Ti 2 InB 2 , a typical member of MAB phases (a family of layered transition metal borides), has gained wide attention due to its excellent properties. However, in this work, Ti 2 InB 2 is found to share a similar A-site metal whisker growth phenomenon with MAX phases (a family of layered carbides/nitrides), which casts doubt on its reliability, and therefore would hinder its applications in advanced technologies. Specifically, the weaker bond between Ti and In atoms in Ti 2 InB 2 leads to the exfoliation of In atomic layers under mechanical damage. It is proposed that the In atoms released by the mechanochemically decomposed Ti 2 InB 2 have high chemical potentials and are inclined to crystallize, which is responsible for the In whisker growth. Furthermore, it is observed that the decomposition degree of Ti 2 InB 2 affects the whisker growth propensity and morphology. Understanding the In whisker growth mechanism is meaningful to ensure the reliability as Ti 2 InB 2 is finding technological applications.
Jing Jiang,Tanyang Xiao,Chao Pang,Changzheng Li,Aike Liu,Lunhong Ai
Periodate (PI) is emerged as a chemically stable, ecofriendly and safe solid-oxidant to execute advanced oxidation process (AOP) for water decontamination. Nevertheless, the robust catalytic system to efficiently trigger PI activation still remains scarce. The nanolaminated MAB phase Mn 2 AlB 2 consisting of the MnB bilayer interspersed with Al monolayers has been explored for the first time as a new Mn-based catalyst to activate PI for tetracycline (TC) elimination from water. The Mn 2 AlB 2 catalyst exhibits outstanding catalytic performance, achieving a considerable kinetic rate constant (k) of 0.1732 min −1 within 30 min, which is 5.99 times that of PI alone and even superior to counterparts of Al 3+ /PI, Mn 2+ /PI, H 3 BO 3 /PI, Mn 3 O 4 /PI and α-MnO 2 /PI systems. The free radicals of IO 3 and O 2 − combined with nonradical pathway ( 1 O 2 and electron transfer) are responsible for the TC elimination, as evidenced by quenching experiments, electron paramagnetic resonance (EPR) spectroscopy and in situ electrochemical tests. Besides, the TC degradation intermediates are determined and their related toxicities are assessed. This work unveils the PI activation on a new catalytic platform of nanolaminated MAB phase Mn 2 AlB 2 and provides new avenues for the rational design of advanced catalysts for PI-based AOPs.
3D anisotropic functional properties (such as magnetic, electrical, thermal, and optical properties, etc.) in a single material are not only beneficial to the multipurpose of a material, but also helpful to enrich the regulatory dimensionality of functional materials. Herein, a colossal 3D electrical anisotropy of layered MAB-phase MoAlB single crystal is introduced and dissected. Using high-temperature metal-solution method, high-quality MoAlB single crystals are obtained and a surprisingly strong out-of-plane ( σ a / σ b = 1.43 × 10 5 , at 2 K) and in-plane ( σ a / σ c = 12.12, at 2 K) electrical anisotropies are first observed. After a series of experimental and theoretical investigations, it is demonstrated that the 3D anisotropic crystal structure and chemical bond of MoAlB result in its 3D anisotropic phonon vibration and electronic structure, influence the corresponding electron-electron as well as electron-phonon interactions, and finally give rise to its colossal 3D anisotropy of electrical conductivity. This work experimentally and theoretically proves MoAlB single crystal possessing the 3D anisotropies of crystal structure, chemical bond, phonon vibration, electronic structure, and electrical transport, but also provides a promising platform for the future design of functionalized electronic devices as well as synthesis of new and large-sized in-plane anisotropic 2D material (MoBene).
危险品化学品经营许可证（带存储）