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Water constitutes an indispensable resource for global life but remains susceptible to pollution from diverse human activities. To mitigate this issue, researchers are committed to purifying water using a variety of materials to remove harmful chemicals, such as heavy metals. Layered double hydroxides (LDHs), with their intriguing, layered structure and chemical behavior, have attained substantial attention for their effectiveness in removing heavy metal cations and various inorganic oxoanions from water. To enhance the efficiency, considerable endeavors have focused on functionalizing LDHs with different chemical species. Intercalation with metal sulfides has proven to be particularly effective, facilitating heavy metal absorption through multiple mechanisms, including ion-exchange, reductive precipitation, and surface sorption. This review concentrates on the synthesis and performance of polysulfide (Sx, x = 2–5), Mo–S, and Sn–S anion intercalated LDHs for heavy metal cations and inorganic oxoanion sorption, along with their mechanisms. Furthermore, the discussion includes prospects for expanding the chemistry of metal sulfide intercalated LDHs, with existing challenges and future outlooks. [ABSTRACT FROM AUTHOR]

We have prepared nanocrystals of MoS2 across a range of length scales by heating single crystals of the molecular precursor (NH4)2Mo3S13·H2O. Rod-shaped crystals of the polysulfide precursor retain their original morphology after heating at temperatures up to 1000 °C and undergo complete conversion to MoS2 while acting as a template for the confined formation of MoS2 nanocrystals. This solid state transformation proceeds with the release of gaseous species without blowing the crystals apart and leads to formation of pores embedded into a nanocrystalline assembly of the templated nano-MoS2. The obtained assemblies of MoS2 nanocrystals have the exact same shape of the original rod-shaped (NH4)2Mo3S13·H2O crystals indicative of a pseudomorphic shape-retentive process. Such crystal-shaped nanocrystal assemblies show electrical conductivity values similar to a bulk MoS2 single crystal with electron carrier concentration of 1.5 × 1014 cm–3 and mobility of 7 cm2/(V s). The nanocrystals of MoS2 were grown at temperatures ranging from 450 to 1000 °C, and the sizes, shapes, morphologies, and their orientations can be engineered as a function of heating rate, soaking time, and temperature. These findings suggest a unique process for constrained templated nanocrystal growth from an organized molecular precursor structure with control of bulk morphology, size distribution, and orientation of nanocrystallites. [ABSTRACT FROM AUTHOR]

We demonstrate strong iodine (I2) vapor adsorption usingMg/Al layered double hydroxide (MgAl-LDH) nanocomposites intercalatedwith polysulfide (Sx2–) groups (Sx-LDH, x = 2, 4, 6). The as-preparedLDH/polysulfide hybrid materials display highly efficient iodine captureresulting from the reducing property of the intercalated polysulfides.During adsorption, the I2molecules are reduced to I3–anions by the intercalated [Sx]2–groups that simultaneouslyare oxidized to form S8. In addition to the chemical adsorption,additional molecular I2is physically captured by the LDHcomposites. As a result of these parallel processes, and despite theirvery low BET surface areas, the iodine capture capacities of S2-LDH, S4-LDH, and S6-LDH are ∼1.32,1.52, and 1.43 g/g, respectively, with a maximum adsorption of 152%(wt %). Thermogravimetric and differential thermal analysis (TG-DTA),energy dispersive X-ray spectroscopy (EDS), and temperature-variablepowder X-ray diffraction (XRD) measurements show the resulting I3–ions that intercalated into the LDH galleryhave high thermal stability (≥350 °C). The excellent iodineadsorption performance combined with the facile preparation pointsto the Sx-LDH systems as potential superiormaterials for adsorption of radioactive iodine, a waste product ofthe nuclear power industry. [ABSTRACT FROM AUTHOR]

Sulfur cathodes in conversion reaction batteries offer high gravimetric capacity but suffer from parasitic polysulfide shuttling. We demonstrate here that transition metal chalcogels of approximate formula MoS3.4 achieve a high gravimetric capacity close to 600 mAh g-1 (close to 1000 mAh g-1 on a sulfur basis) as electrode materials for lithium-ion batteries. Transition metal chalcogels are amorphous and comprise polysulfide chains connected by inorganic linkers. The linkers appear to act as a "glue" in the electrode to prevent polysulfide shuttling. The Mo chalcogels function as electrodes in carbonate- and ether-based electrolytes, which further provides evidence of polysulfide solubility not being a limiting issue. We employ X-ray spectroscopy and operando pair distribution function techniques to elucidate the structural evolution of the electrode. Raman and X-ray photoelectron spectroscopy track the chemical moieties that arise during the anion-redox-driven processes. We find the redox state of Mo remains unchanged across the electrochemical cycling and, correspondingly, the redox is anion-driven. [ABSTRACT FROM AUTHOR]