Hydrolysis mechanism of the cyclohexaborate anion: Unraveling the intricacies.

B 6 O 7 OH 6 2 - is a highly polymerized borate anion of three six-membered rings. Limited research on the B 6 O 7 OH 6 2 - hydrolysis mechanism under neutral solution conditions exists. Calculations based on density functional theory show that B 6 O 7 OH 6 2 - undergoes five steps of hydrolysis to form H3BO3 and B OH 4 - . At the same time, there are a small number of borate ions with different degrees of polymerization during the hydrolysis process, such as triborate, tetraborate, and pentaborate anions. The structure of the borate anion and the coordination environment of the bridging oxygen atoms control the hydrolysis process. Finally, this work explains that in existing experimental studies, the reason for the low B 6 O 7 OH 6 2 - content in solution environments with low total boron concentrations is that it depolymerizes into other types of borate ions and clarifies the borate species. The conversion relationship provides a basis for identifying the possibility of various borate ions existing in the solution. This work also provides a certain degree of theoretical support for the cause of the "dilution to salt" phenomenon.

Deciphering the structure and potassium-ion transport mechanism of potassium borate glass.

Potassium borate glass has great potential as an ion transport material. The ion transport rate is closely related to the microstructure of the glass. However, the disorder and variations in boron and oxygen atom types in the glass structure pose challenges in the analysis of this complex glass structure. In this work, the structure of potassium borate glass was unveiled through the neutron diffraction method and ab initio molecular dynamics (AIMD) simulations. The B-O, K-O, and O-O atomic interactions, bond lengths, coordination numbers, cavity distribution, ring structure distributions and other detailed information in the microstructure of potassium borate glass were obtained. By comparing the structure and properties of potassium borate glass with those of crystals of similar components, it is found that the bond lengths of 3B-BO (BO, bridging oxygen), 4B-BO and 3B-NBO (NBO, non-bridging oxygen) are longer than those of corresponding crystals, so the structure of the boron-oxygen network is looser and the density is smaller than that of similar crystals. Moreover, we found a rule that in both borate glass and crystal, the increase of NBO shortened the length of the B-O bond, and the increase of 4B increased the length of the B-O bond. The key structures affecting the transport rate of K+ were NBO, chain structure units and cavities. This work will provide reference data for designing and developing electrically conductive amorphous materials with faster potassium-ion transport rates.