ZrN6-Doped Graphene for Ammonia Synthesis: A Density Functional Theory Study

Considering the pivotal role of ammonia in the modern chemical industry, designing effective catalysts for the N₂-to-NH₃ conversion stimulates great research enthusiasms. In this work, by means of density functional theory calculations, we systematically investigated the electrocatalysis of six-coordinated transition metal atom anchored graphene for nitrogen fixation. The free energy analysis shows that the ZrN₆ configuration has a good activity toward ammonia synthesis under overpotential of 0.51 V. According to the electron transfer analysis, ZrN₆ site plays a bridging role in charge transfer between the functional graphene and the reactant. Furthermore, the presence of N₆ coordination increases the electron accumulation on the NNH_x intermediates, which weakens the intermolecular N−N bond, reducing the thermodynamic barrier of protonation process. This work provides a basic understanding of the interaction between transition metal and the adjacent coordination in tuning the reactivity.