Balancing N2 Activation in Two-Dimensional Electrides for Ammonia Synthesis

Abstract

Two-dimensional (2D) electrides, featuring interlayer-delocalized anionic electrons, hold promise for N₂ activation but face challenges in catalytic ammonia synthesis due to structural instability under reaction conditions. Here, we introduce a dual-site catalyst using the robust 2D metal carbide Y₂C electride as a platform, where N₂ is activated at electron-rich interlayers and H₂ dissociates on supported Ni nanoparticles, enabling efficient and stable ammonia production. Through Raman spectroscopy, XPS, and DFT calculations, we uncover a scaling relationship for N₂ activation in 2D electrides: intermediate N₂ binding strength correlates with the formation of reactive (N₂)^δ− intermediates, crucial for efficient NH₃ production. Leveraging this insight, La-doped Y₂C (La-Y₂C) optimizes N₂ activation, and the Ni/La-Y₂C catalyst achieves an exceptional activity of 34.6 mmol·g^–1·h^–1 at 400 °C and 1.0 MPa, surpassing reported Ni-based catalysts, the benchmark Cs–Ru/MgO, and industrial wüstite-based Fe under identical conditions. These findings provide a rational framework for designing advanced 2D electrides for controllable N₂ activation and sustainable ammonia synthesis.