Special Issue "Mesocrystals and Hierarchical Structures"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: closed (30 September 2016)

Special Issue Editor

Guest Editor
Dr. Monica Distaso

Institute of Particle Technology, FAU Erlangen Nürnberg, Erlangen, Germany
Website | E-Mail
Interests: classical and non-classical crystallization; mesocrystals and hierarchical materials; design of nanocomposite materials; optical properties; design of multicomponent nanoparticles (Cu2ZnSnS4, CuInS(e)2) for photovoltaic applications; activation of small molecules (carbon dioxide, dimethyl carbonate); catalysis

Special Issue Information

Dear Colleagues,

This Special Issue aims to promote an interdisciplinary exchange on the latest development in the field of design, characterization, and applications of hierarchical materials, including mesocrystals and colloidal arrays. In the last 10 years, there has been a great interest in the scientific community for the design of nanoassemblies of primary particles by oriented attachment. The understanding of the formation mechanism has received a breakthrough from the development of in situ techniques. Current approaches include mathematical simulations to shed light on the interaction forces among primary particles or model the properties of materials to understand their intimate structure-function relation. Finally, the combination of multiple length scales in a single crystal envisages novel applications in nanotechnology.

The Special Issue on “Mesocrystals and Hierarchical Structures” is intended to provide an interdisciplinary platform for critically reviewing the design, formation mechanism, physical- chemical properties of the superstructures, and their emerging applications as catalysts, light absorbers in solar cells, sensors, and pigments, to mention only a few. Scientists working in both experimental and theoretical disciplines are invited to submit original contributions.

Dr. Monica Distaso
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • synthesis and characterization of mesocrystals and hierarchical structures;
  • colloidal arrays
  • in situ monitoring of particle formation
  • oriented attachment
  • numerical simulations
  • catalysis
  • porosity
  • opto-electronic applications
  • nano-medicine

Published Papers (10 papers)

View options order results:
result details:
Displaying articles 1-10
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Induced Mesocrystal-Formation, Hydrothermal Growth and Magnetic Properties of α-Fe2O3 Nanoparticles in Salt-Rich Aqueous Solutions
Crystals 2017, 7(8), 248; doi:10.3390/cryst7080248
Received: 15 June 2017 / Revised: 19 July 2017 / Accepted: 21 July 2017 / Published: 8 August 2017
PDF Full-text (13693 KB) | HTML Full-text | XML Full-text
Abstract
Iron oxide nanoparticles are widely prevalent in our aqueous environment (e.g., streams, seawater, hydrothermal vents). Their aggregation and crystal growth depend on their chemical surroundings, for instance just a change in pH or salt concentration can greatly affect this. In turn this influences
[...] Read more.
Iron oxide nanoparticles are widely prevalent in our aqueous environment (e.g., streams, seawater, hydrothermal vents). Their aggregation and crystal growth depend on their chemical surroundings, for instance just a change in pH or salt concentration can greatly affect this. In turn this influences their properties, mobility, fate, and environmental impact. We studied the growth of α-Fe2O3 (hematite), starting from 8 nm hematite particles in weakly acidic (HNO3) aqueous suspension with different states of particle aggregation, using salt (NaCl and NaH2PO4) to control their initial aggregation state. The samples were then subject to hydrothermal treatment at 100–140 °C. We followed the development in aggregation state and particle size by dynamic light scattering, X-ray diffraction, small angle neutron scattering and transmission electron microscopy, and the magnetic properties by Mössbauer spectroscopy. The addition of NaCl and NaH2PO4 both led to aggregation, but NaCl led to linear chains of hematite nanoparticles (oriented parallel to their hexagonal c-axis), such that the crystalline lattice planes of neighboring hematite particles were aligned. However, despite this oriented alignment, the particles did not merge and coalesce. Rather they remained stable as mesocrystals until heat-treated. In turn, the addition of NaCl significantly increases the rate of growth during hydrothermal treatment, probably because the nanoparticles, due to the chain formation, are already aligned and in close proximity. With hydrothermal treatment, the magnetic properties of the particles transform from those characteristic of small (aggregated) hematite nanoparticles to those of particles with more bulk-like properties such as Morin transition and suppression of superparamagnetic relaxation, in correspondence with the growth of particle size. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Figure 1

Open AccessArticle Reversed Crystal Growth of Calcite in Naturally Occurring Travertine Crust
Crystals 2017, 7(2), 36; doi:10.3390/cryst7020036
Received: 30 August 2016 / Revised: 19 January 2017 / Accepted: 22 January 2017 / Published: 28 January 2017
PDF Full-text (3876 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A microstructural investigation by electron microscopy on a travertine specimen collected from Munigou National Park, Sichuan Province, China revealed evidence of a non-classical reversed crystal growth route previously only discovered in synthetic materials. Examination of the travertine specimen suggests that the presence of
[...] Read more.
A microstructural investigation by electron microscopy on a travertine specimen collected from Munigou National Park, Sichuan Province, China revealed evidence of a non-classical reversed crystal growth route previously only discovered in synthetic materials. Examination of the travertine specimen suggests that the presence of organic matter initiates the oriented aggregation of calcite nanocrystallites. Surface re-crystallisation of the aggregates leads to a single crystalline rhombohedral shell with a polycrystalline core. This core-shell structure carries a strong resemblance to synthetic calcite prepared in the presence of chitosan, where the growth of calcite was found to follow the so-called reversed crystal growth process. It is proposed that the similar roles of biomolecules in naturally occurring travertine and chitosan in the synthetic system are based on their isoelectric points and the polymerizable property of long chain chemical structures. This study is important so that the structural similarities between naturally occurring biominerals and biomimetic materials can be further understood. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Figure 1

Open AccessArticle Applicability of Effective Medium Approximations to Modelling of Mesocrystal Optical Properties
Crystals 2017, 7(1), 1; doi:10.3390/cryst7010001
Received: 19 October 2016 / Revised: 12 December 2016 / Accepted: 20 December 2016 / Published: 22 December 2016
Cited by 3 | PDF Full-text (1843 KB) | HTML Full-text | XML Full-text
Abstract
Rigorous superposition T-matrix method is used to compute light interaction with mesocrystalline structures. The results are used to validate the applicability of effective medium theories for computing the effective optical constants of mesocrystal structures composed of optically isotropic materials. It is demonstrated that
[...] Read more.
Rigorous superposition T-matrix method is used to compute light interaction with mesocrystalline structures. The results are used to validate the applicability of effective medium theories for computing the effective optical constants of mesocrystal structures composed of optically isotropic materials. It is demonstrated that the Maxwell-Garnett theory can fit the rigorous simulation results with an average accuracy of 2%. The thus obtained refractive indexes can be used with any electromagnetic simulation software to represent the response of mesocrystals composed of optically small primary particles arranged into a cubic type lattice structures. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Figure 1

Open AccessArticle In Situ Studies on Phase Transitions of Tris(acetylacetonato)-Aluminum(III) Al(acac)3
Crystals 2016, 6(12), 157; doi:10.3390/cryst6120157
Received: 21 October 2016 / Revised: 18 November 2016 / Accepted: 22 November 2016 / Published: 28 November 2016
Cited by 4 | PDF Full-text (2539 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In situ investigations on the nucleation and crystallization processes are essential for understanding of the formation of solids. Hence, the results of such experiments are prerequisites for the rational synthesis of solid materials. The in situ approach allows the detection of precursors, intermediates,
[...] Read more.
In situ investigations on the nucleation and crystallization processes are essential for understanding of the formation of solids. Hence, the results of such experiments are prerequisites for the rational synthesis of solid materials. The in situ approach allows the detection of precursors, intermediates, and/or polymorphs, which are mainly missed in applying ex situ experiments. With a newly developed crystallization cell, simultaneous in situ experiments with X-ray diffraction (XRD) and luminescence analysis are possible, also monitoring several other reaction parameters. Here, the crystallization of the model system tris(acetylacetonato)-aluminum(III) Al(acac)3 was investigated. In the time-resolved in situ XRD patterns, two polymorphs of Al(acac)3, the α- and the γ-phase, were detected at room temperature and the influence of the pH value onto the product formation was studied. Moreover, changes in the emission of Al(acac)3 and the light transmission of the solution facilitated monitoring the reaction by in situ luminescence. The first results demonstrate the potential of the cell to be advantageous for controlling and monitoring several reaction parameters during the crystallization process. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Open AccessArticle Controllable Hydrothermal Conversion from Ni-Co-Mn Carbonate Nanoparticles to Microspheres
Crystals 2016, 6(11), 156; doi:10.3390/cryst6110156
Received: 2 October 2016 / Revised: 17 November 2016 / Accepted: 18 November 2016 / Published: 23 November 2016
PDF Full-text (10750 KB) | HTML Full-text | XML Full-text
Abstract
Starting from Ni-Co-Mn carbonate nanoparticles prepared by microreaction technology, uniform spherical particles of Ni1/3Co1/3Mn1/3CO3 with a size of 3–4 μm were obtained by a controllable hydrothermal conversion with the addition of (NH4)2CO
[...] Read more.
Starting from Ni-Co-Mn carbonate nanoparticles prepared by microreaction technology, uniform spherical particles of Ni1/3Co1/3Mn1/3CO3 with a size of 3–4 μm were obtained by a controllable hydrothermal conversion with the addition of (NH4)2CO3. Based on characterizations on the evolution of morphology and composition with hydrothermal treatment time, we clarified the mechanism of this novel method as a dissolution-recrystallization process, as well as the effects of (NH4)2CO3 concentration on the morphology and composition of particles. By changing concentrations and the ratio of the starting materials for nano-precipitation preparation, we achieved monotonic regulation on the size of the spherical particles, and the synthesis of Ni0.4Co0.2Mn0.4CO3 and Ni0.5Co0.2Mn0.3CO3, respectively. In addition, the spherical particles with a core-shell structure were preliminarily verified to be available by introducing nano-precipitates with different compositions in the hydrothermal treatment in sequence. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Open AccessArticle A Hierarchically Micro-Meso-Macroporous Zeolite CaA for Methanol Conversion to Dimethyl Ether
Crystals 2016, 6(11), 155; doi:10.3390/cryst6110155
Received: 27 September 2016 / Revised: 8 November 2016 / Accepted: 17 November 2016 / Published: 23 November 2016
Cited by 1 | PDF Full-text (2099 KB) | HTML Full-text | XML Full-text
Abstract
A hierarchical zeolite CaA with microporous, mesoporous and macroporous structure was hydrothermally synthesized by a ”Bond-Blocking” method using organo-functionalized mesoporous silica (MS) as a silica source. The characterization by XRD, SEM/TEM and N2 adsorption/desorption techniques showed that the prepared material had well-crystalline
[...] Read more.
A hierarchical zeolite CaA with microporous, mesoporous and macroporous structure was hydrothermally synthesized by a ”Bond-Blocking” method using organo-functionalized mesoporous silica (MS) as a silica source. The characterization by XRD, SEM/TEM and N2 adsorption/desorption techniques showed that the prepared material had well-crystalline zeolite Linde Type A (LTA) topological structure, microspherical particle morphologies, and hierarchically intracrystalline micro-meso-macropores structure. With the Bond-Blocking principle, the external surface area and macro-mesoporosity of the hierarchical zeolite CaA can be adjusted by varying the organo-functionalized degree of the mesoporous silica surface. Similarly, the distribution of the micro-meso-macroporous structure in the zeolite CaA can be controlled purposely. Compared with the conventional microporous zeolite CaA, the hierarchical zeolite CaA as a catalyst in the conversion of methanol to dimethyl ether (DME), exhibited complete DME selectivity and stable catalytic activity with high methanol conversion. The catalytic performances of the hierarchical zeolite CaA results clearly from the micro-meso-macroporous structure, improving diffusion properties, favoring the access to the active surface and avoiding secondary reactions (no hydrocarbon products were detected after 3 h of reaction). Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Open AccessArticle Facile Synthesis, Characterization, and Visible-light Photocatalytic Activities of 3D Hierarchical Bi2S3 Architectures Assembled by Nanoplatelets
Crystals 2016, 6(11), 140; doi:10.3390/cryst6110140
Received: 8 August 2016 / Revised: 18 October 2016 / Accepted: 24 October 2016 / Published: 31 October 2016
Cited by 4 | PDF Full-text (12568 KB) | HTML Full-text | XML Full-text
Abstract
3D hierarchical Bi2S3 architectures have been successfully synthesized via a simple and effective hydrothermal process. The as-prepared Bi2S3 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption- desorption isotherms,
[...] Read more.
3D hierarchical Bi2S3 architectures have been successfully synthesized via a simple and effective hydrothermal process. The as-prepared Bi2S3 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption- desorption isotherms, and UV-vis diffuse reflectance spectrum (DRS). The observation of field emission scanning electron microscope (FESEM) images showed that numerous nanoplatelets are randomly arranged and interconnected with each other, which are assembled into 3D hierarchical Bi2S3 architectures. The photocatalytic activity of the as-prepared Bi2S3 samples was evaluated by the degradation of Rhodamine B (RhB) under visible light irradiation. The effect of hydrothermal temperature, reaction time, pH value and shape on the photocatalytic efficiency of the as-prepared Bi2S3 samples was investigated. The results showed that 3D hierarchical Bi2S3 architectures prepared at 165 °C for 12 h at a pH of 2.4 exhibits high photocatalytic efficiency, which could be ascribed to the synergetic effect of the shape, surface area, crystallinity, band gap and crystalline size. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Figure 1

Open AccessArticle Effect of HNO3 Concentration on the Morphologies and Properties of Bi2WO6 Photocatalyst Synthesized by a Hydrothermal Method
Crystals 2016, 6(7), 75; doi:10.3390/cryst6070075
Received: 10 May 2016 / Revised: 27 June 2016 / Accepted: 28 June 2016 / Published: 20 July 2016
Cited by 4 | PDF Full-text (4644 KB) | HTML Full-text | XML Full-text
Abstract
Bi2WO6 samples were prepared by a hydrothermal method using Bi(NO3)3·5H2O and Na2WO4·2H2O as raw materials. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Raman and Brunauer–Emmett–Teller (BET) were
[...] Read more.
Bi2WO6 samples were prepared by a hydrothermal method using Bi(NO3)3·5H2O and Na2WO4·2H2O as raw materials. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Raman and Brunauer–Emmett–Teller (BET) were employed for sample characterization. The photocatalytic activity of the samples was evaluated by the degradation of Rhodamine B under visible-light irradiation. The photocatalytic activity of Bi2WO6, as well as the effect of varying HNO3 concentrations on the morphologies of Bi2WO6, was investigated. The HNO3 concentration significantly affected the structure and morphology of the Bi2WO6. The photocatalytic performance varied with the structure, morphology, and surface area of the Bi2WO6 samples. The results indicated that the H10 sample exhibits uniform morphology and excellent photocatalytic performance; using this sample, the degradation of Rhodamine B reached 96% in 90 min under visible-light irradiation. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Review

Jump to: Research

Open AccessReview Mesocrystals: Past, Presence, Future
Crystals 2017, 7(7), 207; doi:10.3390/cryst7070207
Received: 15 June 2017 / Revised: 2 July 2017 / Accepted: 4 July 2017 / Published: 9 July 2017
PDF Full-text (5201 KB) | HTML Full-text | XML Full-text
Abstract
In this review, we briefly summarize the history of mesocrystal research. We introduce the current structural definition of mesocrystals and discuss the appropriate base for the classification of mesocrystals and their relations with other classes of solid state materials in terms of their
[...] Read more.
In this review, we briefly summarize the history of mesocrystal research. We introduce the current structural definition of mesocrystals and discuss the appropriate base for the classification of mesocrystals and their relations with other classes of solid state materials in terms of their structure. Building up on this, we comment on the problems in mesocrystal research both fundamental and methodological. Additionally, we make the short overview of the mesocrystal formation principles and synthetic routes used for their fabrications. As an outlook into the future, we highlight the most notable trends in mesocrystal research and developments. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Figure 1

Open AccessReview A Review on the Fabrication of Hierarchical ZnO Nanostructures for Photocatalysis Application
Crystals 2016, 6(11), 148; doi:10.3390/cryst6110148
Received: 20 October 2016 / Revised: 6 November 2016 / Accepted: 8 November 2016 / Published: 16 November 2016
Cited by 5 | PDF Full-text (10505 KB) | HTML Full-text | XML Full-text
Abstract
Semiconductor photocatalysis provides potential solutions for many energy and environmental-related issues. Recently, various semiconductors with hierarchical nanostructures have been fabricated to achieve efficient photocatalysts owing to their multiple advantages, such as high surface area, porous structures, as well as enhanced light harvesting. ZnO
[...] Read more.
Semiconductor photocatalysis provides potential solutions for many energy and environmental-related issues. Recently, various semiconductors with hierarchical nanostructures have been fabricated to achieve efficient photocatalysts owing to their multiple advantages, such as high surface area, porous structures, as well as enhanced light harvesting. ZnO has been widely investigated and considered as the most promising alternative photocatalyst to TiO2. Herein, we present a review on the fabrication methods, growth mechanisms and photocatalytic applications of hierarchical ZnO nanostructures. Various synthetic strategies and growth mechanisms, including multistep sequential growth routes, template-based synthesis, template-free self-organization and precursor or self-templating strategies, are highlighted. In addition, the fabrication of multicomponent ZnO-based nanocomposites with hierarchical structures is also included. Finally, the application of hierarchical ZnO nanostructures and nanocomposites in typical photocatalytic reactions, such as pollutant degradation and H2 evolution, is reviewed. Full article
(This article belongs to the Special Issue Mesocrystals and Hierarchical Structures)
Figures

Back to Top