Synthesis of ZnIn2S4@Co3S4 particles derived from ZIF-67 for photocatalytic hydrogen production.

In this work, ZIF-67 derivative Co3S4 with diamond dodecahedron structure was firstly synthesized via a series of reactions, and ZnIn2S4@Co3S4 heterostructures with adjustable band gaps were successfully obtained through a simple hydrothermal method. Consequently, ZnIn2S4@Co3S4 heterostructures have significantly enhanced visible light absorption and improved photocatalytic efficiency, among which the ZC-5 composite exhibits the highest photocatalytic hydrogen production rate up to 4261 µmol g-1 h-1 under simulated sunlight, to be approximately 4.8 times higher than that of pure ZnIn2S4. The enhanced photocatalytic activity can be attributed to faster electron transfer and more efficient electron-hole pairs separation derived from the heterostructures which form at the interface between Co3S4 and ZnIn2S4. Thus, this study provides a good strategy for photocatalytic hydrogen production without precious metals using heterostructures.

Visible-Near-Infrared-Light-Driven Oxygen Evolution Reaction with Noble-Metal-Free WO2-WO3 Hybrid Nanorods.

Understanding and manipulating the one half-reaction of photoinduced hole-oxidation to oxygen are of fundamental importance to design and develop an efficient water-splitting process. To date, extensive studies on oxygen evolution from water splitting have focused on visible-light harvesting. However, capturing low-energy photons for oxygen evolution, such as near-infrared (NIR) light, is challenging and not well-understood. This report presents new insights into photocatalytic water oxidation using visible and NIR light. WO2-WO3 hybrid nanorods were in situ fabricated using a wet-chemistry route. The presence of metallic WO2 strengthens light absorption and promotes the charge-carrier separation of WO3. The efficiency of the oxygen evolution reaction over noble-metal-free WO2-WO3 hybrids was found to be significantly promoted. More importantly, NIR light (≥700 nm) can be effectively trapped to cause the photocatalytic water oxidation reaction. The oxygen evolution rates are even up to around 220 (λ = 700 nm) and 200 (λ = 800 nm) mmol g-1 h-1. These results demonstrate that the WO2-WO3 material is highly active for water oxidation with low-energy photons and opens new opportunities for multichannel solar energy conversion.

An Adsorbate Discriminatory Gate Effect in a Flexible Porous Coordination Polymer for Selective Adsorption of CO2 over C2H2.

The adsorptive separation of C2H2 and CO2 via porous materials is nontrivial due to the close similarities of their boiling points and kinetic diameters. In this work, we describe a new flexible porous coordination polymer (PCP) [Mn(bdc)(dpe)] (H2bdc = 1,4-benzenedicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene) having zero-dimensional pores, which shows an adsorbate discriminatory gate effect. The compound shows gate opening type abrupt adsorption for C2H2 but not for CO2, leading to an appreciable selective adsorption of CO2 over C2H2 at near ambient temperature (273 K). The origin of this unique selectivity, as unveiled by in situ adsorption-X-ray diffraction experiments and density functional theory calculations, is due to vastly different orientations between the phenylene ring of bdc and each gas in the nanopores. The structural change by photochemical transformation of this PCP via [2 + 2] photodimerization leads to the removal of inverse CO2/C2H2 selectivity, verifying the mechanism of the guest discriminatory gate effect.

Interfacial Synthesis of Electrically Conducting Palladium Bis(dithiolene) Complex Nanosheet.

The synthesis of palladium bis(dithiolene) complex nanosheets (PdDt) possessing a kagome-type lattice structure was performed via interfacial reaction between metal salt in aqueous phase and dithiolato ligand in organic phase. The PdDt nanosheets were characterised by AFM, STM, TEM revealing flat and sheet-like morphology; IR, UV spectroscopy show the corresponding coordination connectivity between metal and ligand, followed by powder X-ray diffraction and SAED, which determined nanosheets to be structurally similar to previously reported nickel bis(dithiolene) complex nanosheets NiDt.

A crystalline porous coordination polymer decorated with nitroxyl radicals catalyzes aerobic oxidation of alcohols.

A porous coordination polymer (PCP) has been synthesized employing an organic ligand in which a stable free radical, isoindoline nitroxide, is incorporated. The crystalline PCP possesses one-dimensional channels decorated with the nitroxyl catalytic sites. When O2 gas or air was used as the oxidant, this PCP was verified to be an efficient, recyclable, and widely applicable catalyst for selective oxidation of various alcohols to the corresponding aldehydes or ketones.

A family of rare earth porous coordination polymers with different flexibility for CO2/C2H4 and CO2/C2H6 separation.

A family of new porous coordination polymers (PCPs) were prepared by the reaction of an acylamide modified ligand (H3L) and RE(NO)3·xH2O (RE = Y, La, Ce, Nd, Eu, Tb, Dy, Ho, and Tm). PXRD and single-crystal X-ray analyses of them revealed that, besides the La PCP, all other rare earth members gave isomorphous structures. The two types of structural toplogies obtained, although similar, differ in their alignment of acylamide functional groups and structural flexibility. Adsorption experiments and in situ DRIFT spectra showed that rigid frameworks have the typical microporous behavior and poor selective capture of CO2 over C2H4 and C2H6; however, the unique La-PCP with structural flexibility and close-packed acylamide groups has a high selective capture of CO2 with respect to C2H6 or C2H4 at 273 K, especially at the ambient pressure area (0.1-1 bar).

Modular design of domain assembly in porous coordination polymer crystals via reactivity-directed crystallization process.

The mesoscale design of domain assembly is crucial for controlling the bulk properties of solids. Herein, we propose a modular design of domain assembly in porous coordination polymer crystals via exquisite control of the kinetics of the crystal formation process. Employing precursors of comparable chemical reactivity affords the preparation of homogeneous solid-solution type crystals. Employing precursors of distinct chemical reactivity affords the preparation of heterogeneous phase separated crystals. We have utilized this reactivity-directed crystallization process for the facile synthesis of mesoscale architecture which are either solid-solution or phase-separated type crystals. This approach can be also adapted to ternary phase-separated type crystals from one-pot reaction. Phase-separated type frameworks possess unique gas adsorption properties that are not observed in single-phasic compounds. The results shed light on the importance of crystal formation kinetics for control of mesoscale domains in order to create porous solids with unique cooperative functionality.

Synthesis and characterization of a 1-D porous barium carboxylate coordination polymer, [Ba(HBTB)] (H3BTB = benzene-1,3,5-trisbenzoic acid).

The synthesis and characterization of [Ba(HBTB)] is reported. This is the first porous framework synthesized with barium using carboxylate ligands. The framework has robust microporous character (Langmuir surface area of 879 m(2) g(-1)) and possesses unsaturated metal sites when fully desolvated.

A solid lithium electrolyte via addition of lithium isopropoxide to a metal-organic framework with open metal sites.

The uptake of LiO(i)Pr in Mg(2)(dobdc) (dobdc(4-) = 1,4-dioxido-2,5-benzenedicarboxylate) followed by soaking in a typical electrolyte solution leads to the new solid lithium electrolyte Mg(2)(dobdc)·0.35LiO(i)Pr·0.25LiBF(4)·EC·DEC (EC = ethylene carbonate; DEC = diethyl carbonate). Two-point ac impedance data show a pressed pellet of this material to have a conductivity of 3.1 × 10(-4) S/cm at 300 K. In addition, the results from variable-temperature measurements reveal an activation energy of just 0.15 eV, while single-particle data suggest that intraparticle transport dominates conduction.

An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions.

Strong CO2 binding in a water-stable, triazolate-bridged metal-organic framework functionalized with ethylenediamine.

Reaction of CuCl(2) x 2 H(2)O with 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene (H(3)BTTri) in DMF at 100 degrees C generates the metal-organic framework H(3)[(Cu(4)Cl)(3)(BTTri)(8)(DMF)(12)] x 7 DMF x 76 H(2)O (1-DMF). The sodalite-type structure of the framework consists of BTTri(3-)-linked [Cu(4)Cl](7+) square clusters in which each Cu(II) center has a terminal DMF ligand directed toward the interior of a large pore. The framework exhibits a high thermal stability of up to 270 degrees C, as well as exceptional chemical stability in air, boiling water, and acidic media. Following exchange of the guest solvent and bound DMF molecules for methanol to give 1-MeOH, complete desolvation of the framework at 180 degrees C generated H(3)[(Cu(4)Cl)(3)(BTTri)(8)] (1) with exposed Cu(II) sites on its surface. Following a previously reported protocol, ethylenediamine molecules were grafted onto these sites to afford 1-en, featuring terminal alkylamine groups. The N(2) adsorption isotherms indicate a reduction in the BET surface area from 1770 to 345 m(2)/g following grafting. The H(2) adsorption data at 77 K for 1 indicate a fully reversible uptake of 1.2 wt % at 1.2 bar, while the CO(2) isotherm at 195 K shows a maximal uptake of 90 wt % at 1 bar. Compared to 1, the alkylamine-functionalized framework 1-en exhibits a higher uptake of CO(2) at 298 K and pressures up to ca. 0.1 bar, as well as a higher CO(2)/N(2) selectivity at all measured pressures. Significantly, 1-en also exhibits an isosteric heat of CO(2) adsorption of 90 kJ/mol, which is much higher than the 21 kJ/mol observed for 1. This chemisorption interaction is the strongest reported to date for a metal-organic framework and points toward the potential utility of alkylamine-appended frameworks for the postcombustion capture of CO(2) from low-pressure flue gas streams.

Hinged nanorods made using a chemical approach to flexible nanostructures.

The fabrication of multifunctional nanomaterials and their subsequent use for novel applications in various branches of nanotechnology has been under intense scrutiny. Particularly in the area of nanomechanics, the design of multicomponent nanostructures with an integrated multifunctionality would enable the construction of building blocks for nanoscale analogues of macroscopic objects. Here, we introduce a new class of flexible nanostructures: metallic nanorods with polyelectrolyte hinges, synthesized using layer-by-layer electrostatic self-assembly of oppositely charged polyelectrolytes on barcode metal nanorods followed by segment-selective chemical etching. Nanorods with hinges that consist of one polyelectrolyte bilayer display considerable flexibility, but with a greater number of bilayers the flexibility of the hinge is significantly reduced. Magnetically induced bending about the polymer hinge is illustrated through the incorporation of nickel segments into the barcodes and the application of an external fluctuating magnetic field.

Charge ordering, commensurability, and metallicity in the phase diagram of the layered NaxCoO2.

The phase diagram of nonhydrated NaxCoO2 has been determined by changing the Na content x using a series of chemical reactions. As x increases from 0.3, the ground state goes from a paramagnetic metal to a charge-ordered insulator (at x=1/2), then to a "Curie-Weiss metal" (around 0.70), and finally to a weak-moment magnetically ordered state (x>0.75). The unusual properties of the state at 1/2 (including particle-hole symmetry at low T and enhanced thermal conductivity) are described. The strong coupling between the Na ions and the holes is emphasized.