Direct electrochemical nitrate reduction to ammonia (NRA) synthesis is an efficient and environmentally friendly production technology. However, the development of highly selective electrocatalysts is still a challenge due to the nine-proton and eight-electron reduction reaction. High-entropy alloys (HEAs) contain a wide range of elements and have adjustable properties, giving them excellent application potential in multi-step reactions. In this work, we skillfully use the local high temperature and excellent thermal conductivity generated at the reduced graphene oxide (rGO) defect in a microwave process to achieve a rapid quenching process in 10 seconds. This approach overcomes element immiscibility and results in a self-supported, single-phase, non-precious metal and uniform FeCoNiCuSn alloy electrode. The HEAs reach a remarkable NH₃ yield of 883.7 ± 11.2 μg h⁻¹ cm⁻², maximum faradaic efficiency (FE) of 94.5 ± 1.4%, and highest NH₃ selectivity of 90.4 ± 2.7%. Experimental and theoretical calculations reveal that the presence of multiple adjacent elements in HEAs triggers a synergistic catalytic effect, while the excellent mass and charge transfer properties of rGO jointly encourage the performance of the electrochemical NRA. In particular, NO₃⁻ favors vertical adsorption at Fe–Fe sites, and the desorption of NH₃ is identified as the rate-determining step (RDS) with an extremely small ΔG value of 0.7 eV.

中文翻译：

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微波辅助制备自支撑石墨烯基高熵合金电极，用于高效、稳定的电催化硝酸盐还原成氨


直接电化学硝酸盐还原制氨 （NRA） 合成是一种高效且环保的生产技术。然而，由于九质子和八电子还原反应，高选择性电催化剂的开发仍然是一个挑战。高熵合金 （HEA） 包含多种元素并具有可调节的性能，使其在多步反应中具有出色的应用潜力。在这项工作中，我们巧妙地利用微波工艺中还原氧化石墨烯 （rGO） 缺陷处产生的局部高温和优异的热导率，实现了 10 秒的快速淬火过程。这种方法克服了元件的不混溶性，并产生了自支撑、单相、非贵金属和均匀的 FeCoNiCuSn 合金电极。高熵离子剂达到了 883.7 ± 11.2 μg ^{h-1 cm-2} 的显著 NH₃ 产量，最大法拉第效率 （FE） 为 94.5 ± 1.4%，最高 NH₃ 选择性为 90.4 ± 2.7%。实验和理论计算表明，高熵合金中多种相邻元素的存在会触发协同催化效应，而 rGO 优异的质量和电荷转移特性共同促进了电化学 NRA 的性能。特别是，NO₃⁻ 有利于 Fe-Fe 位点的垂直吸附，NH₃ 的解吸被确定为速率决定步骤 （RDS），具有 0.7 eV 的极小 ΔG 值。