Engineering Strength, Porosity, and Emission Intensity of Nanostructured CdSe Networks by Altering the Building-Block Shape

Abstract

The effect of primary particle shape on the porosity, mechanical strength, and luminescence intensity of metal chalcogenide aerogels was probed by comparison of CdSe aerogels prepared from spherical and rod-shaped particles. Rod-shaped particles yield aerogels with polymeric morphologies in contrast to the colloidal morphology obtained from spherical particles. Relative to the colloidal analogues, the polymeric CdSe aerogels exhibit twice the surface area, a doubling of the complex viscosity for 5 wt % aerogel-PDMS composites, and a 25-fold increase in emission intensity. Altering the shape of the building block from which nanostructured networks are assembled is an effective way to tune the basic properties of metal chalcogenide semiconducting aerogels.

Modern Inorganic Aerogels

“…[56,57] Forinstance,aerogels made from CdSe nanorods showed a2 5times more intense luminescence compared to that for aerogels obtained from CdSe nanoparticles.F urthermore,g el structures obtained from rods or branched nanoparticles show superior mechanical strength and porosity compared to gels from quantum dots.This is mainly attributed to the polymer-like structure of these materials.C hanging the density of CdSe gels has been used to tune their optical band gap. [56,57] Forinstance,aerogels made from CdSe nanorods showed a2 5times more intense luminescence compared to that for aerogels obtained from CdSe nanoparticles.F urthermore,g el structures obtained from rods or branched nanoparticles show superior mechanical strength and porosity compared to gels from quantum dots.This is mainly attributed to the polymer-like structure of these materials.C hanging the density of CdSe gels has been used to tune their optical band gap.…”

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

“…[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.…”

A Special Material or a New State of Matter: A Review and Reconsideration of the Aerogel

“…In addition, in 2007, Brock’s group reported the reaction mechanism in detail [116]. After that, various chalcogenide aerogels were reported including direct-synthesized aerogels and ion-exchanged aerogels [29,30,31,32,117,118,119]. …”

“…After entering the 21st century, aerogel category was booming. Lots of novel non-silica oxide aerogels [18,19,20,21,22,23,24,25,26,27,28], chalcogenide aerogels [29,30,31,32,33,34,35], gradient aerogels (from 90 s) and other aerogel composites sprang up one after another [36,37,38,39]. Recently, novel aerogels such as carbon nanotube (CNT) aerogel [40,41,42,43], graphene aerogel [44,45,46,47,48,49,50], silicon aerogel and carbide (or carbonitride) aerogel were added into the aerogel community continually [51,52,53,54,55].…”