(446a) When Metal Meets Boron: Cooperative Catalysis for High Efficiency Electro-Synthesis of Ammonia

Ammonia synthesis from the Haber-Bosch process is the most source of artificial fertilizers today. However, this process requires high temperature and pressure, resulting in high energy consumption and large carbon dioxide emission. Electrocatalytic nitrogen reduction reaction (NRR), directly converting electricity into chemical energy carriers, holds great promising next-generation route for ammonia synthesis to replace the Haber-Bosch process. The most challenge in electrocatalytic NRR is still focused on the rational design of a highly active catalyst based on the catalytic mechanism. Here, we reported metal decorated boron-based materials for electrocatalytic NRR. The metal-free boron-based materials were first investigated, and the results illustrated that the N₂ molecule can be sufficiently activated at the boron sites through the “acceptance-donation” process, and the intermediate species (*N, *NH) can transfer to the formed boron hydride (B-H) sites for further hydrogenation. After decoration of Fe nanoparticles onto boron-based materials, Fe species can further adsorb N₂ molecule to lower the activation energy of NºN and increase the yield of NH₃. If a metal that can also form metal hydride was used as co-catalyst, e.g., Sn, the Sn hydride (Sn-H) and B-H sites both can crossly offer proton to the intermediate species that adsorbed on B and Sn sites, which further reduce the overpotential for NRR and enhance the yield of NH₃ compared to Fe decorated B catalysts. Our work on these metal decorated boron-based catalysts provides a new insight into the reaction mechanism of electrochemical synthesis of ammonia.