Activation of high-energy triple-bonds of N₂ is the most significant bottleneck of ammonia synthesis under ambient conditions. Here, by importing cobalt single clusters as strong electron-donating promoter into the catalyst, the rate-determining step of ammonia synthesis is altered to the subsequent proton addition so that the barrier of N₂ dissociation can be successfully overcome. As revealed by density functional theory calculations, the N₂ dissociation becomes exothermic over the cobalt single cluster upon the strong electron backdonation from metal to the N₂ antibonding orbitals. The energy barrier of the positively shifted rate-determining step is also greatly reduced. At the same time, advanced sampling molecular dynamics simulations indicate a barrier-less process of the N₂ approaching the active sites that greatly facilitates the mass transfer. With suitable thermodynamic and dynamic property, a high ammonia yield rate of 76.2 μg h^–1 mg|$^{-1 }_{\rm cat.}$| and superior Faradaic efficiency of 52.9% were simultaneously achieved.

中文翻译：

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改变钴单簇上的速率决定步骤导致高效的氨合成

N ₂的高能三键的活化是环境条件下氨合成的最重要瓶颈。在这里，通过将钴单簇作为强给电子促进剂导入催化剂中，氨合成的速率决定步骤被改变为随后的质子添加，从而可以成功地克服N ₂解离的障碍。正如密度泛函理论计算所揭示的那样，在从金属到 N ₂的强电子回馈后，N ₂离解在钴单簇上变得放热反键轨道。正向移动的速率决定步骤的能垒也大大降低。同时，先进的采样分子动力学模拟表明 N ₂接近活性位点的无障碍过程极大地促进了传质。具有合适的热力学和动力学性质，氨产率高达 76.2 μg h ^–1  mg |$^{-1 }_{\rm cat.}$| 同时实现了 52.9% 的卓越法拉第效率。