Advances in colloidal assembly: the design of structure and hierarchy in two and three dimensions.
TL;DR: This Review highlights the large number of methods to exploit colloidal assembly of comparably simple particles with nano- to micrometer dimensions in order to access complex structural hierarchies from nanoscopic over microscopic to macroscopic dimensions.
Abstract: This Review highlights the large number of methods to exploit colloidal assembly of comparably simple particles with nano- to micrometer dimensions in order to access complex structural hierarchies from nanoscopic over microscopic to macroscopic dimensions
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TL;DR: This review discusses efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions, and explores the unique possibilities offered by leveraging nontraditional surface chemistries and assembly environments to control superlattice structure and produce nonbulk assemblies.
Abstract: Chemical methods developed over the past two decades enable preparation of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorganic cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements experimentally attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micro...
1,376 citations
TL;DR: This review addresses recent advances made in studies of hierarchically porous materials and methods to control their structure and morphology and hopes that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information.
Abstract: Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol–gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro–macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso–macropores and meso–meso–macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and methods to control their structure and morphology.
941 citations
TL;DR: A 3D hierarchical porous catalyst architecture based on earth abundant metals Ni, Fe, and Co has been fabricated through a facile hydrothermal and electrodeposition method for efficient oxygen evolution reaction (OER) and hydrogen evolution reaction.
Abstract: A 3D hierarchical porous catalyst architecture based on earth abundant metals Ni, Fe, and Co has been fabricated through a facile hydrothermal and electrodeposition method for efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The electrode is comprised of three levels of porous structures including the bottom supermacroporous Ni foam (≈500 μm) substrate, the intermediate layer of vertically aligned macroporous NiCo2O4 nanoflakes (≈500 nm), and the topmost NiFe(oxy)hydroxide mesoporous nanosheets (≈5 nm). This hierarchical architecture is binder-free and beneficial for exposing catalytic active sites, enhancing mass transport and accelerating dissipation of gases generated during water electrolysis. Serving as an anode catalyst, the designed hierarchical electrode displays excellent OER catalytic activity with an overpotential of 340 mV to achieve a high current density of 1200 mA cm−2. Serving as a cathode catalyst, the catalyst exhibits excellent performance toward HER with a moderate overpotential of 105 mV to deliver a current density of 10 mA cm−2. Serving as both anode and cathode catalysts in a two-electrode water electrolysis system, the designed electrode only requires a potential of 1.67 V to deliver a current density of 10 mA cm−2 and exhibits excellent durability in prolonged bulk alkaline water electrolysis.
518 citations
TL;DR: A microfluidic chip with self-assembled 3D herringbone nanopatterns detects, with high sensitivity and specificity, tumour-associated exosomes in few-microlitre plasma samples from patients, and suggests exosomal folate receptor alpha as a potential biomarker for early detection and progression monitoring of ovarian cancer.
Abstract: The performance of current microfluidic methods for exosome detection is constrained by boundary conditions, as well as fundamental limits to microscale mass transfer and interfacial exosome binding. Here, we show that a microfluidic chip designed with self-assembled three-dimensional herringbone nanopatterns can detect low levels of tumour-associated exosomes in plasma (10 exosomes μl−1, or approximately 200 vesicles per 20 μl of spiked sample) that would otherwise be undetectable by standard microfluidic systems for biosensing. The nanopatterns promote microscale mass transfer, increase surface area and probe density to enhance the efficiency and speed of exosome binding, and permit drainage of the boundary fluid to reduce near-surface hydrodynamic resistance, thus promoting particle–surface interactions for exosome binding. We used the device for the detection—in 2 μl plasma samples from 20 ovarian cancer patients and 10 age-matched controls—of exosome subpopulations expressing CD24, epithelial cell adhesion molecule and folate receptor alpha proteins, and suggest exosomal folate receptor alpha as a potential biomarker for early detection and progression monitoring of ovarian cancer. The nanolithography-free nanopatterned device should facilitate the use of liquid biopsies for cancer diagnosis. A microfluidic chip with self-assembled 3D herringbone nanopatterns detects, with high sensitivity and specificity, tumour-associated exosomes in few-microlitre plasma samples from patients.
309 citations
TL;DR: This review summarizes recent developments in the field of colloid-based porous materials, including principles for their design, fabrication, and applications, with a particular focus on structural features and materials' properties that enable these applications.
Abstract: Nature evolved a variety of hierarchical structures that produce sophisticated functions. Inspired by these natural materials, colloidal self-assembly provides a convenient way to produce structures from simple building blocks with a variety of complex functions beyond those found in nature. In particular, colloid-based porous materials (CBPM) can be made from a wide variety of materials. The internal structure of CBPM also has several key attributes, namely porosity on a sub-micrometer length scale, interconnectivity of these pores, and a controllable degree of order. The combination of structure and composition allow CBPM to attain properties important for modern applications such as photonic inks, colorimetric sensors, self-cleaning surfaces, water purification systems, or batteries. This review summarizes recent developments in the field of CBPM, including principles for their design, fabrication, and applications, with a particular focus on structural features and materials' properties that enable these applications. We begin with a short introduction to the wide variety of patterns that can be generated by colloidal self-assembly and templating processes. We then discuss different applications of such structures, focusing on optics, wetting, sensing, catalysis, and electrodes. Different fields of applications require different properties, yet the modularity of the assembly process of CBPM provides a high degree of tunability and tailorability in composition and structure. We examine the significance of properties such as structure, composition, and degree of order on the materials' functions and use, as well as trends in and future directions for the development of CBPM.
240 citations
References
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TL;DR: In this article, a system of chemical reactions has been developed which permits the controlled growth of spherical silica particles of uniform size by means of hydrolysis of alkyl silicates and subsequent condensation of silicic acid in alcoholic solutions.
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TL;DR: In this article, the authors focus on the properties of quantum dots and their ability to join the dots into complex assemblies creates many opportunities for scientific discovery, such as the ability of joining the dots to complex assemblies.
Abstract: Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.
10,737 citations
TL;DR: In el marco del Proyecto subvencionado by the Fundación Antorchas (FAN) as discussed by the authors, el material was digitalizado, e.g., en la Biblioteca del Departamento de Fisica de la Facultad de Ciencias Exactas de la Universidad Nacional de La Plata.
Abstract: Este material fue digitalizado en el marco del Proyecto subvencionado por la Fundacion Antorchas y se encuentra en la Biblioteca del Departamento de Fisica de la Facultad de Ciencias Exactas de la Universidad Nacional de La Plata.
6,971 citations