twinned-defects and diffuse elastic strain, pentagonal cyclic twinning (PCT) structures may have more fascinating properties than the corresponding single crystalline structure. Although there are a lot of reports concerning the PCT nanocrystals of many monometals and bimetal alloys, the established growth mechanisms of PCT structures are still not straightforward and usually inconsistent with each other. In this Letter, using dodecanethiol-capped Au nanocrystals (NCs) as building blocks, taking self-assembly of Au NCs into their colloidal crystals as the crystallization model, we found the competition of crystal cohesive energy and surface free energy plays an important role in the formation of PCT colloidal crystal. By rationally selecting the solvent to tailor the crystal cohesive energy, the structure of the colloidal crystals can be tuned. PCT structures are more likely to form when the interaction between building blocks is weak, while the single crystal structure is formed when the interaction is strong. The results demonstrate that the thermodynamic factors are the origin of pentagonal cyclic twinning.Keywords: Au nanocrystals; colloidal crystal; pentagonal cyclic twinning; self-assembly; thermodynamic analysis;
Co-reporter:Dr. Yaqi Jiang;Yanyan Jia;Jiawei Zhang;Lei Zhang;Huang Huang;Dr. Zhaoxiong Xie;Dr. Lansun Zheng
Chemistry - A European Journal 2013 Volume 19( Issue 9) pp:3119-3124
Publication Date(Web):
DOI:10.1002/chem.201203729
Abstract
PtCu alloy octahedral nanocrystals (NCs) have been synthesized successfully by using N,N-dimethylformamide as both the solvent and the reducing agent in the presence of cetyltrimethylammonium chloride. Cu underpotential deposition (UPD) is found to play a key role in the formation of the PtCu alloy NCs. The composition in the PtCu alloy can be tuned by adjusting the ratio of metal precursors in solution. However, the Cu content in the PtCu alloy NCs cannot exceed 50 %. Due to the fact that Cu precursor cannot be reduced to metallic copper and the Cu content cannot exceed 50 %, we achieved the formation of the PtCu alloy by using Cu UPD on the Pt surface. In addition, the catalytic activities of PtCu alloy NCs with different composition were investigated in electrocatalytic oxidation of formic acid. The results reveal that the catalytic performance is strongly dependent on PtCu alloy composition. The sample of Pt50Cu50 exhibits excellent activity in electrocatalytic oxidation of formic acid.
Co-reporter:Xiguang Han, Xi Zhou, Yaqi Jiang and Zhaoxiong Xie
Journal of Materials Chemistry A 2012 vol. 22(Issue 21) pp:10924-10928
Publication Date(Web):22 Mar 2012
DOI:10.1039/C2JM30843F
In this paper, we report the synthesis of spiral ZnO nanocrystals by the wet-chemical etching of pyramid ZnO nanoparticles in a solvent mixture of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that the OA in the mixed solvent acts as the etching agent. The formation of spiral ZnO nanoparticles is due to dislocations in the spiral shape surrounding the c axis formed during the growth of the pyramid ZnO nanoparticles. Moreover, the spiral ZnO nanoparticles exhibit much better gas sensing activity than the pyramid ZnO nanoparticles. Based on the structural analysis, we discuss the relationship between the surface structures and gas sensing properties.
Co-reporter:Shuifen Xie, Binjie Zheng, Qin Kuang, Xue Wang, Zhaoxiong Xie and Lansun Zheng
CrystEngComm 2012 vol. 14(Issue 22) pp:7715-7720
Publication Date(Web):
DOI:10.1039/C2CE25797A
Co-reporter:Xue Wang, Zhiyuan Jiang, Binjie Zheng, Zhaoxiong Xie and Lansun Zheng
CrystEngComm 2012 vol. 14(Issue 22) pp:7579-7582
Publication Date(Web):01 May 2012
DOI:10.1039/C2CE25333J
CeO2 nanocubes and CeO2 truncated octahedra have been synthesized with different capping agents in the alkaline environment. The CeO2 nanocubes present enhanced catalytic properties in CO catalytic oxidation, which may be due to the existence of more coordination of unsaturated cerium atoms and more active adsorption of dissociated oxygen species on the CeO2 (100) surface.
Co-reporter:Ya-Qi Jiang, Chun-Xiao He, Ran Sun, Zhao-Xiong Xie, Lan-Sun Zheng
Materials Chemistry and Physics 2012 Volume 136(2–3) pp:698-704
Publication Date(Web):15 October 2012
DOI:10.1016/j.matchemphys.2012.07.044
Zinc stannate (Zn2SnO4) cube-like hierarchical structures assembled by nanoplate arrays have been successfully synthesized by a facile solvothermal method in the presence of tetraethylammonium hydroxide. The formation mechanism and effects of surfactants and reaction temperature on the products were investigated. In addition, studies of the gas-sensing property demonstrated that the as-synthesized Zn2SnO4 with hierarchical structures exhibited better gas-sensing property than that of normal Zn2SnO4 nanopartilces.Highlights► Zn2SnO4 hierarchical cube-like structure has been synthesized solvothermally. ► ZnSn(OH)6 microcube directed the formation of Zn2SnO4 hierarchical structure. ► The as-prepared Zn2SnO4 exhibits structure-enhanced gas-sensing property.
Co-reporter:Jiawei Zhang;Lei Zhang;Yanyan Jia;Guangxu Chen;Xue Wang;Qin Kuang
Nano Research 2012 Volume 5( Issue 9) pp:618-629
Publication Date(Web):2012 September
DOI:10.1007/s12274-012-0247-9
Co-reporter:Lei Zhang;Dingqiong Chen;Zhiyuan Jiang;Jiawei Zhang;Shuifen Xie
Nano Research 2012 Volume 5( Issue 3) pp:181-189
Publication Date(Web):2012 March
DOI:10.1007/s12274-012-0198-1
Platinum (Pt) is an outstanding catalyst for many important industrial products. Because of its high cost and scarce reserves, it is very important to improve the performance of Pt catalysts. As the metal nanocrystals (NCs) with high-index surfaces usually show very good catalytic activity because of their high density of atomic steps and kinks, the preparation of Pt NCs with high-index facets has become a very important and hot research topic recently. In this article, we report a facile synthesis of high-yield Pt NCs with a series of {hkk} high-index facets including {211} and {411} via a solvothermal method using Pt(II) acetylacetonate as the Pt source, 1-octylamine as the solvent and capping agent, and formaldehyde as an additional surface structure regulator. Multipod Pt NCs with dominant {211} side surfaces were produced without formaldehyde, while concave Pt NCs with dominant {411} surfaces formed under the influence of formaldehyde. By analyzing the products by IR spectroscopy, we found the presence of CO on the surface of concave Pt NCs with {411} surfaces prepared from the solution containing formaldehyde. It was concluded that amine mainly stabilized the monoatomic step edges, resulting in the {211} exposed surface; with addition of formaldehyde, it decomposed into CO, leading to the formation of {411} surfaces by the additional adsorption of the CO on the {100} terraces. In addition, it was found that the as-prepared Pt NCs with high-index {211} and {411} surfaces exhibited much better catalytic activity in the electro-oxidation of ethanol than a commercial Pt/C catalyst or Pt nanocubes with low-index {100} surfaces, and the catalytic activities of Pt crystal facets decreased in the sequence {411}>{211}>{100}.
Open image in new window
Co-reporter:Dr. Xiguang Han;Binjie Zheng;Junjie Ouyang;Xue Wang;Dr. Qin Kuang;Dr. Yaqi Jiang; Zhaoxiong Xie;Lansun Zheng
Chemistry – An Asian Journal 2012 Volume 7( Issue 11) pp:2538-2542
Publication Date(Web):
DOI:10.1002/asia.201200474
Co-reporter:Xue Wang;Xiguang Han;Shuifen Xie;Dr. Qin Kuang;Yaqi Jiang;Subing Zhang;Xiaoliang Mu;Guangxu Chen; Zhaoxiong Xie; Lansun Zheng
Chemistry - A European Journal 2012 Volume 18( Issue 8) pp:2283-2289
Publication Date(Web):
DOI:10.1002/chem.201103280
Abstract
A morphology evolution of SnO2 nanoparticles from low-energy facets (i.e., {101} and {110}) to high-energy facets (i.e., {111}) was achieved in a basic environment. In the proposed synthetic method, octahedral SnO2 nanoparticles enclosed by high-energy {111} facets were successfully synthesized for the first time, and tetramethylammonium hydroxide was found to be crucial for the control of exposed facets. Furthermore, our experiments demonstrated that the SnO2 nanoparticles with exposed high-energy facets, such as {221} or {111}, exhibited enhanced catalytic activity for the oxidation of CO and enhanced gas-sensing properties due to their high chemical activity, which results from unsaturated coordination of surface atoms, superior to that of low-energy facets. These results effectively demonstrate the significance of research into improving the physical and chemical properties of materials by tailoring exposed facets of nanomaterials.
Co-reporter:Lei Zhang ; Jiawei Zhang ; Qin Kuang ; Shuifen Xie ; Zhiyuan Jiang ; Zhaoxiong Xie ;Lansun Zheng
Journal of the American Chemical Society 2011 Volume 133(Issue 43) pp:17114-17117
Publication Date(Web):September 6, 2011
DOI:10.1021/ja2063617
Controlled syntheses of multicomponent metal nanocrystals (NCs) and high-index surfaces have attracted increasing attention due to the specific physical and chemical properties of such NCs. Taking advantage of copper underpotential deposition as a bridge, hexoctahedral Au–Pd alloy NCs with {hkl} facets exposed were successfully synthesized, while phase separation occurred in the absence of Cu2+ ions. The as-prepared hexoctahedral Au–Pd alloy NCs exhibited very excellent performance in terms of both formic acid electro-oxidation and methanol tolerance due to synergism between the high-index facets and the alloy.
Co-reporter:Lei Zhang, Jiawei Zhang, Zhiyuan Jiang, Shuifen Xie, Mingshang Jin, Xiguang Han, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 vol. 21(Issue 26) pp:9620-9625
Publication Date(Web):03 Jun 2011
DOI:10.1039/C0JM04407E
Pd-based catalysts are of great interest both for fundamental research and applications. It still remains a challenge to develop reliable and versatile approaches to prepare Pd-based nanostructures with higher performance and better stability. In this article, a facile solution route has been developed to prepare Pd nanospheres, as well as Pd–Pt, Pd–Ag and Pd–Pt–Ag alloy nanospheres. SEM and TEM investigations revealed that the as-prepared nanospheres were three-dimensionally interconnected porous networks with primary nanoparticles as building blocks. The chemical composition of these nanospheres can be easily adjusted by controlling the molar ratio of precursors. Electrochemical measurements indicated that the electrocatalytic activity of these nanospheres towards formic acid oxidation depended on the composition of the nanospheres. By judiciously adjusting the composition of the Pd based alloy nanospheres, the performance of the Pd based catalysts, i.e., the onset potential of the formic acid oxidation, the corresponding peak current density and the ability to tolerate CO, can be optimized.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Yang Zhao, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 vol. 21(Issue 20) pp:7263-7268
Publication Date(Web):15 Apr 2011
DOI:10.1039/C1JM10745C
We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 ± 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Jie Fu, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Chemical Communications 2011 vol. 47(Issue 23) pp:6722-6724
Publication Date(Web):11 May 2011
DOI:10.1039/C1CC11542A
Three-dimensional, hollow, anatase TiO2 boxes, each was enclosed by six single-crystalline TiO2 plates exposed with highly reactive {001} facets, were facilely obtained by calcining a cubic TiOF2 solid precursor at 500–600 °C. The formation of such particular nanostructures is attributed to the hard self-template restriction and the adsorption of F− ions from the TiOF2.
Co-reporter:Jiawei Zhang;Lei Zhang;Shuifen Xie;Dr. Qin Kuang;Xiguang Han; Zhaoxiong Xie; Lansun Zheng
Chemistry - A European Journal 2011 Volume 17( Issue 36) pp:9915-9919
Publication Date(Web):
DOI:10.1002/chem.201100868
Co-reporter:Qingning Jiang;Zhiyuan Jiang;Lei Zhang;Haixin Lin;Ning Yang;Huan Li
Nano Research 2011 Volume 4( Issue 6) pp:612-622
Publication Date(Web):2011 June
DOI:10.1007/s12274-011-0117-x
Co-reporter:Shuang Zhou, Shao-Yu Mao, Zhao-Xiong Xie, Lan-Sun Zheng
Sensors and Actuators B: Chemical 2011 Volume 156(Issue 1) pp:23-27
Publication Date(Web):10 August 2011
DOI:10.1016/j.snb.2011.03.068
Fe-doped yttrium manganate (YMn(1−x)FexO3) nanoparticles were synthesized by the precursor method. X-ray diffractions showed that the structures of the as-prepared powders were crystallized in the normal yttrium manganate phase (space group: P63cm) when doping concentration was low, while they were crystallized into the high-temperature yttrium manganate phase (space group: P63/mmc) at a high doping concentration. Then, the gas sensing properties of YMnO3 and YMn(1−x)FexO3 nanoparticles were studied for the first time. Both YMnO3 and YMn(1−x)FexO3 exhibited sensor response to alcohols, organic amines, dichloromethane, acetone, acetonitrile, methylbenzene, THF and so on. Interestingly, high-concentration Fe-doped yttrium manganate showed much better sensor response than that of normal yttrium manganate phase. We conclude that the multiferroic material of YMn(1−x)FexO3 is a promising potential new ABO3 type gas sensing material.
Co-reporter:Zhi-Yuan Jiang;Qin Kuang;Lan-Sun Zheng
Advanced Functional Materials 2010 Volume 20( Issue 21) pp:3634-3645
Publication Date(Web):
DOI:10.1002/adfm.201001243
Abstract
Recently, special attention has been paid to the syntheses of micro/nanostructured crystallites with high-energy crystal facets, because high-energy crystal surfaces usually exhibit fascinating surface-enhanced properties and have promising applications in catalysis, photoelectrical devices, and energy conversion, etc. With particular emphasis on the results obtained by the authors’ research group, this feature article gives a brief review of recent progress in the field of surface/morphology controlled syntheses, focusing on high-energy crystal surfaces of five kinds of inorganic functional material, with the wurtzite, rocksalt, anatase, rutile, and face-centered cubic structures, respectively. Combined with the theoretical and experimental research results as well as crystal structure models, the intrinsic causes for surface-dependent chemical/physical properties of those materials with high-energy surfaces are further discussed.
Co-reporter:Jiangtao Wu, Shaoyu Mao, Zuo-Guang Ye, Zhaoxiong Xie and Lansun Zheng
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 6) pp:1561
Publication Date(Web):May 20, 2010
DOI:10.1021/am1002052
Unusual room-temperature weak ferromagnetism α-Fe2O3 was prepared by heating the mixture of commercial α-Fe2O3 (as raw material) and tartaric acid at a mild temperature of 250 °C. This reaction involves a fast heating and cooling process resulting from the self-catalyzed oxidation of tartaric acid. Careful chemical analyses confirmed that no any ferromagnetic impurities, such as Fe, Fe3O4, amorphous iron oxide and γ-Fe2O3, were present in the treated sample. The unusual weak ferromagnetism was then attributed to the formation of a large amount of point defects in the treated sample during the peculiar synthetic process. Such a mechanism is supported by the result of annealing, which reduces the amount of point defects and thereby reestablishes the original antiferromagnetism in α-Fe2O3.Keywords: catalyzed oxidation; ferromagnetism; hematite; point defect
Co-reporter:Zukui Pei, Lili Lin, Haiming Zhang, Lei Zhang, Zhaoxiong Xie
Electrochimica Acta 2010 Volume 55(Issue 27) pp:8287-8292
Publication Date(Web):30 November 2010
DOI:10.1016/j.electacta.2010.01.088
Self-assemblies of 2,6-naphthalenedicarboxylic acid (NDC) and 4,4′-biphenyldicarboxylic acid (BDC) molecules on the highly oriented pyrolytic graphite (HOPG) and reconstructed Au(1 1 1) surfaces has been, respectively, studied by using scanning tunneling microscopy (STM). The NDC molecules form an incommensurate structure, while BDC molecules form a commensurate structure on the HOPG surface. The aromatic rings take the same orientation with that of the underlying HOPG substrate to gain optimum adsorbate–substrate interactions. On the Au(1 1 1) surface, both molecules form incommensurate structures. The orientations of aromatic ring locate about 20° with respect to the gold rows, the 〈1 1 0〉 direction. On the HOPG surface, the whole carboxyl groups are invisible, while the carbon atoms of the carboxyl groups may appear bright on the gold surface.
Co-reporter:Xian-Hua Zhang, Xiaodong Yi, Jiawei Zhang, Zhaoxiong Xie, Junyong Kang, and Lansun Zheng
Inorganic Chemistry 2010 Volume 49(Issue 22) pp:10244-10246
Publication Date(Web):October 11, 2010
DOI:10.1021/ic1018949
Apatite-type La9.33(SiO4)6O2 hollow nanoshells were successfully synthesized by a controlled route. These oxide-ion-conducting hollow nanoshells were used to catalyze oxidative coupling of methane, and an enhanced catalytic performance at relatively low temperature was realized. The high-activity and energy-saving features were attributed to their hollow nanostructures and oxide ion conductivity.
Co-reporter:Ming-Shang Jin, Qin Kuang, Xi-Guang Han, Shui-Fen Xie, Zhao-Xiong Xie, Lan-Sun Zheng
Journal of Solid State Chemistry 2010 Volume 183(Issue 6) pp:1354-1358
Publication Date(Web):June 2010
DOI:10.1016/j.jssc.2010.04.017
Here we proposed a synthetic method of high-purity Ag nanoplates by the reduction of aqueous Ag+ ions at the aqueous–organic interface with the reductant ferrocene. We demonstrated that the as-prepared Ag nanoplates can be widely tunable from 600 nm to 7 μm in size and from 10 to 35 nm in thickness, simply by adjusting the component of organic phase. To our knowledge, there are few methods to tailor the size and the thickness of metal nanoplates in such a large range although many efforts have been made aiming to realize it. Our proposed synthetic strategy is rapid, template-free, seed-less, and high-yield, and could be applied to synthesize analogous two-dimensional nanostructures of other noble metals, such as Pt, Au, and Pd.High-purity Ag nanoplates were synthesized by the reduction of aqueous Ag+ ions at the aqueous–organic interface with the reductant ferrocene, the size and thickness of which were widely tunable.
Co-reporter:YaQi Jiang;FangFang Li;Ran Sun;ZhaoXiong Xie;LanSun Zheng
Science China Chemistry 2010 Volume 53( Issue 8) pp:1711-1717
Publication Date(Web):2010 August
DOI:10.1007/s11426-010-3160-7
ZnO nanoparticles with different morphologies were solvothermally synthesized by controlling the alkali (sodium hydroxide) concentration in an isopropanol solution. The products were characterized by means of powder X-ray diffraction, UV-visible absorption spectra, scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction. The morphologies of the formed ZnO nanocrystals were dependent on the concentration of the alkali, and with increases of sodium hydroxide concentration, the ZnO nanocrystals evolved from rod to hexagonal bipyramid, and then to a flower-like nanostructure. The flower-like nanostructure resulted from the etching of the hexagonal bipyramid by the excess alkali. The photoluminescence and photocatalytic properties of the prepared ZnO were investigated. The difference of green emission among the ZnO nanocrystals indicated that a higher sodium hydroxide concentration led to a higher level of defects. The size, the surface structure and defects in the ZnO nanocrystals affected its photo-degradation characteristics.
Co-reporter:Xi-Guang Han, Ya-Qi Jiang, Shui-Fen Xie, Qin Kuang, Xi Zhou, Dao-Ping Cai, Zhao-Xiong Xie and Lan-Sun Zheng
The Journal of Physical Chemistry C 2010 Volume 114(Issue 22) pp:10114-10118
Publication Date(Web):May 13, 2010
DOI:10.1021/jp101284p
In this article, we demonstrate successful application of a top-down strategy based on a selective wet-chemical etching technique in fabrication of nanostructures with a special morphology. Pagoda-like and hexagonal pyramidal ZnO nanostructures with the polar (0001̅) and {101̅1} planes as exposed surfaces have been synthesized by refluxing ZnO columns mainly bounded with {101̅0} nonpolar faces in the mixed solvent of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that OA in the mixed solvent acts as the etchant in the process of morphology evolution, and the appropriate proportion of OA, reaction time, and reaction temperature are crucial for controlling the etching degree of ZnO. Through the selective wet-chemical etching, it has been confirmed that the dumbbell-like ZnO is of twinning morphologies growing along contrary direction on both sides of the (0001) twinning plane. Therefore, our present work provides a simple way to estimate the complicated twinning phenomena.
Co-reporter:Yaqi Jiang, Jie Chen, Zhaoxiong Xie, Lansun Zheng
Materials Chemistry and Physics 2010 120(2–3) pp: 313-318
Publication Date(Web):
DOI:10.1016/j.matchemphys.2009.11.002
Co-reporter:Xin Wang, Hui-Fang Wu, Qin Kuang, Rong-Bin Huang, Zhao-Xiong Xie and Lan-Sun Zheng
Langmuir 2010 Volume 26(Issue 4) pp:2774-2778
Publication Date(Web):October 9, 2009
DOI:10.1021/la9028172
Ag2O particles with different polyhedral shapes including octahedron, truncated octahedron, and cube were successfully synthesized by a simple wet-chemical method using silver nitrate, ammonia, and sodium hydroxide as raw materials at room temperature. Simply by tuning the concentration of starting materials, the shape of Ag2O particles evolved from octahedron to cube, and the size gradually decreased from 1−2 μm to 400−700 nm. As examples for promising applications, the antibacterial activities of the as-prepared Ag2O polyhedral particles were preliminarily studied. It has been found the antibacterial activity of Ag2O particles against E. coli depends on the shape of Ag2O particles, demonstrating that the surface structure of Ag2O particles affects the antibacterial activity.
Co-reporter:Qin Kuang, Tao Xu, Zhao-Xiong Xie, Shui-Chao Lin, Rong-Bin Huang and Lan-Sun Zheng
Journal of Materials Chemistry A 2009 vol. 19(Issue 7) pp:1019-1023
Publication Date(Web):26 Nov 2008
DOI:10.1039/B815514C
In this paper, we describe an effective two-step method for fabricating aligned SnO2nanotube arrays by using various pre-synthesized ZnO nanorod arrays as sacrificial templates. The composition and structure of as-synthesized SnO2nanotube arrays were analyzed in detail by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Because there is a special epitaxial relation between the SnO2 walls and ZnO templates, the walls building the SnO2nanotubes are highly orientated and nearly single-crystalline. Our present study provides an opportunity to investigate related physical and chemical properties and potential applications of such aligned SnO2nanotubes with nearly single-crystalline nature.
Co-reporter:Tao Xu, Xi Zhou, Zhiyuan Jiang, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
Crystal Growth & Design 2009 Volume 9(Issue 1) pp:192
Publication Date(Web):November 19, 2008
DOI:10.1021/cg8002096
In this paper, a general method for the preparation of metal oxides with all polar surfaces exposed is presented. The syntheses of the products were carried out with simply performing reactions in a molten salt system, in which cations and anions tend to have strong electrostatic interactions with positive or negative charged polar planes so as to lower the surface energy and slow down the growth rate of polar planes, resulting in the formation of exposed polar surfaces. With this strategy, wurtzite structured ZnO, rocksalt structured MgO, spinel structured Co3O4, and ternary element compound ZnFe2O4 of spinel structure were successfully synthesized with all polar surfaces exposed, which demonstrated a universality of our proposed strategy.
Co-reporter:Xi-Guang Han, Ming-Shang Jin, Qin Kuang, Xi Zhou, Zhao-Xiong Xie and Lan-Sun Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 7) pp:2867-2872
Publication Date(Web):2017-2-22
DOI:10.1021/jp8092836
In this paper, we successfully synthesized six-horn-like branched MnO nanocrystals by thermal decomposition of Mn(CH3CO2)2·4H2O in the present of 1-octylamine/oleic acid (OA) at 400 °C for 30 min. SEM and TEM observation indicate that every horn of six-horn-like MnO nanocrystals is constructed with a bundle of nanorods growing along the [100] direction. Adequate evidence provided by time- and temperature-dependent experiments demonstrates that the formation of such branched MnO can be divided into two processes, i.e., the formation of octahedron-based MnO exposed with polar surfaces and sequent directional etching. In this mechanism, the mixed solvent of organic amines and OA provides favorable circumstances for the formation of MnO octahedra, and at the same time, OA as the etching reagent is responsible for the evolution of six-horn-like MnO from octahedron-based MnO.
Co-reporter:Shuifen Xie, Xi Zhou, Xiguang Han, Qin Kuang, Mingshang Jin, Yaqi Jiang, Zhaoxiong Xie and Lansun Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 44) pp:19107-19111
Publication Date(Web):October 8, 2009
DOI:10.1021/jp907651d
Guided by the concept of regarding nanoparticles as superatoms or supermolecules in colloidal solution, we design a facile crystallization approach for preparation of 3D supercrystals (SCs). Dispersive states of as-prepared MnO nanocrystals (NCs) in solvents of cyclohexane and ethanol were studied to illuminate the effects of solvents. Ethanol was demonstrated to be the most appropriate solvent, and a large amount of microscale cubic SCs built by octahedral MnO NCs was created via direct crystallization. Although two types of packing structures are well-defined, the MnO SCs prefer the one with the higher packing efficiency of 88.89% for minimizing system energy. The crystallization process undergoes a dynamic attachment and exchange mechanism.
Co-reporter:Hai-Ming Zhang, Zu-Kui Pei, Zhao-Xiong Xie, La-Sheng Long, Bing-Wei Mao, Xin Xu and Lan-Sun Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 31) pp:13940-13946
Publication Date(Web):July 2, 2009
DOI:10.1021/jp903406q
A kind of robust molecular template formed between melamine (M) and cyanuric acid (CA) molecules on highly oriented pyrolytic graphite (HOPG) surfaces has been prepared by putting a droplet of hot aqueous solutions containing equal mol of M and CA molecules on preheated substrate. The CA·M SAMs exhibit features of hexagonal open networks which makes them an ideal molecular template for further processing of functional guest entities. In addition to the preparation of CA·M SAMs, SAMs of M and CA molecules alone were also studied on HOPG surfaces. Chiral structures were found in the SAMs of M molecules.
Co-reporter:Xiguang Han;Mingshang Jin;Shuifen Xie;Qin Kuang Dr.;Zhiyuan Jiang Dr.;Yaqi Jiang;Zhaoxiong Xie ;Lansun Zheng
Angewandte Chemie International Edition 2009 Volume 48( Issue 48) pp:9180-9183
Publication Date(Web):
DOI:10.1002/anie.200903926
Co-reporter:Bing-Qiang Huang, Li Wang, Kang Shi, Zhao-Xiong Xie, Lan-Sun Zheng
Journal of Electroanalytical Chemistry 2008 Volume 615(Issue 1) pp:19-24
Publication Date(Web):1 April 2008
DOI:10.1016/j.jelechem.2007.11.022
PMo12O403- anion modified electrodes were prepared by simply immersing the glassy carbon electrode in the saturated BMIM+BF4- ionic liquid solution of polyoxometalates (POMs). The electrochemical properties of the as-prepared POM-modified glassy carbon electrode were investigated by cyclic voltammetry, which not only displayed a reversible redox electrochemical behavior and high stability in aqueous solutions, but also exhibited a good electrocatalytic activity toward the reduction of nitrite. Because of the simpleness of the preparation method, stable and reproducible electrochemical properties of the as-prepared POMs modified electrode, the proposed strategy shows remarkable advantages and should be important for practical applications.
Co-reporter:Mingshang Jin, Qin Kuang, Zhiyuan Jiang, Tao Xu, Zhaoxiong Xie, Lansun Zheng
Journal of Solid State Chemistry 2008 Volume 181(Issue 9) pp:2359-2363
Publication Date(Web):September 2008
DOI:10.1016/j.jssc.2008.05.034
High-yield silver/polymer/carbon nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. High-resolution TEM and element mapping proved that as-prepared nanocables consist of a silver nanowire core, a polymer inner shell, and a graphitic carbon outer shell. A three-step growth mechanism was proposed to explain the growth of such three-layer nanocables, i.e. the formation of silver nanowires, the glycosidation of glucose molecules on silver nanowire surface and the carbonization of the outmost glycosidation layer. We believe that reaction temperature plays the key role in the polymerization of glucose and sequent surface-carbonization.High-yield silver/polymer/carbon coaxial nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. Our experiments indicate that such novel nanostructures formed through the growth mechanism that the silver nanowires grow first, and then glycosidation of glucose occurs on the silver nanowire surfaces, and finally the partial carbonization occurs on the outmost surface of the polymer layer.
Co-reporter:Yan-Yun Ma, Zhi-Yuan Jiang, Qin Kuang, Shu-Hong Zhang, Zhao-Xiong Xie, Rong-Bin Huang and Lan-Sun Zheng
The Journal of Physical Chemistry C 2008 Volume 112(Issue 35) pp:13405-13409
Publication Date(Web):2017-2-22
DOI:10.1021/jp803459c
In recent years, considerable attention has been focused on various polyhedron-based branched particles due to their fundamental significance and widespread potential application. However, knowledge of the original nature and growth mechanisms for these complicated structures is still limited. In this paper, polyhedron-based branched Cu2O microcrystals have been prepared via an electrodeposition process without any surfactant at room temperature. The electron diffraction pattern of the branched Cu2O microcrystals can be indexed as a single crystal, as many other polyhedron-based branched crystals exhibit. By carefully analyzing the intensities of the diffraction spots we, for the first time, conclude that the single-crystal-like Cu2O branched particles are in fact twinning crystals. It could be anticipated that the crystal twinning (or the stacking fault) could be popular in the single-crystal-like branched particles.
Co-reporter:Yanyun Ma;Qin Kuang Dr.;Zhiyuan Jiang Dr.;Zhaoxiong Xie ;Rongbin Huang ;Lansun Zheng
Angewandte Chemie International Edition 2008 Volume 47( Issue 46) pp:8901-8904
Publication Date(Web):
DOI:10.1002/anie.200802750
Co-reporter:Yanyun Ma;Qin Kuang Dr.;Zhiyuan Jiang Dr.;Zhaoxiong Xie ;Rongbin Huang ;Lansun Zheng
Angewandte Chemie 2008 Volume 120( Issue 46) pp:9033-9036
Publication Date(Web):
DOI:10.1002/ange.200802750
Co-reporter:Qin Kuang, Chang-Shi Lao, Zhou Li, Yu-Zi Liu, Zhao-Xiong Xie, Lan-Sun Zheng and Zhong Lin Wang
The Journal of Physical Chemistry C 2008 Volume 112(Issue 30) pp:11539-11544
Publication Date(Web):July 3, 2008
DOI:10.1021/jp802880c
Field-effect transistors based on a single SnO 2 nanowire were successfully fabricated, and their photon- and gas-sensing properties were investigated. It is found that the sensitivity of single SnO 2 nanowire based devices was remarkably improved by surface functionalization with ZnO or NiO nanoparticles. The heterojunction between the surface coating layers and SnO 2 and the corresponding coupling effect of the two sensing materials play a critical role in controlling device sensitivity.
Co-reporter:Qin Kuang, Zhi-Wei Lin, Wei Lian, Zhi-Yuan Jiang, Zhao-Xiong Xie, Rong-Bin Huang, Lan-Sun Zheng
Journal of Solid State Chemistry 2007 Volume 180(Issue 4) pp:1236-1242
Publication Date(Web):April 2007
DOI:10.1016/j.jssc.2007.01.021
In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol–gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc.A versatile synthetic method for the preparation of ordered rare-earth (RE) oxide nanotubes is reported, by which RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol–gel method assisted with porous anodic aluminum oxide (AAO) templates.
Co-reporter:Hai-Ming Zhang;Jia-Wei Yan Dr. Dr.;Bing-Wei Mao Dr.;Xin Xu Dr.
Chemistry - A European Journal 2006 Volume 12(Issue 15) pp:
Publication Date(Web):14 MAR 2006
DOI:10.1002/chem.200500962
Self-assembled monolayers (SAMs) of alkanols (1-CNH2N+1OH) with varying carbon-chain lengths (N=10–30) have been systematically studied by means of scanning tunneling microscopy (STM) at the interfaces between alkanol solutions (or liquids) and Au(111) surfaces. The carbon skeletons were found to lie flat on the surfaces. This orientation is consistent with SAMs of alkanols on highly oriented pyrolytic graphite (HOPG) and MoS2 surfaces, and also with alkanes on reconstructed Au(111) surfaces. This result differs from a prior report, which claimed that 1-decanol molecules (N=10) stood on their ends with the OH polar groups facing the gold substrate. Compared to alkanes, the replacement of one terminal CH3 group with an OH group introduces new bonding features for alkanols owing to the feasibility of forming hydrogen bonds. While SAMs of long-chain alkanols (N>18) resemble those of alkanes, in which the aliphatic chains make a greater contribution, hydrogen bonding plays a more important role in the formation of SAMs of short-chain alkanols. Thus, in addition to the titled lamellar structure, a herringbone-like structure, seldom seen in SAMs of alkanes, is dominant in alkanol SAMs for values of N<18. The odd–even effect present in alkane SAMs is also present in alkanol SAMs. Thus, the odd N alkanols (alkanols with an odd number of carbon atoms) adopt perpendicular lamellar structures owing to the favorable interactions of the CH3 terminal groups, similar to the result observed for odd alkanes. In contrast to alkanes on Au(111) surfaces, for which no SAMs on an unreconstructed gold substrate were observed, alkanols are capable of forming SAMs on either the reconstructed or the unreconstructed gold surfaces. Structural models for the packing of alkanol molecules on Au(111) surfaces have been proposed, which successfully explain these experimental observations.
Co-reporter:Xi Zhou, Zhao-Xiong Xie, Zhi-Yuan Jiang, Qin Kuang, Shu-Hong Zhang, Tao Xu, Rong-Bin Huang and Lan-Sun Zheng
Chemical Communications 2005 (Issue 44) pp:5572-5574
Publication Date(Web):12 Oct 2005
DOI:10.1039/B510287A
Wurtzite ZnO hexagonal micro-pyramids, with all exposed surfaces being polar ±
(0001) and {101} planes, have been successfully synthesized using ionic liquids as solvents.
Co-reporter:Ying Chen, Xin Gu, Cha-Geng Nie, Zhi-Yuan Jiang, Zhao-Xiong Xie and Chang-Jian Lin
Chemical Communications 2005 (Issue 33) pp:4181-4183
Publication Date(Web):13 Jul 2005
DOI:10.1039/B504911C
The shape of gold nanoparticles has been successfully tuned among penta-twinned decahedrons, truncated tetrahedrons, cubes, octahedrons, hexagonal thin plates by introducing a small amount of salt into a N,N-dimethylformamide (DMF) solution containing poly(vinyl pyrrolidone)
(PVP), and changing the temperature or the concentration of the gold precursor.
Co-reporter:Zhao-Xiong Xie, Ken-ichi Tanaka
Ultramicroscopy 2005 Volume 105(1–4) pp:6-11
Publication Date(Web):November 2005
DOI:10.1016/j.ultramic.2005.06.010
Adsorption of Zn atoms on a Si(1 0 0)-2×1 surface was studied by scanning tunneling microscopy at room temperature. Narrow lines are grown perpendicular to the Si-dimer rows of the [1 1 0] direction at low coverage. The narrow line is formed by arraying rectangular Zn3 dots, where a dot is composed of one Zn atom on a Si dimer and the other two in the neighboring two hollow sites. When the Si(1 0 0)-2×1 surface is covered with one monolayer of Zn, a 4×1 structure is established. More deposition of Zn on the 4×1 monolayer grows into three-dimensional Zn islands.
Co-reporter:Z.-Y. Jiang;Z.-X. Xie;X.-H. Zhang;S.-C. Lin;T. Xu;S.-Y. Xie;R.-B. Huang;L.-S. Zheng
Advanced Materials 2004 Volume 16(Issue 11) pp:
Publication Date(Web):17 JUN 2004
DOI:10.1002/adma.200306635
Co-reporter:Shu-Hong Zhang, Zhao-Xiong Xie, Zhi-Yuan Jiang, Xin Xu, Juan Xiang, Rong-Bin Huang and Lan-Sun Zheng
Chemical Communications 2004 (Issue 9) pp:1106-1107
Publication Date(Web):05 Apr 2004
DOI:10.1039/B315931K
An electroless deposition method has been employed for the synthesis of silver nanotubes using porous anodic aluminium oxide as templates, by which high-yield silver nanotubes with length over ten microns have been synthesized.
Co-reporter:Hai-Ming Zhang Dr.;Bing-Wei Mao Dr.;Xin Xu Dr.
Chemistry - A European Journal 2004 Volume 10(Issue 6) pp:
Publication Date(Web):15 MAR 2004
DOI:10.1002/chem.200305334
The self-assembled monolayers (SAMs) of normal alkanes (n−CnH2n+2) with different carbon chain lengths (n=14–38) in the interfaces between alkane solutions (or liquids), and the reconstructed Au (111) surfaces have been systematically studied by means of scanning tunneling microscopy (STM). In contrast to previous studies, which concluded that some n-alkanes (n=18–26) can not form well-ordered structures on Au (111) surfaces, we observed SAM formations for all these n-alkanes without any exceptions. We find that gold reconstruction plays a critical role in the SAM formation. The alkane monolayers adopt a lamellar structure in which the alkane molecules are packed side-by-side, to form commensurate structures with respect to the reconstructed Au (111) surfaces. The carbon skeletons are found to lie flat on the surfaces, which is consistent with the infrared spectroscopic studies. Interestingly, we find that two-dimensional chiral lamellar structures form for alkanes with an even carbon number due to the specific packing of alkane molecules in a tilted lamella. Furthermore, we find that the orientation of alkane molecules deviates from the exact [01] direction, because of the intermolecular interactions among the terminal methyl groups of neighboring lamellae; this results in differences of molecular orientation between mirror structures of adjacent zigzag alkane lamellae. Structural models have been proposed, that shed new light on monolayer formation.
Co-reporter:Zhao-Xiong Xie, Zhi-Feng Huang and Xin Xu
Physical Chemistry Chemical Physics 2002 vol. 4(Issue 8) pp:1486-1489
Publication Date(Web):14 Mar 2002
DOI:10.1039/B109159J
Ordered normal-alkane monolayers of lamellar structures are found to form in the interface between alkane solutions and the reconstructed Au (111) surfaces. The boundaries of the lamellae may exhibit a zigzag shape. In the alkane monolayers, two kinds of packing of the alkane molecules are observed. The packing patterns are correlated to the structure of the gold surface and the molecular lengths of the alkanes. The orientation of alkane molecules is gently disturbed by the reconstructed gold ridges. Furthermore, the lamellar boundaries are located on the elbow positions of the reconstructed gold surfaces for long-chain alkanes. These results demonstrate that the structures of self-assembled monolayers of normal alkanes are sensitive to the structures of the Au (111) surfaces.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Jie Fu, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Chemical Communications 2011 - vol. 47(Issue 23) pp:NaN6724-6724
Publication Date(Web):2011/05/11
DOI:10.1039/C1CC11542A
Three-dimensional, hollow, anatase TiO2 boxes, each was enclosed by six single-crystalline TiO2 plates exposed with highly reactive {001} facets, were facilely obtained by calcining a cubic TiOF2 solid precursor at 500–600 °C. The formation of such particular nanostructures is attributed to the hard self-template restriction and the adsorption of F− ions from the TiOF2.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Yang Zhao, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 - vol. 21(Issue 20) pp:NaN7268-7268
Publication Date(Web):2011/04/15
DOI:10.1039/C1JM10745C
We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 ± 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.
Co-reporter:Qin Kuang, Tao Xu, Zhao-Xiong Xie, Shui-Chao Lin, Rong-Bin Huang and Lan-Sun Zheng
Journal of Materials Chemistry A 2009 - vol. 19(Issue 7) pp:NaN1023-1023
Publication Date(Web):2008/11/26
DOI:10.1039/B815514C
In this paper, we describe an effective two-step method for fabricating aligned SnO2nanotube arrays by using various pre-synthesized ZnO nanorod arrays as sacrificial templates. The composition and structure of as-synthesized SnO2nanotube arrays were analyzed in detail by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Because there is a special epitaxial relation between the SnO2 walls and ZnO templates, the walls building the SnO2nanotubes are highly orientated and nearly single-crystalline. Our present study provides an opportunity to investigate related physical and chemical properties and potential applications of such aligned SnO2nanotubes with nearly single-crystalline nature.
Co-reporter:Lei Zhang, Jiawei Zhang, Zhiyuan Jiang, Shuifen Xie, Mingshang Jin, Xiguang Han, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 - vol. 21(Issue 26) pp:NaN9625-9625
Publication Date(Web):2011/06/03
DOI:10.1039/C0JM04407E
Pd-based catalysts are of great interest both for fundamental research and applications. It still remains a challenge to develop reliable and versatile approaches to prepare Pd-based nanostructures with higher performance and better stability. In this article, a facile solution route has been developed to prepare Pd nanospheres, as well as Pd–Pt, Pd–Ag and Pd–Pt–Ag alloy nanospheres. SEM and TEM investigations revealed that the as-prepared nanospheres were three-dimensionally interconnected porous networks with primary nanoparticles as building blocks. The chemical composition of these nanospheres can be easily adjusted by controlling the molar ratio of precursors. Electrochemical measurements indicated that the electrocatalytic activity of these nanospheres towards formic acid oxidation depended on the composition of the nanospheres. By judiciously adjusting the composition of the Pd based alloy nanospheres, the performance of the Pd based catalysts, i.e., the onset potential of the formic acid oxidation, the corresponding peak current density and the ability to tolerate CO, can be optimized.
Co-reporter:Xiguang Han, Xi Zhou, Yaqi Jiang and Zhaoxiong Xie
Journal of Materials Chemistry A 2012 - vol. 22(Issue 21) pp:NaN10928-10928
Publication Date(Web):2012/03/22
DOI:10.1039/C2JM30843F
In this paper, we report the synthesis of spiral ZnO nanocrystals by the wet-chemical etching of pyramid ZnO nanoparticles in a solvent mixture of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that the OA in the mixed solvent acts as the etching agent. The formation of spiral ZnO nanoparticles is due to dislocations in the spiral shape surrounding the c axis formed during the growth of the pyramid ZnO nanoparticles. Moreover, the spiral ZnO nanoparticles exhibit much better gas sensing activity than the pyramid ZnO nanoparticles. Based on the structural analysis, we discuss the relationship between the surface structures and gas sensing properties.
Co-reporter:Binjie Zheng, Xue Wang, Chang Liu, Kai Tan, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2013 - vol. 1(Issue 40) pp:NaN12640-12640
Publication Date(Web):2013/08/23
DOI:10.1039/C3TA12946B
In this article, single-crystalline tetrahedral Ag3PO4 microcrystals with exposed {111} facets was successfully synthesized via a facile wet chemical method. The tetrahedral Ag3PO4 with exposed {111} facets showed the highest photocatalytic activity in visible light irradiation among the {111}, {110} and {100} facets. By DFT calculations, it is demonstrated that the surface energy of the {111} facets is higher than that of the {110} and {100} facets. It was found that the largest band gap of the Ag3PO4 {111} surface is likely to suppress the recombination of electron–hole pairs by exploring the electronic structures of the different surfaces of Ag3PO4. Meanwhile, the dispersion between the valence bands and conduction bands of the {111} surface is beneficial for the separation of photogenerated electrons and holes on the {111} surface, which further improves the photocatalytic activity of the {111} surface.
Co-reporter:Xue Wang, Chang Liu, Binjie Zheng, Yaqi Jiang, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2013 - vol. 1(Issue 2) pp:NaN287-287
Publication Date(Web):2012/10/02
DOI:10.1039/C2TA00241H
Due to the fact that crystal facets with high surface energy usually exhibit superior performance in many fields, such as catalysis, the importance of the synthesis of micro/nano-crystals with exposed high surface energy facets is becoming a hot research field. In this article, concave Cu2O microcrystals mainly enclosed by {hhl} high-index facets have been successfully prepared by reducing Cu(CH3COO)2 with glucose in the presence of sodium dodecyl sulphate (SDS). SDS was proved to be important in the formation of the concave Cu2O microcrystals. The concave degree of truncated octahedra can be controlled by adjusting the concentration of SDS. In addition, we found the reaction rate also affected the morphology of Cu2O microcrystals. Octahedron-based branched particles, truncated concave octahedra and truncated octahedra can be obtained by adjusting the concentration of glucose. In the catalytic oxidation of CO, truncated concave octahedral Cu2O enclosed by {332} high-index facets exhibited the highest catalytic activity among the high-index {332} facets, low index {111} and {100} facets, due to the existence of high density steps on {332} facets and the CO catalytic activities of the crystal facets are in the sequence: {332} > {111} > {100}.
Co-reporter:Qiaoli Chen, Yanyan Jia, Shuifen Xie and Zhaoxiong Xie
Chemical Society Reviews 2016 - vol. 45(Issue 11) pp:NaN3220-3220
Publication Date(Web):2016/04/18
DOI:10.1039/C6CS00039H
Precise engineering of noble-metal nanocrystals (NCs) is not only an important fundamental research topic, but also has great realistic significance in improving their performances required by the poor reserve and high cost of noble metals. Well-faceted noble-metal NCs with nonconvex polyhedral shapes could be promising candidates to optimize their performance and thus minimize their usage, as they may integrate a well-defined surface structure and a large surface area together, enabling them to have outstanding performance and high efficiency of atomic utilization. Moreover, undesirable aggregation and ripening phenomena could be avoided. This review provides a comprehensive summary of the unique characteristics and corresponding models of well-faceted nonconvex polyhedral noble-metal NCs by classifying the cases into four distinct types, namely the concave polyhedral structure, excavated polyhedral structure, branched structure and nanocage structure, respectively. Due to the complexity of nonconvex morphologies and the thermodynamic antipathy for the growth of nonconvex shaped NCs, we firstly demonstrate the structure characterization and synthetic methodology in detail. Subsequently, typical applications in electrocatalysis and plasmonic fields are presented to demonstrate the unique surface and morphological effects generated from the well-faceted nonconvex NCs. To promote further development in this field, the perspectives and challenges concerning well-faceted noble-metal NCs with nonconvex shapes are put forward in the end.
Co-reporter:Jiangtao Wu, Zuzhen Liao, Ting Sun, Lun-Wei Su, Jian Bi, Guangyin Fan, Daojiang Gao, Zhaoxiong Xie and Zuo-Guang Ye
Journal of Materials Chemistry A 2017 - vol. 5(Issue 16) pp:NaN4067-4067
Publication Date(Web):2017/03/28
DOI:10.1039/C7TC00512A
In ferromagnets, the magnetic moment can generally be reversed by applying a sufficiently high external magnetic field of opposite polarity. Temperature, on the other hand, is usually known to affect only the magnitude of a magnetic moment, rather than its sign or polarity (most magnets exhibit a monotonic increase in magnetization upon cooling below their magnetic phase transition temperature). As a result, temperature-induced magnetization reversal (i.e. magnetic pole inversion) remains a very rare phenomenon which lacks proper understanding and explanation because of the extreme difficulties encountered in controlling the thermodynamics of magnetization of classical metal or metal oxide magnets. Herein, we report an unusual magnetic pole inversion behaviour in multiferroic (1 − x)BiFeO3–xDyFeO3 solid solution (alloy), which can be tuned by varying the concentration of the magnetic ion Dy3+ in the solid solution. It is found that the temperature-induced magnetic pole inversion occurs in a wide composition range (x = 0.14–0.90). Moreover, for the first time in any ferrites, multiple magnetic pole inversions are observed in the solid solution compounds of high Dy3+-concentrations. Our results may provide a better understanding of the temperature- and composition-induced magnetic pole inversion and related phenomena and point to new potential applications for magnetic and multiferroic materials.
