CdS aerogels: Effect of concentration and primary particle size on surface area and opto-electronic properties

Mohanan, Jaya L.; Brock, Stephanie L.

doi:10.1007/s10971-006-9049-4

Cited by 24 publications

(13 citation statements)

References 21 publications

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“…One major drawback of the conventional aerogel synthesis is that the synthetic route is a multistep procedure, because the colloidal NPs first need to be destabilized in a controlled way in order to form hydro‐ or alcogels, and only once these superstructures have formed they can be transformed to aerogels by supercritical drying . The nano‐ and microscopic morphologies of the superstructure are strongly dependent on the destabilization step which means that solvents, surfactants, zeta potential, and especially the type of destabilizing procedure/agent are critical parameters for the nanoscopic morphology of the resulting gels, so that the chemical gelation procedure needs to be adjusted for each system . The synthesis of aerogels can be time consuming, complex, and expensive.…”

Section: Figurementioning

confidence: 99%

“…[1,2,12] Thenano-and microscopic morphologies of the superstructure are strongly dependent on the destabilization step which means that solvents,s urfactants,z eta potential, and especially the type of destabilizing procedure/ agent are critical parameters for the nanoscopic morphology of the resulting gels,s ot hat the chemical gelation procedure needs to be adjusted for each system. [13][14][15][16][17] Thes ynthesis of aerogels can be time consuming,c omplex, and expensive. Furthermore,c onventional lyogelation methods are frequently accompanied by syneresis effects,s ot hat it is very difficult to synthesize special external shapes,w hich in turn would be of interest for possible applications.H erein, we propose an alternative assembly method (see Figure 1) based on aphysical process.Byfreezing aqueous NP colloids in situ and subsequent freeze-drying,m onolithic aerogels are obtained that consist of as elf-supported network of thin platelets building up the gel network, the platelets being mostly 2D assemblies of the NP building blocks.T he advantage of our strategy is the suitability for many different NP systems,s ince there is no chemical selectivity.U nder optimum conditions,the volume and shape of the liquid equal the volume and shape of the resulting aerogel.…”

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Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions

et al. 2015

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A versatile method to fabricate self-supported aerogels of nanoparticle (NP) building blocks is presented. This approach is based on freezing colloidal NPs and subsequent freeze drying. This means that the colloidal NPs are directly transferred into dry aerogel-like monolithic superstructures without previous lyogelation as would be the case for conventional aerogel and cryogel fabrication methods. The assembly process, based on a physical concept, is highly versatile: cryogelation is applicable for noble metal, metal oxide, and semiconductor NPs, and no impact of the surface chemistry or NP shape on the resulting morphology is observed. Under optimized conditions the shape and volume of the liquid equal those of the resulting aerogels. Also, we show that thin and homogeneous films of the material can be obtained. Furthermore, the physical properties of the aerogels are discussed.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions

et al. 2015

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“…Dabei ist die nano‐ und mikroskopische Morphologie sehr stark von der Destabilisierung abhängig, was bedeutet, dass Lösungsmittel, oberflächenwirksame Stoffe, ζ‐Potential und besonders die Art der Destabilisierung bzw. das Destabilisierungsmittel erheblichen Einfluss auf die nanoskopische Morphologie besitzen und daher für jedes System die Gelierung angepasst und optimiert werden muss . Die Synthese von Aerogelen kann daher zeitraubend, komplex und teuer sein.…”

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Universelle Methode zur Herstellung von Aerogelen aus kolloidalen Nanopartikellösungen durch Einfrieren und anschließendes Gefriertrocknen

et al. 2015

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In dieser Zuschrift wird über eine universelle Methode zur Herstellung von selbsttragenden Aerogelen aus kolloidalen Nanopartikeln (NP) berichtet. Dafür werden die NP eingefroren und anschließend gefriergetrocknet. Das bedeutet, dass die kolloidalen NP ohne vorherige Gelierung (wie bisher bei herkömmlichen Aero‐ und Kryogel‐Verfahren üblich) direkt in trockene, aerogelähnliche monolithische Überstrukturen überführt werden können. Die Anordnung der NP zu einer Überstruktur ist ein rein physikalischer Prozess und dadurch vielfältig einsetzbar, was bedeutet, dass die Kryogelierung auf Edelmetall‐, Metalloxid‐ und Halbleiter‐NP angewendet werden kann. Die Kryogelierung beeinflusst die Oberflächenchemie oder die NP‐Form in der entstehenden Morphologie dabei nicht. Unter idealen Bedingungen sind auch die Volumina und die Formen von gefrorenem NP‐Kolloid und Aerogel gleich groß. Dies ermöglicht es, mit der Methode dünne, gleichmäßige Aerogelfilme und andere Geometrien von Aerogelmonolithen herzustellen. Abschließend werden die physikochemischen Eigenschaften der Aerogele diskutiert.

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“…S. L. Brock and co-workers [19][20][21][22] have expanded this work to fabricate unsupported CdS aerogels in which CdS is three-dimensionally linked together into a solid architecture. However, these materials do not appear to be highly transparent to be useful as a volumetric display medium.…”

Section: Quantum Dot Dispersion In Silica Aerogelmentioning

confidence: 99%

Quantum dot dispersions in aerogels: a new material for true volumetric color displays

2010

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The true volumetric displays project a 3D image within a cube viewable from most of its sides thus providing the ultimate physiological depth cues for countless applications. The ultra-light and highly transparent aerogels may provide the best optical medium for these displays as they can be easily fabricated in the form of a large-volume, low-scattering bulk material. On the other hand, the semiconductor nanocrystals (quantum dots, QDs) are a remarkable fluorescent material with optical properties superior to those of conventional materials. QDs dispersed in aerogels hold a promise to become the most efficient display material for volumetric 3D displays. The true volumetric displays described in the literature are built around the concept of two beams exciting the fluorescent material in their intersection. However, the optical properties of QDs are quite different from these of the fluorescent materials proposed for intersecting-beams displays and it may not be feasible to build such displays using QDs. Instead, we are proposing the use of a single focused infrared laser beam to excite a nanostructured material for volumetric color displays consisting of QDs dispersed in a transparent silica aerogel matrix. Presented are the theory and modeling results proving the feasibility of this approach.

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CdS aerogels: Effect of concentration and primary particle size on surface area and opto-electronic properties

Cited by 24 publications

References 21 publications

Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions

Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions

Universelle Methode zur Herstellung von Aerogelen aus kolloidalen Nanopartikellösungen durch Einfrieren und anschließendes Gefriertrocknen

Quantum dot dispersions in aerogels: a new material for true volumetric color displays

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