Al8(BO3)4(B2O5)F8: A F-Containing Aluminum Borate Featuring Two Types of Isolated B-O Groups

Structural Motif Cosubstitution Strategy for Designing Fluoroaluminoborate with the Sr2Be2B2O7-Type Double-Layered Structure

The cosubstitution strategy often was applied to design borate optical crystal materials. Revealingly, a fluoroaluminoborate Sr₂Al_2.18B_5.82O₁₃F₂ with Sr₂Be₂B₂O₇ (SBBO) double-layered like configuration has been rationally designed and successfully synthesized based on structural motif cosubstitution strategy via the high-temperature solution method. In Sr₂Al_2.18B_5.82O₁₃F₂, a structural motif, the [Al₂B₆O₁₄F₄] unit, with edge-sharing [AlO₄F₂] octahedra was filled in interlamination of double-layer structure. The research indicates that Sr₂Al_2.18B_5.82O₁₃F₂ features a short ultraviolet cutoff edge (<200 nm) and moderate birefringence (∼0.058 @ 1064 nm). As the first reported linker in the interlamination of double-layer structures, the [Al₂B₆O₁₄F₄] unit enlightens the synthesis and discovery of new layered structures in borates.

Li3B8O13X (X = Cl and Br): Two New Noncentrosymmetric Crystals with Large Birefringence Induced by BO3 Units

Enthusiasm for the exploration of nonlinear alkali metal borates remains high. Focusing on the Li-B-O-X (X = Cl and Br) system, two examples of noncentrosymmetric borates, Li₃B₈O₁₃Cl and Li₃B₈O₁₃Br, were obtained using a high-temperature solution method under vacuum conditions. Structurally, the Li₃B₈O₁₃X crystals exhibit two independent alternately arranged three-dimensional B-O network structures formed by the basic building block unit B₈O₁₆. The performance measurements demonstrate their short ultraviolet cutoff edges. The theoretical calculation indicates that the BO₃ units dominate the contribution to their large optical anisotropy with the birefringence, 0.094 and 0.088@1064 nm for Li₃B₈O₁₃Cl and Li₃B₈O₁₃Br, respectively.

Pb2Al2B3O8F3: Structure and Properties of a New Fluoroaluminoborate with Non-traditional Chain-like B3O8 Group

A new fluoroaluminoborate, Pb2Al2B3O8F3, with a non-traditional chain [B3O8]7- was synthesized by high temperature reactions in closed systems for the first time. Different from the traditional [B3O8]7- ring [(3:Δ +...

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.