Infrared study of chemisorption of methylamines on transition metal salts

The synergistic effect of Cd-doped and S-vacancies in CdxZn1-xIn2S4 2D nanosheets for high-performance triethylamine sensing

Ternary metal sulfides with suitable band gaps, high physicochemical stability, and unique two-dimensional (2D) nanostructures are expected to be the next-generation high-performance gas sensors following the MOS type. Doping engineering is utilized as an effective strategy to improve the semiconductor surface activity and enhance its gas-sensitive properties. In this paper, the energy band structure and surface chemical oxygen of ZnIn2S4 (ZIS) materials was tuned by selectively introducing substitutional Cd to replace the Zn sites in ZIS crystals. Meanwhile, the introduction of Cd-ions brings more abundant S vacancy defects, enhances the acid-base interactions at the interface, and pushes the extent of surface redox reactions. In addition, by combining the strong adsorption of ZIS to triethylamine, the CdxZn1-xIn2S4 nanosheets achieved highly improved sensing properties, including better response (63.38-100 ppm), enhanced selectivity (STEA/sother = 12.9), and accelerated response/recovery (4 s/32 s). The results confirm the feasibility of developing low-cost, high-performance 2D metal sulfide gas sensing materials through rational structural design and optimization.

Filamentous supramolecular structures with polyelectrolyte and cadmium sulfide

In this study, a new type of filamentous structures consisting of a generation 9 poly(amido amine) dendrimer (G9) and CdS is reported. The linearity of the interconnected dendrimers is a result of the electrostatic repulsion between the multiply charged dendrimer macroions. Structures have been investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The internal structure of the CdS-fibers reveals information on the mechanism of the fiber formation. In contrast to previous systems with smaller generation poly(propylene imine)-dendrimers, Cd(2+) is here found to be responsible for the interconnection of G9. Furthermore, more complex supramolecular structures were built by associating the CdS-dendrimer hybrid fibers with different ionic dyes, displaying the versatility of this system for future nanotechnology applications such as optoelectronics or energy conversion.

Synthesis, Photoluminescence, and Adsorption of CdS/Dendrimer Nanocomposites

CdS/dendrimer nanocomposites can be synthesized from methanolic Cd(2+) and S(2-) with amine-terminated polyamidoamine dendrimers of generation 8 (G8NH(2)) as stabilizers. By controlling the preparation conditions, nanoparticles with diameters < or = 2 nm can be obtained with a narrow size distribution. They show blue photoluminescence at approximately 450 nm. We studied the effects of various additives on the photoluminescence and elucidated its mechanism. Stable aggregates of two to three G8NH(2) molecules with several CdS nanoparticles form; the particles are located at the surface of the G8NH(2) molecules. The adsorption of the CdS/G8NH(2) nanocomposites on flat substrate surfaces is determined by the substrate chemistry. The hydrophilic nature of G8NH(2) results in weak affinity to graphite but strong affinity to hydroxy-terminated substrates such as mica, oxidized silicon wafers, and carboxylate-terminated monolayers. Patterning of nanocomposites on these hydrophilic substrates is achieved by the microcontact printing method. We propose to use only one molecule, a large dendrimer, to control the nanoparticle formation and also the immobilization of the synthesized nanoparticle/dendrimer composites.