The prevalent catalysts for natural and artificial N₂ fixation are known to hinge upon transition-metal (TM) elements. Herein, we demonstrate by density functional theory that Al-doped graphene is a potential non-TM catalyst to convert N₂ to NH₃ in the presence of relatively mild proton/electron sources. In the integrated structure of the catalyst, the Al atom serves as a binding site and catalytic center while the graphene framework serves as an electron buffer during the successive proton/electron additions to N₂ and its various downstream N_xH_y intermediates. The initial hydrogenation of N₂ can readily take place via an internal H-transfer process with the assistance of a Li⁺ ion as an additive. In view of the recurrence of H transfer in the first step of N₂ reduction observed in biological nitrogenases and other synthetic catalysts, this finding highlights the significance of heteroatom-assisted H transfer in the design of synthetic catalysts for N₂ fixation.

中文翻译：

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N ₂还原为NH _3的非过渡金属催化体系：Al掺杂石墨烯的密度泛函理论研究

已知用于天然和人工N ₂固定的普遍催化剂取决于过渡金属（TM）元素。在本文中，我们通过密度泛函理论证明，在相对温和的质子/电子源存在下，Al掺杂的石墨烯是一种潜在的非TM催化剂，可将N ₂转化为NH ₃。在催化剂的整体结构中，在连续向N ₂及其各种下游N _x H _y中间质子/电子添加过程中，Al原子充当结合位点和催化中心，而石墨烯骨架充当电子缓冲剂。N ₂的初始氢化借助Li ⁺离子作为添加剂，可以通过内部的H转移过程轻松地发生氢键。考虑到在生物固氮酶和其他合成催化剂中观察到的N ₂还原第一步中H转移的重复发生，这一发现凸显了杂原子辅助H转移在N ₂固定合成催化剂设计中的重要性。