Construction of a unique 2-D layered vanadoborate with water-assisted proton conductivity

In the present work, a new two-dimensional layered vanadoborate Na4[V12B18O54(OH)6(H2O)]•(H2en)4•2(OH)•3H2O (1, en = ethylenediamine), based on a [V12B18O54(OH)6(H2O)]10- cluster unit, was hydrothermally obtained and characterized. In the structure, the clusters...

Transition-Metal-Modified Vanadoborate Clusters as Stable and Efficient Photocatalysts for CO2 Reduction

Photocatalytic carbon dioxide reduction (CO₂RR) is considered to be a promising sustainable and clean approach to solve environmental issues. Polyoxometalates (POMs), with advantages in fast, reversible, and stepwise multiple-electron transfer without changing their structures, have been promising catalysts in various redox reactions. However, their performance is often restricted by poor thermal or chemical stability. In this work, two transition-metal-modified vanadoborate clusters, [Co(en)₂]₆[V₁₂B₁₈O₅₄(OH)₆]·17H₂O (V₁₂B₁₈-Co) and [Ni(en)₂]₆[V₁₂B₁₈O₅₄(OH)₆]·17H₂O (V₁₂B₁₈-Ni), are reported for photocatalytic CO₂ reduction. V₁₂B₁₈-Co and V₁₂B₁₈-Ni can preserve their structures to 200 and 250 °C, respectively, and remain stable in polar organic solvents and a wide range of pH solutions. Under visible-light irradiation, CO₂ can be converted into syngas and HCOO^- with V₁₂B₁₈-Co or V₁₂B₁₈-Ni as catalysts. The total amount of gaseous products and liquid products for V₁₂B₁₈-Co is up to 9.5 and 0.168 mmol g^-1 h^-1. Comparing with V₁₂B₁₈-Co, the yield of CO for V₁₂B₁₈-Ni declines by 1.8-fold, while that of HCOO^- increases by 35%. The AQY of V₁₂B₁₈-Co and V₁₂B₁₈-Ni is 1.1% and 0.93%, respectively. These values are higher than most of the reported POM materials under similar conditions. The density functional theory (DFT) calculations illuminate the active site of CO₂RR and the reduction mechanism. This work provides new insights into the design of stable, high-performance, and low-cost photocatalysts for CO₂ reduction.

Study on the source of magnetic properties of three novel boratopolyoxovanadates via two-dimensional infrared correlation spectroscopy

Three novel polyoxovanadoborates namely [V₁₂B₁₈O₄₆(OH)₁₄(H₂O)_0.75]·20.5H₂O 1, Na₂[V₁₂B₁₈O₄₈(OH)₁₂(H₂O)_0.5]·26.5H₂O 2 and Cd_0.5{[Na(H₂O)₂]2[Na(H₂O)]₂[Na(H₂O)₃]2V₁₂B₁₈O₅₃(OH)₇(H₂O)_0.5}·11H₂O 3 have been hydrothermally synthesized and structurally characterized. The boratopolyoxovanadate cage [V₁₂B₁₈O₆₀] backbones in 1-3 are constructed by the combination of two hexameric oxovanadate units [V₆O₉] and one puckered [B₁₈O₄₂] ring via sharing O atoms. All three compounds were obtained under alkaline conditions, and the cluster anions were all [V₁₂B₁₈O₆₀]. But the cations were different, it is inferred that the protonation of the three compound cluster ions is different, respectively [V₁₂B₁₈O₄₆(OH)₁₄(H₂O)_0.75] in 1, [V₁₂B₁₈O₄₈(OH)₁₂(H₂O)_0.5]^2- in 2 and [V₁₂B₁₈O₅₃(OH)₇(H₂O)_0.5]^7- in 3. The V oxidation states ratio of V^IV to V^V were 2:1 confirmed by valence bond calculation and XPS. We studied the magnetic properties of three compounds by two methods: The variable temperature magnetic susceptibility and the 2D IR COS under magnetic perturbation. From the 2D IR COS under magnetic perturbation map, it is showed that all three: (1) the presence of V^IV. (2) Certain quasi-aromaticity from B₃O₃ six-membered ring. (3) The difference of protonation and the charge of the cluster anions. This work enriches the theory of two-dimensional correlation spectroscopy and also provides a new approach to the study of magnetic materials.

The origin of the electronic transitions of mixed valence polyoxovanadoborates [V12B18O60]: from an experimental to a theoretical understanding

New insights in the electronic properties of mixed-valence polyoxovanadoborate clusters.

A new 3-D open-framework Li-rich vanadoborate and its high ionic conductivity after transforming into glasses

A Li-rich vanadoborate was transformed into its glassy phase at 220 °C, which then exhibits high ionic conductivity.

A 3D cadmium–vanadium bimetallic framework with luminescence properties

Luminescent properties of a novel cadmium–vanadium bimetallic 3D framework possessing a pillared-layer.

Employing a new 12-connected topological open-framework copper borovanadate as an effective heterogeneous catalyst for oxidation of benzyl-alkanes

A new 12-connected topological open-framework copper borovanadate with a unique B/V ratio (20/12) and a -B3O7(OH)-Na(μ-OH)[B(OH)2]-B3O7(OH)- connection mode has been hydrothermally obtained and characterized. It not only features the first 3-D copper(II) borovanadate which possesses the largest ratio of TM(2+) and borovanadate anion, but also displays highly catalytic activities for the oxidation of benzyl-alkanes.

A new 3-D open-framework cadmium borovanadate with plane-shaped channels and high catalytic activity for the oxidation of cyclohexanol

A new 3-D open-framework cadmium borovanadate with 6-connected topology was hydrothermally obtained and structurally characterized. It not only features new cadmium(II) borovanadate which possesses an open-framework structure with unique plane-shaped channels, but also exhibits interesting absorption properties and high catalytic activities for the oxidation of cyclohexanol.

Crystal lattice effect on the quenching of the intracluster magnetic interaction in [V12B18O60H6]10− polyoxometalate

Quenching effect of the intracluster antiferromagnetic coupling by alkaline ions of the crystalline packing.