Formation of Cadmium Sulfide and Zinc Sulfide Mixture in the Interlayer Space of Montmorillonite

Abstract

Cadmium sulfide and zinc sulfide (CdS and ZnS) were incorporated in sodium and cetyltrimethylammonium montmorillonites by the precipitation of sulfides from soluble metal sources in the presence of montmorillonites. The resulting hybrids were characterized by XRD, themogravimetric/differential thermal analysis (TG‐DTA), TEM, Raman spectroscopy, and UV/Vis and photoluminescence spectroscopy. The absorption onsets owing to CdS and ZnS in cetyltrimethylammonium‐montmorillonite appeared in a shorter wavelength region (311–520 nm) relative to that (309–484 nm) of the two semiconductors in sodium montmorillonite, thus reflecting the difference in the particle sizes of CdS and ZnS in the hybrids. The appearance of the broad emission bands combined with the bands centered at 469, 451, 440, and 431 nm owing to CdS and ZnS were attributed to the existence of both CdS and ZnS in the products. The difference in the emission intensity of the hybrids is discussed in terms of the role of the cetyltrimethylammonium cation. The unique optical properties of the two products were thought to occur through the interactions of sulfides with their environment (montmorillonite and cetyltrimethylammonium cation).

Preparation of metal sulfide mixtures in montmorillonite by solid–solid reactions

“…The photoluminescence intensities of the products were slightly increased after the storage up to seventeen months corresponding to the blue shift of the absorption onsets of the stored products, attributing to the decrease in the particle size of the metal sulfide mixtures (Sun et al, 2013). In comparison with the photoluminescence intensity of the same product prepared by solid-liquid reactions (Kabilaphat et al, 2015), the PL intensities of the product prepared by solid-solid reaction was two times weaker. This was consistent with the slight increase of the particle size and the shift of absorption onset mentioned above.…”

“…It was reported that CdS and ZnS intercalated in the different interlayer spaces (segregation) (Scheme 1b, Kabilaphat et al, 2015), the aggregation that occurred between the homogeneous solids (ZnS/ ZnS and CdS/CdS) should be better than that of the heterogonous ones (MnS/ZnS and MnS/CdS) that MnS and ZnS, or CdS incorporated as a mixture in each interlayer space (integration) (Scheme 1a). However, in comparison with the average particle size of metal sulfide mixture in the similar system prepared by solid-liquid reactions (ZnS/CdS@Mt (2.50 nm), Kabilaphat et al, 2015), the intercalated metal sulfides obtained by solid-solid reactions were aggregated more and gave the larger size and wider size distribution (Table 1), while, that synthesized by solid-liquid reactions was rather dispersed in the interlayer spaces of montmorillonite. This was thought to be caused by the effect of the aqueous medium that allowed the metal ions dispersed well in the interlayer spaces during intercalation process.…”

“…Because the solid-state intercalation sometimes gave the products with different chemical and physical properties compared with those prepared by a conventional solid-liquid reaction, here, the synthesis of MnS and ZnS, or CdS, as well as ZnS and CdS in montmorillonite by solid-solid reactions is examined. Metal sulfide mixtures (MnS and ZnS, or CdS, as well as ZnS and CdS) prepared in the interlayer spaces of organically modified and pristine montmorillonites by solid-liquid reactions showed the improvement in energy band gap and luminescent properties due to quantum size effect (Kabilaphat et al, 2015). The solid-state prepared products may show differences in structure and properties, which expectedly made the worthy materials for applying as optical devices, photocatalyst and so on.…”

Control of particle growth and enhancement of photoluminescence, adsorption efficiency, and photocatalytic activity for zinc sulfide and cadmium sulfide using CoAl-layered double hydroxide system

“…2d), therefore, the obtained nanoparticles of ZnS or CdS with orderly particle size distribution could con rm the intercalation in the interlayer space. The distinct sizes of the intercalated ZnS and CdS nanoparticles might be because of the difference in their bonding lengths of ZnS (∼ 258 pm) and CdS (∼ 279 pm) that affected on the particle growth (Kabilaphat et al 2015). Considering the expansion of the interlayer space in Table 1, the intercalated nanoparticles were plate-or disk-like shape based on the diameter size of 2.61 nm for ZnS/CoAl-LDH@DS and of 3.29 nm for CdS/CoAl-LDH@DS, and their thickness about 0.4 nm, which arranged parallel to LDH nanosheet together with few interlayer CO 3 2− ions.…”

Preparation of quantum dots-montmorillonite nanocomposites with strong photoluminescence for light-emitting diodes

“…19,20 By intercalating QDs into MMT, the QDs/MMT nanocomposites with various compositions are recently demonstrated. [21][22][23][24][25][26][27] Due to the stable chemical and PL properties, the QDs/MMT nanocomposites have been successfully used for enhanced latent ngerprint detection. 28 However, the utilization of QDs/MMT nanocomposites as the color conversion layer for LEDs has never been attempted.…”