NiB monolayer: A topological metal with high NORR electrocatalytic perfomance

Electrochemical reduction reaction of NO (NORR) offers a promising strategy for effective removal of NO coupled with synthesis of NH3. In this study, the newly reported NiB monolayer with topological metal properties is proved to have excellent catalytic activity and high selectivity toward NO-to-NH3 conversion by using density functional theory (DFT) and the constant potential method (CPM). Calculations reveal that the peculiar building blocks of Ni-B triangles and tetragons can facilitate NO adsorption and activation via an electron donation-back-donation interaction mechanism. The predicted free energy profiles of the four considered NORR pathways toward synthesis of NH3 are generally going downhill under the applied potential of 0 V, and an optimal reduction pathway was screened out with a maximum kinetic barrier of 0.16 eV during the hydrogenation process. The low adsorption free energy of H atom together with the existing relatively higher energy barriers for the formation of N2O/N2 guarantee the hydrogen evolution reaction (HER) and the partial reduction channel are less competitive than NH3 production. These findings enrich the potential application of two dimensional topological materials in electrocatalysis.