Efficient proton conductivity of a novel 3D open-framework vanadoborate with [V6B20] architectures

Heptanuclear Cadmium Borovanadate Containing a Sandwich-Type Anionic Partial Structure {B20V12} as a Heterogeneous Photocatalyst for the Reduction of CO2 into CH4

The novel heptanuclear cadmium borovanadate [Cd(en)3]{[Cd(H2O)(en)]6[B20V12O60(OH)2]}·8H2O (en = ethylenediamine) has been prepared under hydrothermal condition. It exhibits a 2D layered architecture that is built up from the [Cd(H2O)(en)]2+ coordination cations and new sandwich-type borovanadate anions [B20V12O60(OH)2]14- constructed by BO3, BO4, BO3(OH), and VO5 units. It features the first heptanuclear cadmium borovanadate containing the single valence of V4+ cations and unique B/V ratio (B/V = 20/12). Its thermal, magnetic, XPS, and optical properties have been systematically studied. The Eg (2.60 eV), EVB (1.69 eV), and ECB (-0.91 eV) were well determined by the UV-vis diffuse reflectance spectrum, UPS curve, and the formula ECB = EVB - Eg, respectively. The photocatalytic experiments revealed that the borovanadate could be selected as an effective and stable heterogeneous catalyst for the reduction of CO2 to CH4 by means of visible light (the amount for CH4 gas could reach 50.57 μmol·g-1·h-1 when the reaction time was 3 h). The recycling experiment and photocatalytic mechanism were also well investigated and established in detail.

Gladstone-Dale compatibility, electronic polarizability and vibrational spectroscopy of minerals and inorganic compounds with V4+O and V4+O2 vanadyl groups

VO and VO2 vanadyl groups with short (typically 1.57-1.68 Å), essentially covalent, V-O bonds are common for V4+-bearing oxysalts with [5]- and [6]-coordinated vanadium. There is a clear negative correlation between vanadyl bond lengths and wavenumbers of the bands of V-O stretching vibrations in infrared spectra (in the range 1000-880 cm-1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone-Dale compatibility coefficients. Gladstone-Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V4+. Unlike compounds of [5]-coordinated Ti4+, for most minerals with V4+=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.

Elimination of grain boundary resistance in vanadoborate electrolyte via the hydrogen-bond interaction of glycerol

An effective method to eliminate grain boundary resistance of crystalline vanadoborate electrolyte was developed. This method involved the addition of glycerol to result in the formation of many hydrogen bonds between crystal grains, facilitating a rapid transfer of protons across grain boundaries. Using this method, the intrinsic conduction of vanadoborate electrolyte was fully reflected in its bulk materials, valuable for advancing our understanding of vanadoborate electrolytes and for promoting the application of these electrolytes.

A highly efficient heterogeneous catalyst for selective oxidation of sulfides derived from an open-framework copper borovanadate containing a unique crown-shaped anion

A novel 3D open-framework copper borovanadate with a unique crown-shaped anion [(V^IVO)₈(V^VO)₄B₃₂O₆₄(OH)₈]^12- and the largest ratio of Cu²⁺/borovanadate anions (6/1) has been successfully synthesized and systematically studied. The compound not only possesses high stability in a wide pH range of 3.2-10.8 (DMF solution), but also exhibits excellent catalytic activities for selective oxidation of sulfides.

Water assisted high proton conductance in a pure-inorganic framework vanadoborate

A pure-inorganic framework vanadoborate is successfully synthesized under hydrothermal conditions and exhibits good proton conductivity.