Acid-Induced Conversions in Open-Framework Semiconductors: From [Cd4Sn3Se13]6− to [Cd15Sn12Se46]14−, a Remarkable Disassembly/Reassembly Process

Structural Investigation on the Efficient Capture of Cs+ and Sr2+ by a Microporous Cd-Sn-Se Ion Exchanger Constructed from Mono-Lacunary Supertetrahedral Clusters

Visualization of the ion exchange mechanism for 137Cs and 90Sr decontamination bears significance for safe radioactive liquid waste reprocessing and emergency response enhancement to nuclear accident. Here, the remediation of...

Strongly Coupled Cobalt Diselenide Monolayers for Selective Electrocatalytic Oxygen Reduction to H2 O2 under Acidic Conditions

Electrosynthesis of hydrogen peroxide (H₂ O₂ ) in the acidic environment could largely prevent its decomposition to water, but efficient catalysts that constitute entirely earth-abundant elements are lacking. Here we report the experimental demonstration of narrowing the interlayer gap of metallic cobalt diselenide (CoSe₂ ), which creates high-performance catalyst to selectively drive two-electron oxygen reduction toward H₂ O₂ in an acidic electrolyte. The enhancement of the interlayer coupling between CoSe₂ atomic layers offers a favorable surface electronic structure that weakens the critical *OOH adsorption, promoting the energetics for H₂ O₂ production. Consequently, on the strongly coupled CoSe₂ catalyst, we achieved Faradaic efficiency of 96.7 %, current density of 50.04 milliamperes per square centimeter, and product rate of 30.60 mg cm^-2  h^-1 . Moreover, this catalyst shows no sign of degradation when operating at -63 milliamperes per square centimeter over 100 hours.

Efficient Cs+-Sr2+ Separation over a Microporous Silver Selenidostannate Synthesized in Deep Eutectic Solvent

Efficient Cs⁺-Sr²⁺ separation, highly desirable for radionuclide recovery in medical and industrial applications, was achieved by the ion exchange technique over a novel microporous silver selenidostannate, [NH₃CH₃]_0.5[NH₂(CH₃)₂]_0.25Ag_1.25SnSe₃ (AgSnSe-1). This material was synthesized in deep eutectic solvent (DES), where the alkylammonium cations play significant structure-directing roles in the construction of micropores that allow for selective ion exchange toward Cs⁺ against Sr²⁺. The much greater K_d^Cs (1.06 × 10⁴ mL g^-1) over K_d^Sr (87.7 mL g^-1) contributes to an outstanding separation factor SF_Cs/Sr of ∼121.4 that is top-ranked among inorganic materials. An ion exchange column filled with AgSnSe-1 exhibits a remarkable separation effect for 10 000 bed volumes of continuous flow, with removal rates of ∼99.9% and ∼0 ± 5.5% for Cs⁺ and Sr²⁺, respectively. AgSnSe-1 exhibits excellent β and γ radiation resistances and a chemical stability over a broad pH range of 1-12. The Se leaching level below the safe guideline value for drinking water highlights the environmental-friendly nature of AgSnSe-1. The high Cs⁺ exchange performance is almost unaffected by Na⁺, Mg²⁺, and Ca²⁺ cations. The Cs⁺-laden product AgSnSe-1Cs can be facilely eluted for recycling use, highlighting the great potential of open framework metal selenides in nuclear waste treatment and renewable energy utilization.

Deep eutectic solvothermal synthesis of an open framework copper selenidogermanate with pH-resistant Cs+ ion exchange properties

Reported here is the deep eutectic solvothermal synthesis of an open framework copper selenidogermanate [NH₃CH₃]_0.75Cu_1.25GeSe₃ (CuGeSe-1), which shows a pH-resistant Cs⁺ ion exchange performance (q_m = 225.3 mg g⁻¹).

Synthesis and characterization of a new mid-infrared transparent compound: acentric Ba5In4Te4S7

A new infrared nonlinear optical crystal with mixed anions: S–Te.

Designing the syntheses and photophysical simulations of noncentrosymmetric compounds

The designs of NCS compounds based on the normal development of NCS chromophores are presented and NLO properties are investigated.

Old materials with new tricks: multifunctional open-framework materials

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)

Heavy-Metal-Ion Capture, Ion-Exchange, and Exceptional Acid Stability of the Open-Framework Chalcogenide (NH4)4In12Se20

The hydrothermal synthesis of the purely inorganic open-framework indium selenide (NH(4))(4)In(12)Se(20) (1) is reported. Compound 1 exhibits a unique three-dimensional open-framework structure. The framework of 1 shows an unusual, for a chalcogenide compound, rigidity arising from the unprecedented connection mode of its building blocks. Compound 1 possesses ion exchange capacity for Cs(+), Rb(+), NH(4) (+), but it has selectivity against Na(+) and Li(+). It also showed exceptional stability in relatively concentrated hydrochloric acid. Ion exchange of 1 with hydrochloric water solutions can produce its solid acid analogue H(2)(NH(4))(2)In(12)Se(20). The maximum cation-exchange capacity of 1 was found equal to two equivalents per mol, which is consistent with an exchange mechanism taking place in the 1D-channels formed by the largest cavities. In addition, 1 can do ion-exchange with heavy-metal ions like Hg(2+), Pb(2+), and Ag(+). The capacity of 1 to clean water solutions from heavy-metal ions was preliminarily investigated and found very high. Specifically, 1 can remove 99.9 % of Hg(2+), 99.8 % of Ag(+), and 94.9 % of Pb(2+) from aqueous solutions of each of these ions. Using different synthetic conditions, we isolated compound (NH(4))(2)In(12)Se(19) (2), which also has as good an acid stability as 1, but no ion-exchange properties. Overall, this work provides new hydrothermal synthetic approaches for isolation of all-inorganic open-framework chalcogenides.

Unique Pore Selectivity for Cs+ and Exceptionally High NH4+ Exchange Capacity of the Chalcogenide Material K6Sn[Zn4Sn4S17]

Highly selective ion-exchange properties and -exchange capacities of the open framework chalcogenide material K(6)Sn[Zn(4)Sn(4)S(17)] (1) with Cs(+) and NH(4)(+) are reported. Because the structure of this framework is known in great detail, these studies are a rare example where structure/property relationships can be directly drawn. 1 possesses three types of micropore cavities. The largest pore of 1 presents an exact fit for Cs(+) and exhibits high selectivity for this ion, as demonstrated by competitive ion-exchange experiments. The next largest pore has a greater capacity (up to four cations) and is well suited for NH(4)(+) ions. This leads to a high ammonium-exchange capacity for 1 of 3.06 mequiv/gr, which is close to the NH(4)(+)-exchange capacities of natural zeolites. The single-crystal structures of ammonium-exchanged products at various stages reveal an unusual mechanism for the exchange process of 1 which involves diffusion of ammonium cations from the large cavity to the small ones of the framework. Thermal analysis of one of these ammonium-exchanged products, in combination with mass spectroscopy, showed the decomposition of NH(4)(+) cations to NH(3) and H(2)S with the parallel transformation of the exchanged product to a mixture of crystalline phases. Since K(6)Sn[Zn(4)Sn(4)S(17)] can be grown in suitably large crystals (much larger than most zeolites), it defines an excellent model system in which ion-exchange processes and products can be characterized and studied in detail in various reaction stages.