The electrochemical N₂ reduction reaction (NRR) represents a green and sustainable route for NH₃ synthesis under ambient conditions. However, the mechanism of N₂ activation in the electrocatalytic NRR remains unclear. Herein, we found that the high spin state Mn³⁺-Mn³⁺ pairs induced by oxygen vacancy in MnO₂ nanosheets greatly enhance the catalytic activities. The strong electron transfer between d orbital of Mn and orbital of N₂ forces the N₂ to be of radical nature, which activates the hydrogenation process and weakens the N≡N bond. Based on the density functional theory (DFT) calculation results, we precisely designed mesoporous MnO₂ nanosheets with rich oxygen vacancies via using methyltriphenylphosphonium bromide (MPB) to induce more Mn³⁺-Mn³⁺ pairs (Mn^3-3-MnO₂), which can achieve a fairly high ammonia yield of up to 147.2 µg·h⁻¹·mg_cat⁻¹. at -0.75 V vs. reversible hydrogen electrode (RHE) and a high Faradaic efficiency (FE) of 11%. Furthermore, these mesoporous MnO₂ nanosheets exhibit the superior durability with negligible changes in both NH₃ yield and FE after a consecutive 6-recycle test and the current density electrolyzed over a 24-hour period. Our findings offer an approach to designing highly active transition metal catalysts for electrocatalytic nitrogen reduction.

电化学 N ₂还原反应 (NRR) 代表了在环境条件下合成NH ₃的绿色可持续途径。然而，电催化NRR中N _{2活化的机制仍不清楚。}在此，我们发现由MnO ₂纳米片中的氧空位诱导的高自旋态Mn ³⁺ -Mn ³⁺对大大提高了催化活性。Mn的d轨道和N ₂的轨道之间的强电子转移迫使N ₂具有自由基性质，可激活氢化过程并削弱 N≡N 键。基于密度泛函理论（DFT）计算结果，我们通过使用甲基三苯基溴化鏻（MPB）诱导更多的Mn ³⁺ -Mn ³⁺对（Mn ^3-3 -MnO ₂）精确设计了具有丰富氧空位的介孔MnO ₂纳米片。 ，可实现高达147.2 µg·h ^-1 ·mg _cat ^-1的相当高的氨产量。在 -0.75 V 与可逆氢电极 (RHE) 和 11% 的高法拉第效率 (FE) 下。此外，这些介孔 MnO ₂纳米片表现出优异的耐久性，而 NH 的变化可以忽略不计。₃连续 6 次循环测试和 24 小时内电解电流密度后的产量和 FE。我们的研究结果提供了一种设计用于电催化氮还原的高活性过渡金属催化剂的方法。