Electrochemical conversion of nitrate to ammonia is an appealing route to efficiently synthesize ammonia under ambient conditions while reducing environmental nitrate pollutants. However, this approach is obstructed by the limited yield and selectivity of ammonia because the electrochemical nitrate-to-ammonia conversion involves multi-electron/proton transfer and faces competition from the hydrogen evolution reaction. Here, we demonstrate a plasmon-assisted strategy to improve the performance of nitrate-to-ammonia electrochemical conversion by constructing plasmonic antenna–reactor catalysts, where Au and Pd nanoparticles/hydrogen substituted graphdiyne (Pd/HsGDY) work as the light antenna and reaction site, respectively. Plasmonic excitation of Au–Pd/HsGDY catalysts can remarkably accelerate the nitrate reduction, with the yield rate, selectivity, and Faradaic efficiency of ammonia respectively increased by 14.3, 2.1, and 1.8 times under optimal conditions. Mechanistic investigations unveil that Au plasmon-induced hot electrons facilitate nitrate-to-ammonia reaction by regulating the adsorption of reaction intermediates on Pd/HsGDY, wherein the rate-determining step was shifted from nitrate adsorption to *NH protonation and the overall apparent activation was reduced. Moreover, hot electrons suppress the competing hydrogen evolution by enlarging the Gibbs free energy of hydrogen formation. These results open a way to develop desirable catalysts for producing value-added ammonia from environmentally hazardous nitrate by a synergistic combination of electricity and light.

中文翻译：

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使用等离子体天线-反应器催化剂进行硝酸盐制氨转化


硝酸盐电化学转化为氨是一种有吸引力的途径，可以在环境条件下高效合成氨，同时减少环境硝酸盐污染物。然而，这种方法受到氨的有限产率和选择性的阻碍，因为电化学硝酸盐到氨的转化涉及多电子/质子转移，并面临来自析氢反应的竞争。在这里，我们展示了一种等离激元辅助策略，通过构建等离子体天线-反应器催化剂来提高硝酸盐到氨电化学转化的性能，其中 Au 和 Pd 纳米颗粒/氢取代石墨二炔 （Pd/HsGDY） 分别作为光天线和反应位点。Au–Pd/HsGDY 催化剂的等离子体激发可以显著加速硝酸盐还原，在最佳条件下，氨的产率、选择性和法拉第效率分别提高了 14.3 倍、2.1 和 1.8 倍。机理研究揭示了 Au 等离激元诱导的热电子通过调节反应中间体在 Pd/HsGDY 上的吸附来促进硝酸盐到氨的反应，其中速率决定步骤从硝酸盐吸附转移到 *NH 质子化，并且整体表观活化降低。此外，热电子通过扩大形成氢的吉布斯自由能来抑制竞争性的析氢。这些结果为开发理想的催化剂开辟了一条道路，通过电和光的协同结合，从对环境有害的硝酸盐中生产增值氨。