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Ternary MAB phases (layered transition metal borides) have recently attracted interest due to their exfoliation potential toward MBenes (analogous to MXenes), which are predicted to have excellent Li-ion battery performance. We have achieved single-phase synthesis of two MAB phases with general composition Ni n+1 ZnB n ( n = 1, 2), the crystal structures of which contain zinc layers sandwiched between thin ( n = 1) and thick ( n = 2) Ni–B slabs. Highly stacked MAB sheets were confirmed by X-ray diffraction and high-resolution scanning electron microscopy for both materials. Exposing Ni n+1 ZnB n to diluted hydrochloric acid led to the creation of crystalline microporous structures for n = 1 and non-porous detached sheets for n = 2. Both morphologies transformed the inactive bulk materials into highly active Li-ion battery anodes with capacities of ∼90 mA h g −1 ( n = 1) and ∼70 mA h g −1 ( n = 2) at a 100 mA g −1 lithiation–delithiation rate. The XPS analysis and BET surface area measurements reveal that the increased surface area and the reversible redox reaction of oxidized nickel species are responsible for this drastic increase of the lithiation–delithiation capacity. This proof of conceptmore »opens new avenues for the development of porous MAB, MAB nanosheets, MBenes and their composites for metal-ion battery applications.« less

Whilst MXenes (2D carbides and nitrides) have become highly popular in several research fields including the hydrogen evolution reaction (HER), unfortunately they are not competitive HER electrocatalysts in their bulk form (MAX phases). The related MAB (2D‐like bulk borides) phases and the derived 2D MBenes, however, are less studied but show better HER properties. Herein, two highly HER‐active and abundant MAB phases, Ni_n+1ZnB_n(n = 1, 2), are studied experimentally and computationally. The pressed pellet electrodes from bulk polycrystalline powders of these phases drive a current density of 10 mA cm⁻²at impressive overpotentials ofη₁₀ = −0.171 V (n = 1) andη₁₀= −0.145 V (n = 2) to efficiently produce hydrogen. Density functional theory (DFT) calculations prove that the most active site is the hollow site on the nickel basal plane, showing a free energy value comparable to that of the hollow site of Pt (111). This study paves the way for further development of bulk and nanoscale MAB phases for clean energy applications.