Chalcogels are three-dimensional porous networks with unique applications in catalysis, gas adsorption, energy storage, and environmental remediation. Here, we demonstrate the efficacy of antimony sulfide chalcogels for the selective sequestration of organic dyes from aqueous solutions. The chalcogels exhibit high adsorption capacities for the dyes rhodamine B (RhB), methylene blue (MB), and methyl violet (MV), however, display poor adsorption capacity for the orange G (OG) dye. Lewis-basicity of chalcogel's network is responsible for selective affinity toward RhB, MB, and MV, thus favoring the capture of electron accepting dyes through Lewis acid-base interactions. The adsorption kinetics obeys the pseudo second-order model rather than the pseudo first-order model, and the equilibrium adsorption data fits well to the Langmuir isotherm equation. Dye removal efficiencies up to 99% are achieved in 30 min for an initial concentration of 25 mg/100 mL of the aqueous dye solutions. Langmuir adsorption capacities are found to be 442, 303, and 210 mg/g for RhB, MB, and MV, respectively. Using the selective adsorption behavior of antimony sulfide chalcogels, separation of mixed dyes MB/OG (RhB/OG) is realized through molecular filtration. These results suggest that chalcogels are potential candidates for the treatment of industrial effluents, thus providing a new platform for molecular filtration of organic dyes and other organic molecules.

Thermal conductivity is a crucial parameter for managing exothermal gas adsorption in metal organic frameworks (MOFs), but experimental studies have been limited. In this work, the thermal conductivity of a zeolitic imidazolate framework ZIF-8 was experimentally determined on thin films using the 3ω technique at different partial pressures in perfluorohexane, nitrogen, air, and vacuum ambients at 300 K. In contrast to theoretical prediction, the thermal conductivity κ = 0.326 ± 0.002 W/m K was approximately independent of ambient gas species and pressure from atmospheric pressure to vacuum. This work introduces a useful approach for probing MOF thermal conductivity under gas adsorption.

We have prepared nanocrystals of MoS2 across a range of length scales by heating single crystals of the molecular precursor (NH4)(2) Mo3S13 center dot H2O. Rod-shaped crystals of the polysulfide precursor retain their original morphology after heating at temperatures up to 1000 degrees 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)(2) Mo3S13 center dot 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 X 10(14) cm(-3) and mobility of 7 cm(2)/(Vs). The nanocrystals of MoS2 were grown at temperatures ranging from 450 to 1000 degrees 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.

High-surface-area molybdenum sulfide (MoSx) and antimony sulfide (SbSx) chalcogels were studied for Xe/Kr gas separation. The intrinsic soft Lewis basic character of the chalcogel framework is a unique property among the large family of porous materials and lends itself to a potential new approach toward the selective separation of Xe over Kr. Among these chalcogels, MoSx shows the highest Xe and Kr uptake, reaching 0.69 mmol g-1 (1.05 mmol cm-3) and 0.28 mmol g-1 (0.42 mmol cm-3) respectively, at 273 K and 1 bar. The corresponding isosteric heat of adsorption at zero coverage (Qst0) is 22.8 and 18.6 kJ mol-1 and both are the highest among the selected chalcogels. The IAST (10:90) Xe/Kr selectivity at 273 K for MoSx is 6.0, whereas for SbSx chalcogels, it varies in the range 2.0-2.8. The higher formal charge of molybdenum, Mo4+, in MoSx versus that of antimony, Sb3+, in SbSx coupled with its larger atomic size could induce higher polarizability in the MoSx framework and therefore higher Xe/Kr selectivity.

Sulfur cathodes in conversion reaction batteries operate by a different mechanism than that of intercalation materials, and they possess larger theoretical capacities. However, sulfur-based electrode materials suffer from parasitic polysulfide shuttling, which contribute to decreased capacity retention and cyclability. We demonstrate that transition metal polysulfide chalcogels achieve high gravimetric capacity as electrode materials for lithium-ion batteries. Transition metal polysulfide 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. In particular, we examined a 4d transition metal polysulfide chalcogel to investigate the role of the inorganic linker in maintaining structural stability in the electrode. In the MoS3.4 case study, the Mo polysulfide chalcogels function as electrodes in carbonate– as well as ether–based electrolytes and achieve an initial gravimetric capacity of 600 mAh g−1. We employ X-ray absorption 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 anionredox-driven processes. We find the redox state of Mo remains unchanged across the electrochemical cycling even to 1 V and correspondingly, the redox is anion–driven. Chalcogels offer a new class of electrode materials for achieving high-capacity Li-ion

Sulfur cathodes in conversion reaction batteries operate by a different mechanism than that of intercalation materials, and they possess larger theoretical capacities. However, sulfur-based electrode materials suffer from parasitic polysulfide shuttling, which contribute to decreased capacity retention and cyclability. We demonstrate that porous transition metal polysulfide chalcogels achieve high gravimetric capacity as electrode materials for lithium-ion batteries. Transition metal polysulfide 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. In particular, we examined 3d and 4d transition metal polysulfide chalcogels (M’M”Sx in which M is a transition metal) and their role in maintaining structural stability in the electrode. In the MoS3.4 case study, the Mo polysulfide chalcogels function as electrodes in carbonate– as well as ether–based electrolytes and achieve an initial gravimetric capacity of 600 mAh/g. We employ X-ray absorption 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 even to 1 V and correspondingly, the redox is anion–driven. Porous chalcogels offer a new class of electrode materials for achieving high-capacity Li-ion batteries.

Over the last 3-4 decades, solid-state chemistry has emerged as the forefront of materials design and development. The field has revolutionized into a multidisciplinary subject and matured with a scope of new synthetic strategies, new challenges, and opportunities. Understanding the structure is very crucial in the design of appropriate materials for desired applications. Professor Mercouri G. Kanatzidis has encountered both challenges and opportunities during the course of the discovery of many novel materials. Throughout his scientific career, Mercouri and his group discovered several inorganic compounds and pioneered structure-property relationships. We, a few Ph.D. and postdoctoral students, celebrate his 60th birthday by providing a Viewpoint summarizing his contributions to inorganic solid-state chemistry. The topics discussed here are of significant interest to various scientific communities ranging from condensed matter to green energy production.

A layered metal sulfide K2xSn4−xS8−x(x= 0.65–1, KTS-3) is reported for rapid and selective removal of heavy metal ions (Cd2+, Hg2+, Pb2+, Ag+and As3+) from water.

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 rem...

Chalcogels are a new class of aerogel materials with diverse properties relevant to catalysis, ion-exchange, and gas adsorption. We report the synthesis of high-surface-area antimony sulfide chalcogels through the sol-gel process followed by supercritical drying. Four different synthetic routes were employed: (1) hydrolysis of sodium thioantimonite (Na3SbS3); (2) ligand metathesis between SW3+ metal linker and SbS33- anion; (3) reaction of Sb2S3 with Na2S center dot 9H(2)O; and (4) reaction of Sb2S3 with KOH. All these reactions enable the formation of antimony sulfide gels. The aerogels derived after supercritical drying exhibit high porosity with Brunauer-Emmett-Teller (BET) surface areas up to 300 m(2) g(-1). The oxidation state of antimony in these chalcogels has been assigned by X-ray photoelectron spectroscopy (XPS) to be +3. Pair distribution function analysis suggests that the local environment around the Sb atoms is very similar to that of crystalline Sb2S3. All the antimony sulfide chalcogels possess the band gap of similar to 4.75 eV, and they are thermally stable even up to 600 degrees C.

Although great progress in the synthesis of porous networks of metal and metal oxide nanoparticles with highly accessible pore surface and ordered mesoscale pores has been achieved, synthesis of assembled 3D mesostructures of metal-chalcogenide nanocrystals is still challenging. In this work we demonstrate that ordered mesoporous networks, which comprise well-defined interconnected metal sulfide nanocrystals, can be prepared through a polymer-templated oxidative polymerization process. The resulting self-assembled mesostructures that were obtained after solvent extraction of the polymer template impart the unique combination of light-emitting metal chalcogenide nanocrystals, three-dimensional open-pore structure, high surface area, and uniform pores. We show that the pore surface of these materials is active and accessible to incoming molecules, exhibiting high photocatalytic activity and stability, for instance, in oxidation of 1-phenylethanol into acetophenone. We demonstrate through appropriate selection of the synthetic components that this method is general to prepare ordered mesoporous materials from metal chalcogenide nanocrystals with various sizes and compositions.

Tin sulfide (Sn2S3) chalcogels are one of the most effective nonoxide aerogels evaluated to date for iodine gas capture. This is attributed to the fact that the Sn within the gel network has a strong affinity for chemisorption of iodine to form SnI4. This study demonstrates an approach for consolidating the raw and iodine-sorbed Sn2S3 chalcogels into a chalcogenide glass using GeS2 as a glass-forming additive. Adding GeS2 to iodine-sorbed or iodine-free Sn2S3 chalcogels provides better glass formation than Sn–S or Sn–S–I alone, and the quantity of iodine measured in the bulk glass of the consolidated iodine-sorbed Sn2S3 chalcogel was at ∼45 mass%. Additional experiments were conducted using microwave sintering and hot isostatic pressing with iodine-sorbed Sn2S3 xerogels to evaluate alternative consolidation techniques.

We report the synthesis of ion-exchangeable molybdenum sulfide chalcogel through an oxidative coupling process, using (NH4)2MoS4 and iodine. After supercritical drying, the MoS(x) amorphous aerogel shows a large surface area up to 370 m(2)/g with a broad range of pore sizes. X-ray photoelectron spectroscopic and pair distribution function analyses reveal that Mo(6+) species undergo reduction during network assembly to produce Mo(4+)-containing species where the chalcogel network consists of [Mo3S13] building blocks comprising triangular Mo metal clusters and S2(2-) units. The optical band gap of the brown-black chalcogel is ∼1.36 eV. The ammonium sites present in the molybdenum sulfide chalcogel network are ion-exchangeable with K(+) and Cs(+) ions. The molybdenum sulfide aerogel exhibits high adsorption selectivities for CO2 and C2H6 over H2 and CH4. The aerogel also possesses high affinity for iodine and mercury.

The fission of uranium produces radionuclides, 137Cs and 90Sr, which are major constituents of spent nuclear fuel. The half-life of 137Cs and 90Sr is nearly 30 years and thus that makes them harmful to human life and the environment. The selective removal of these radionuclides in the presence of high salt concentrations from industrial nuclear waste is necessary for safe storage. Here we report the synthesis and crystal structure of K2x Sn4-x S8-x (x = 0.65-1, KTS-3) a material which exhibits excellent Cs+, Sr2+ and UO22+ ion exchange properties in varying conditions. The compound adopts a layered structure which consists of exchangeable potassium ions sandwiched between infinite layers of octahedral and tetrahedral tin centers. K2x Sn4-x S8-x (x = 0.65-1, KTS-3) crystallizes in the monoclinic space group P21/c with cell parameters a = 13.092(3) Å, b = 16.882(2) Å, c = 7.375(1) Å and β = 98.10(1)°. Refinement of the single crystal diffraction data revealed the presence of Sn vacancies in the tetrahedra that are long range ordered. The interlayer potassium ions of KTS-3 can be exchanged for Cs+, Sr2+ and UO22+. KTS-3 exhibits rapid and efficient ion exchange behavior in a broad pH range. The distribution coefficients (Kd) for KTS-3 are high for Cs+ (5.5 × 104), Sr2+ (3.9 × 105) and UO22+ (2.7 × 104) at neutral pH (7.4, 6.9, 5.7 ppm Cs+, Sr2+ and UO22+, respectively; V/m ∼ 1000 mL g-1). KTS-3 exhibits impressive Cs+, Sr2+ and UO22+ ion exchange properties in high salt concentration and over a broad pH range, which coupled with the low cost, environmentally friendly nature and facile synthesis underscores its potential in treating nuclear waste.

Iodine (I-129 and I-131) is one of the radionuclides released in nuclear fuel reprocessing and poses a risk to public safety due to its involvement in human metabolic processes. In order to prevent the release of hazardous radioactive iodine into the environment, its effective capture and sequestration is pivotal. In the context of finding a suitable matrix for capturing radioactive iodine, several sulfidic chalcogels were explored as iodine sorbents including NiMoS4, CoMoS4, Sb4Sn3S12, Zn2Sn2S6, and K0.16CoSx (x = 4-5). All of the chalcogels showed high uptake, reaching up to 225 mass % (2.25 g/g) of the final mass owing to strong chemical and physical iodinesulfide interactions. Analysis of the iodine-loaded specimens revealed that the iodine chemically reacted with Sb4Sn3S12, Zn2Sn2S6, and K0.16CoSx to form the metal complexes SbI3, SnI4, and, KI, respectively. The NiMoS4 and CoMoS4 chalcogels did not appear to undergo a chemical reaction with iodine since iodide complexes were not observed with these samples. Once heated, the iodine-loaded chalcogels released iodine in the temperature range of 75 to 220 degrees C, depending on the nature of iodine speciation. In the case of Sb4Sn3S12 and Zn2Sn2S6, iodine release was observed around 150 degrees C mainly in the form of SnI4 and SbI3, respectively. The NiMoS4, CoMoS4, and K0.16CoSx released elemental iodine at similar to 75 degrees C, which is consistent with physisorption. Preliminary investigations on consolidation of iodine-loaded Zn2Sn2S6 chalcogel with Sb2S3 as a glass forming additive produced glassy material whose iodine content was around 25 mass %.

Three of the fundamental catalytic limitations that have plagued the electrochemical production of hydrogen for decades still remain: low efficiency, short lifetime of catalysts and a lack of low-cost materials. Here, we address these three challenges by establishing and exploring an intimate functional link between the reactivity and stability of crystalline (CoS 2 and MoS 2 ) and amorphous (CoS x and MoS x ) hydrogen evolution catalysts. We propose that Co 2+ and Mo 4+ centres promote the initial discharge of water (alkaline solutions) or hydronium ions (acid solutions). We establish that although CoS x materials are more active than MoS x they are also less stable, suggesting that the active sites are defects formed after dissolution of Co and Mo cations. By combining the higher activity of CoS x building blocks with the higher stability of MoS x units into a compact and robust CoMoS x chalcogel structure, we are able to design a low-cost alternative to noble metal catalysts for efficient electrocatalytic production of hydrogen in both alkaline and acidic environments.

A 3D mesoporous network of 6–7 nm BiFeO3 nanoparticles has been successfully prepared by a surfactant-assisted aggregating assembly process. These porous assemblies exhibit large internal surface area, uniform pore size, and impart high catalytic activity for the reduction of p-nitrophenol.

We report the sonochemical synthesis of a hybrid nanoarchitecture composed of ZnO vertically aligned arrays (NRAs) and intercalated (nanofiller) few atomic layers of graphene which exhibits semi-metallic behavior, as a potential hybrid nanomaterial with optoelectronic synergy between its components.