Mo-embedded Ir-based electrocatalyst for nitrogen reduction reaction: A computational study

Abstract

Ammonia has a wide range of applications, including as a fertilizer and important chemical feedstock. Therefore, its catalytic synthesis is critical to global agricultural and industrial production. A widely used method of NH3 synthesis in industry is the Haber–Bosch process. However, the energy consumption of this process is high, making it an environmentally unfriendly technology. As a result, methods for NH3 synthesis at room temperature and pressure are urgently required. The electrocatalytic nitrogen reduction reaction (NRR) is widely regarded as a green and sustainable method for NH3 production because the reaction can be carried out under ambient conditions, and the electricity required to drive the reaction can be generated from renewable resources. In this work, an NRR catalyst based on Ir doped with Mo was modeled using density functional theory calculations, and the effect of the degree of doping on the catalytic activity was investigated. We found that the Ir(100) surface doped with a single Mo atom and that doped with two adjacent Mo atoms (Mo@Ir(100) and Mo@Ir(100)-ortho, respectively) exhibit the best NRR catalytic activities, having free energy barriers of 0.54 and 0.57 eV, respectively. In addition, by comparing the strength of adsorption of N2 and H on the active sites, we found that the competitive hydrogen evolution reaction could be inhibited. These results suggest that Mo@Ir(100) and Mo@Ir(100)-ortho are promising NRR catalysts for use under ambient conditions.