Highly Active and Abundant MAB Phases Nin+1ZnBn (n = 1, 2) toward Hydrogen Evolution

Abstract

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, Nin+1ZnBn (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−2 at impressive overpotentials of η10 = −0.171 V (n = 1) and η10= −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.