Expanding the Repertoire of Chalcogenide Nanocrystal Networks: Ag₂Se Gels and Aerogels by Cation Exchange Reactions

Abstract

Cation exchange is shown to be a simple and efficient method to prepare nanostructured Ag(2)Se gels and aerogels from CdSe gel precursors. Treatment of CdSe wet gels with AgNO(3) yields, for the first time, Ag(2)Se gels, and these are transformed to high surface area, nanostructured aerogels by supercritical fluid drying. The striking similarity in crystallite size, morphology, and surface area characteristics between CdSe and the corresponding Ag(2)Se aerogels supports a mechanism in which the bonding within the gel network remains globally unchanged, even as the structural attributes of the primary particle components are undergoing a dramatic transformation (hexagonal CdSe to cubic Ag(2)Se). Intriguingly, the rapid exchange also enables exquisite control of composition on the macroscale; reduced concentrations of Ag(+) lead to two-component (i.e., CdSe inside, Ag(2)Se outside) heterogeneous structures of mm-cm dimensions. Overall, this methodology offers a simple approach for the generation of porous nanocrystalline metal chalcogenide networks of known or new compositions.

Transforming Hybrid Organic Inorganic Perovskites by Rapid Halide Exchange

“…Such reactions involving a variety of functional materials have been thoroughly reviewed by Clearfield 10 . More recently, multiple reactions involving cation exchange on the nanoscale have been described [11][12][13][14][15][16][17][18][19] . For instance, Beberwyck et al 21 .…”

Nanoporous Metal Foams

“…Synthetic strategies for preparing nanoporous foams of many nonmetallic substances exist, including foams (aerogels) of silica; [7][8][9] main group, transition, lanthanide, and actinide metal oxides; [10][11][12][13][14][15][16] metal chalcogenides; [17,18] metal phosphides; [19] carbon; [20,21] organic polymers; [20,22] and even carbon nanotubes. [23,24] Additionally, numerous approaches for preparing macrocellular foams of various metals exist, [25,26] such as foaming of metal alloys using bubbled gas or decomposition of metal hydrides, [27,28] investment casting, [25,29] chemical vapor deposition onto polymer foam templates, [30] and cooling of liquid metal/hydrogen solutions through their eutectic points (the GASAR process).…”

Sol-Gel Synthesis of Non-Silica Monolithic Materials

“…Hierarchically porous carbon monolith (HPCM) has been reported to be effective supports for supercapacitive materials like aniline or LiFePO 4 [10,11]. The monolithic shape can also be an advantage in luminescent [12] or superionic conductivity application [13]. Introduction of Co atoms into ZrO 2 monolithic matrices and Brilliant Blue dye molecules or Pr atoms into titania matrices, induced luminescence or enlarged the absorption spectra range [14,15,16] in the materials.…”