Conversion of Dinitrogen to Ammonia
【摘要】：Dinitrogen is abundant in atmosphere, yet it can merely be utilized directly by a few organisms with endophytic diazotrophic bacteria.Nitrogen fixation is one of the most important issues but a long-standing challenge in chemistry. Here, we propose Fe/BN and V/BN as the catalyst for nitrogen fixation from first principles calculations. To obtain information details of the conversion of the activated dinitrogen to ammonia on this Two-dimensional material, we calculated the key reaction steps and products during the conversion process and canvassed the distal, alternating mechanisms proposed previously. Two feasible reaction pathways,plus a hybrid path, were revealed and their schematic diagrams are illustrated in this graph. One can see in distal pathway that the consecutive protonation occurs first at the distal-N and then the proximal-N. The successive 1→ 4 steps result in the full scission of N-N bond and release an NH_3, while the second NH_3 is released in the subsequent 5 → 7 steps and the Fe-N_2 is regenerated,indicating the feasibility of the cycle of adsorbing N_2 and releasing NH_3. While, for the alternating pathways, the protonation alternates between the two N atoms, making the first NH_3 release at the 6th step. The red arrow represents the hybrid path that transforms from distal to alternating pathway. Through the Fe, V single metal atoms doping, narrowing the band gap, change the two-dimensional BN material electronic structure and conductivity.