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Active structuring of colloids through field-driven self-assembly
摘要： In recent years self-assembly has become progressively more “active”, i.e. the focus of research gradually has shifted towards field-manipulation of matter in order to form temporary states rather than creating static architectures. The desire for time-programmed control of materials certainly originates from the unmatched complexity of natural systems that orchestrate multiple components across length scales. Although artificial self-assembly still lacks control comparable to natural systems, there has been impressive progress in a concerted approach from physicists, chemists, biologists, and engineers. This review summarizes the current trend in colloidal assembly advancing from static assembly of isotropic particles towards active structuring of anisotropic particles with heterogeneous (patchy) surfaces, and ultimately, to complex behavior in dissipative dynamic systems. We focus both on the formation of static structures and on temporary states due to response to magnetic, electric, or optic stimulation. We give examples of nano- and microparticle assembly where the temporary state may adopt equilibrium order or a continuously changing dynamic pattern.
关键词： Dissipative systems,Self-assembly,Colloids,External fields,Patchy particles
更新于2025-09-10 09:29:36
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Outstanding hydrogen evolution performance of supported Pt nanoparticles: Incorporation of preformed colloids into mesoporous carbon films
摘要： Platinum is the best catalyst known so far for the hydrogen evolution reaction (HER) in acidic environments, but it is also a scarce and expensive resource. Maximizing its performance per metal atom is essential in order to reduce costs. The deposition of small Pt nanoparticles (2–3 nm) onto electrically conductive, highly accessible and stable carbon supports leads to active catalysts. However, blocking of pores and active sites by Na?on, which acts as a binding species, reduces the catalytic activity. Moreover, inaccessible Pt located in micropores diminishes an ef?cient exploitation of the noble metal. We report a new synthesis approach to ordered mesoporous carbon (OMC) coatings with preformed Pt nanoparticles. The particles are exclusively located inside the mesopores. Furthermore, no Na?on binder is needed. As a consequence, the PtNP/OMC catalyst ?lm outperforms Pt/C catalysts reported in literature particularly at high current densities. PtNP/OMC catalyst ?lms with a geometric Pt loading of 1.6 mgPt/cm2 achieve a current density of (cid:1)100 mA/cm2 at an overpotential of ca. (cid:1)70 mV.
关键词： Ordered mesoporous carbon,Noble metal colloids,Electrocatalysis,Mesoporous ?lms,Hydrogen evolution reaction
更新于2025-09-04 15:30:14
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A Simple Synthetic Approach To Prepare Silver Elongated Nanostructures: From Nanorods to Nanowires
摘要： A procedure for one-pot preparation and characterization of silver 1D nanostructures is described. The main advantages of this synthetic approach are the simplicity and reproducibility, where the size of the final product can be controlled just by changing the reaction time. This experiment is designed as a laboratory introduction to colloidal chemistry for undergraduate and graduate students; they can appreciate the role of the different reagents in a relatively complex reaction and understand the relation between the morphology of a metal at the nanoscale and some macroscopic properties, such as its visible absorption spectrum (i.e., color).
关键词： Nanotechnology,Synthesis,Second-Year Undergraduate,UV?Vis Spectroscopy,Physical Chemistry,Laboratory Instruction,Hands-On Learning/Manipulatives,First-Year Undergraduate/General,Metals,Colloids
更新于2025-09-04 15:30:14