Hierarchical γ-BaB₂O₄ hollow microspheres: surfactant-assisted hydrothermal formation, phase conversion, optical properties and application as adsorbents

Abstract

Three-dimensional (3D) hierarchical metal borates nanoarchitectures have attracted extensive concern for their wide employment owing to the versatile compositions and unique properties, whose rational design and facile synthesis with high uniformity and complex interiors have been long remained a great challenge. In this contribution, hierarchical γ-BaB 2 O 4 hollow microspheres assembled by one-dimensional (1D) nanorods were successfully synthesized by a facile ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal method (180 ºC, 12 h), using Ba(OH) 2 ·8H 2 O and H 3 BO 3 as the raw materials. The effects of process parameters were investigated in detail, and based on which a feasible formation mechanism was proposed. The hierarchical γ-BaB 2 O 4 hollow microspheres exhibited a specific surface area of 46.25 m 2 g -1 . The subsequent mild phase conversion (700 ºC, 3.0 h) led to the β-BaB 2 O 4 hollow microspheres with well-preserved spherical morphology and high crystallinity, indicating the hierarchical γ-BaB 2 O 4 and β-BaB 2 O 4 hollow microspheres of excellent thermostability. Both the hierarchical γ-BaB 2 O 4 and β-BaB 2 O 4 hollow microspheres exhibited a transparent characteristic from the ultraviolet to the visible region. Moreover, when employed as adsorbents, the hierarchical γ-BaB 2 O 4 hollow microspheres presented satisfactory adsorption properties for the removal of Pb 2+ from mimic waste water, suggesting that the great potential applications of the 3D * Corresponding authors. Tel.2 hierarchical porous or hollow nanoarchitectures of metal borates in future.

Exploration of the oxygen reduction reaction activity of four transition metal borates: synthesis, structure and characterization

“…Borates are rich in structures and widely used in nonlinear optics, lasers, adsorption, flame retardants, catalysis and other fields. [1][2][3][4][5][6][7][8][9][10][11] From the structural chemistry point of view, the coordination of boron atoms with oxygen in BO 3 is triangular and in BO 4 is tetrahedral, which further give rise to borates with a variety of structural types. BO 3 These polyanionic clusters extend borate chains, sheets and frameworks through dehydration/condensation.…”

“…[20][21][22] Therein, transition metal borates have attracted extensive research interest due to their rich structural chemistry and various applications in catalysis. 1,9,23,24 The d 10 electronic configuration of transition metal ions and their susceptibility to large polarization endow their compounds with good physicochemical properties. [25][26][27][28][29][30] Furthermore, because of the advantages of metal complexes with diverse charges, unique geometric configurations and diverse sites of hydrogen bonds (H-Bs), which can affect the formation of boron oxygen clusters, they provide a broad exploration space for complexes in borates constructed from metal ions and organic ligands.…”

“…Borates are rich in structures and widely used in nonlinear optics, lasers, adsorption, flame retardants, catalysis and other fields. 1–11 From the structural chemistry point of view, the coordination of boron atoms with oxygen in BO 3 is triangular and in BO 4 is tetrahedral, which further give rise to borates with a variety of structural types. BO 3 and BO 4 are interconnected by sharing vertices or edges to form different polyanionic clusters, such as [B 4 O 5 (OH) 4 ] 2− , [B 5 O 6 (OH) 4 ] − , [B 6 O 7 (OH) 6 ] 2− , [B 7 O 9 (OH) 5 ] 2− , [B 8 O 10 (OH) 6 ] 2− , [B 9 O 12 (OH) 6 ] 3− , etc .…”

Novel application of imidazole-based ligand-templated borates in a zinc–air battery

“…In recent years, with the widespread application of the borate family in nonlinear optics, fluorescence and catalysis, the methods for preparing these materials have also developed rapidly. 1 Oxoboron hybrid clusters with metal as the connection site have received extensive attention for synthesis. Borate group species such as nickel borate, zinc borate and cobalt borate have been extensively studied.…”