A 2D Ba₂N Electride for Transition Metal-Free N₂ Dissociation under Mild Conditions

Abstract

N 2 activation is a key step in the industrial synthesis of ammonia and other high-value-added N-containing chemicals, and typically is heavily reliant on transition metal (TM) sites as active centers to reduce the large activation energy barrier for N 2 dissociation. In the present work, we report that a 2D electride of Ba 2 N with anionic electrons in the interlayer spacings works efficiently for TM-free N 2 dissociation under mild conditions. The interlayer electrons significantly boost N 2 dissociation with a very small activation energy of 35 kJ mol −1 , as confirmed by the N 2 isotopic exchange reaction. The reaction of anionic electrons with N 2 molecules stabilizes (N 2 ) 2− anions, the so-called diazenide, in the large interlayer space (∼4.5 Å) sandwiched by 2 cationic slabs of Ba 2 N as the main intermediate.

Predicted High-Energy Density MN8 Containing Anionic 18-Crown-6 Ring-Based Polynitrogen Monolayers Acting as Cryptand

“…Molecular, one-dimensional, and few two-dimensional polynitrogen networks have been predicted. Among them, a few being successfully synthesized (e.g., TiN 2 , MgN 4 , BaN 2 , and KN 8 ), although most have not yet been discovered experimentally by high-temperature/high-pressure (HT/HP) techniques.…”

BaCu, a Two-Dimensional Electride with Cu Anions

“…With the surge of interest in the exploration of 2D materials and the excellent physical properties of 2D electrides, efforts are being made to find new 2D electrides and explore their potential applications. ,− Since the experimental discovery of Ca 2 N electride ([Ca 2 N] + ·e – ) with anti-CdCl 2 -type structure, the design and synthesis of 2D electrides are mostly focused on the A 2 B-type structure. A large number of 2D electrides with anti-CdCl 2 structure (A = Ca, Sr, and Ba; B = N, P, As, and Sb) are discovered and extended to the rare--based 2D electrides with significant increases in chemical stability and electron concentration (e.g., [Y 2 C] 2+ ·e 2– ). ,,, From these studies, we find that changes in cations of electrides can produce intriguing electronic properties, ranging from semimetallic Y 2 C and metallic Gd 2 C to semiconducting Sc 2 C .…”