Two-Dimensional Transition Metal Boron Cluster Compounds (MB_<i>n</i>enes) with Strain-Independent Room-Temperature Magnetism

Two-dimensional (2D) metal borides (MBenes) with unique electronic structures and physicochemical properties hold great promise for various applications. Given the abundance of boron clusters, we proposed employing them as structural motifs to design 2D transition metal boron cluster compounds (MBnenes), an extension of MBenes. Herein, we have designed three stable MBnenes (M4(B12)2, M = Mn, Fe, Co) based on B12 clusters and investigated their electronic and magnetic properties using first-principles calculations. Mn4(B12)2 and Co4(B12)2 are semiconductors, while Fe4(B12)2 exhibits metallic behavior. The unique structure in MBnenes allows the coexistence of direct exchange interactions between adjacent metal atoms and indirect exchange interactions mediated by the clusters, endowing them with a Néel temperature (TN) up to 772 K. Moreover, both Mn4(B12)2 and Fe4(B12)2 showcase strain-independent room-temperature magnetism, making them potential candidates for spintronics applications. The MBnenes family provides a fresh avenue for the design of 2D materials featuring unique structures and excellent physicochemical properties

Nickel Vacancies Boost Reconstruction in Nickel Hydroxide Electrocatalyst

Because the reconstruction of catalysts is generally observed during oxidation reactions, understanding the intrinsic structure-related reconstruction ability of electrocatalysts is highly desirable but challenging. Herein, a controllable hydrolysis strategy is developed to obtain nickel hydroxide electrocatalysts with controllable nickel vacancy (V_Ni) concentrations, as confirmed by advanced spectroscopic characterization. Electrochemical measurements show that the reconstruction can be promoted with the increase of V_Ni concentration to generate true active components, thereby boosting activities for both oxygen evolution reaction (OER) and urea oxidation reaction (UOR). Density functional theory calculations confirm that the increased V_Ni concentration yields decreased formation energies of the true active components during reactions. This work provides fundamental understanding of the reconstruction ability of electrocatalysts in anodic oxidation reactions from the view of intrinsic defects

Electron-Doped 1T-MoS₂ via Interface Engineering for Enhanced Electrocatalytic Hydrogen Evolution

Designing advanced electrocatalysts for hydrogen evolution reaction is of far-reaching significance. Active sites and conductivity play vital roles in such a process. Herein, we demonstrate a heteronanostructure for hydrogen evolution reaction, which consists of metallic 1T-MoS₂ nanopatches grown on the surface of flexible single-walled carbon nanotube (1T-MoS₂/SWNT) films. The simulated deformation charge density of the interface shows that 0.924 electron can be transferred from SWNT to 1T-MoS₂, which weakens the absorption energy of H atom on electron-doped 1T-MoS₂, resulting in superior electrocatalytic performance. The electron doping effect via interface engineering renders this heteronanostructure material outstanding hydrogen evolution reaction (HER) activity with initial overpotential as small as approximately 40 mV, a low Tafel slope of 36 mV/dec, 108 mV for 10 mA/cm², and excellent stability. We propose that such interface engineering could be widely used to develop new catalysts for energy conversion application