Computational investigation of electrocatalytic ammonia synthesis on Mo-doped C24N24 fullerene.

Abstract

Context: The industrial production of ammonia through the Haber-Bosch process is energy intensive and operates under extreme conditions. In contrast, the catalytic reduction of nitrogen (N₂) to ammonia (NH₃) under mild conditions presents a significant challenge with important implications for sustainable chemistry. This work investigates the potential of Mo-doped carbon nitride (C₄₂N₂₄) fullerene as a catalyst for N₂ reduction. The study reveals that Mo@C₄₂N₂₄ exhibits rapid catalytic activity, with a preference for the enzymatic mechanism for N₂ conversion to NH₃. Notably, H₂ evolution is suppressed, making Mo-doped C₄₂N₂₄ a promising candidate for ammonia synthesis under mild conditions.

Methods: Density functional theory (DFT) calculations were performed using the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA) framework. The DNP basis set was employed in all calculations using the DMol³ code. The Mo atom was incorporated into the N₄ cavity of the carbon nitride structure, with a binding energy of - 2.54 eV. The electronic structure was analyzed through molecular electrostatic potential maps, Hirshfeld charge density analysis, and spin density analysis. Three catalytic pathways, alternating, distal, and enzymatic were studied to understand the reaction mechanism. All calculations were carried out using the DMol³ software package.