Novel Isopolyoxotungstate [H₂W₁₁O₃₈]^8– Based Metal Organic Framework: As Lewis Acid Catalyst for Cyanosilylation of Aromatic Aldehydes

A novel polyoxometalate-based metal organic framework (POMOF) constructed from isolated isopolyoxotungstate [H₂W₁₁O₃₈]^8– cluster, {[Cu₂(bpy)­(H₂O)_5.5]₂[H₂W₁₁O₃₈]·3H₂O·0.5CH₃CN} (<b>1</b>, where bpy = 4,4′-bpydine), has been synthesized under solvothermal conditions and charaterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. In <b>1</b>, {W₁₁} clusters are alternately linked by two [Cu(2)­(H₂O)_1.5(O_t)₃(N)]²⁺ cations in an unexpected end-to-end fashion leading to a one-dimensional (1D) chain. Adjacent 1D chains are linked through Cu(1)–bpy–Cu(2) in an opposite direction to form a two-dimensional (2D) wavelike sheet along the <i>ab</i> plane. These 2D sheets are further stacked in a parallel fashion giving rise to the 1D channels with copper­(II) cations aligned in the channels. The resulting POMOF acted as a Lewis acid catalyst through a heterogeneous manner to prompt cyanosilylation with excellent efficiency

Beat over the Old Ground with New Strategy: Engineering As···As Interaction in Arsenite-Based Dawson Cluster β‑[W₁₈O₅₄(AsO₃)₂]^6–

By reaction of [As₂W₁₉O₆₇(H₂O)]^14–, NiCl₂·6H₂O, and phen under hydrothermal conditions, a new organic–inorganic tungstoarsenate hybrid [Ni­(phen)₃]₄[As₂W₁₈O₆₀]­{[Ni­(phen)₂]­[H₂As₂W₁₈O₆₀]}·12H₂O (where phen = 1,10-phenanthroline) (<b>1</b>) was obtained via self-assembly and characterized by elemental analysis, infrared (IR) spectroscopy, solid UV–vis absorption spectrum, and single-crystal X-ray diffraction (XRD). An unprecedented 18-tungstoarsenate Dawson cluster, β-[W₁₈O₅₄(AsO₃)₂]^6–, encapsulating two pyramidal arsenite AsO₃^3– anions as templates and exhibiting interesting intramolecular As···As interaction is first achieved. <b>1</b> displays a one-dimensional (1D) chain architecture constructed by alternating β-[W₁₈O₅₄(AsO₃)₂]^6– and nickel­(II) complexes [Ni­(phen)₂)]²⁺. The resulting hybrid can act as a photocatalyst to prompt the degradation of Rhodamine B (RhB) with excellent efficiency

Novel Isopolyoxotungstate [H₂W₁₁O₃₈]^8– Based Metal Organic Framework: As Lewis Acid Catalyst for Cyanosilylation of Aromatic Aldehydes

A novel polyoxometalate-based metal organic framework (POMOF) constructed from isolated isopolyoxotungstate [H₂W₁₁O₃₈]^8– cluster, {[Cu₂(bpy)­(H₂O)_5.5]₂[H₂W₁₁O₃₈]·3H₂O·0.5CH₃CN} (<b>1</b>, where bpy = 4,4′-bpydine), has been synthesized under solvothermal conditions and charaterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. In <b>1</b>, {W₁₁} clusters are alternately linked by two [Cu(2)­(H₂O)_1.5(O_t)₃(N)]²⁺ cations in an unexpected end-to-end fashion leading to a one-dimensional (1D) chain. Adjacent 1D chains are linked through Cu(1)–bpy–Cu(2) in an opposite direction to form a two-dimensional (2D) wavelike sheet along the <i>ab</i> plane. These 2D sheets are further stacked in a parallel fashion giving rise to the 1D channels with copper­(II) cations aligned in the channels. The resulting POMOF acted as a Lewis acid catalyst through a heterogeneous manner to prompt cyanosilylation with excellent efficiency

High-Performance Hard Carbon Anode: Tunable Local Structures and Sodium Storage Mechanism

Hard carbon (HC) is one of the most promising anode materials for sodium-ion batteries (SIBs) due to its suitable potential and high reversible capacity. At the same time, the correlation between carbon local structure and sodium-ion storage behavior is not clearly understood. In this paper, the two series of HC materials with perfect spherical morphology and tailored microstructures were designed and successfully produced using resorcinol formaldehyde (RF) resin as precursor. Via hydrothermal self-assembly and controlled pyrolysis, RF is a flexible precursor for high-purity carbon with a wide range of local-structure variation. Using these processes, one series of five representative RF-based HC nanospheres with varying degrees of graphitization were obtained from an RF precursor at different carbonization temperatures. The other series of HC materials with various microscopic carbon layer lengths and shapes was achieved by carbonizing five RF precursors with different cross-linking degrees at a single carbonization condition (1300 °C and 2 h). On the basis of the microstructures, unique electrochemical characteristics, and atomic pair distribution function (PDF) analyses, we proposed a new model of “three-phase” structural for HC materials and found triregion Na-ion storage behavior: chemi-/physisorption, intercalation between carbon layers, and pore-filling, derived from the HC phases, respectively. These results enable new understanding and insight into the sodium storage mechanism in HC materials and improve the potential for carbon-based SIB anodes

Porous NaTi₂(PO₄)₃/C Hierarchical Nanofibers for Ultrafast Electrochemical Energy Storage

NaTi₂(PO₄)₃ (NTP) with a sodium superionic conductor three-dimensional (3D) framework is a promising anode material for sodium-ion batteries (SIBs) because of its suitable potential and stable structure. Although its 3D structure enables high Na-ion diffusivity, low electronic conductivity severely limits NTP’s practical application in SIBs. Herein, we report porous NTP/C nanofibers (NTP/C-NFs) obtained via an electrospinning method. The NTP/C-NFs exhibit a high reversible capacity (120 mA h g^–1 at 0.2 C) and a long cycling stability (a capacity retention of ∼93% after 700 cycles at 2 C). Furthermore, sodium-ion full cells and hybrid sodium-ion capacitors have also been successfully assembled, both of which exhibit high-rate capabilities and remarkable cycling stabilities because of the high electronic/ionic conductivity and impressive structural stability of NTP/C-NFs. The results show that the nanoscale-tailored NTP/C-NFs could deliver new insights into the design of high-performing and highly stable anode materials for room-temperature SIBs