The graphene-supported transition metal cluster as efficient electrocatalyst for nitrogen reduction reaction

Abstract

NH₃ is the most basic raw material in industrial and agricultural production, and it is also an excellent hydrogen carrier. The high energy consumption and pollution of traditional NH₃ synthesis methods limit their further development. As an environmentally friendly and efficient industrial technology, electrocatalysis has important application value in the field of green energy storage and conversion. Therefore, the development of electrocatalysts with high activity, good stability and low cost is the key to improve the efficiency of the nitrogen reduction reaction (NRR) to generate NH₃. Herein, a series of transition metal clusters loaded onto the di-vacancy graphene (X_mY_n@Gra(X, Y = Fe, Co and Ni; m + n = 3)) as electrocatalysts were designed. By calculating the free energy of the first and last hydrogenation steps, it was found that NiCo₂@Gra and FeCo₂@Gra had the best catalytic activity. The first hydrogenation process from *N₂ to *N₂H was potential-determining step, and the corresponding limiting potentials were − 0.57 and − 0.51 V, respectively. In addition, the reasons for the high catalytic activity of NiCo₂@Gra and FeCo₂@Gra were further elucidated by analyzing the electronic properties. This study provides a new strategy for the use of cluster catalysts in NRR process and a new idea for the fixation and conversion of N₂.