Department of Physics, University of Central Florida, Orlando, FL, 32816, USA.
Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
Nat Commun. 2018 May 15;9(1):1795. doi: 10.1038/s41467-018-04213-9.
Electrochemical reduction of N to NH provides an alternative to the Haber-Bosch process for sustainable, distributed production of NH when powered by renewable electricity. However, the development of such process has been impeded by the lack of efficient electrocatalysts for N reduction. Here we report efficient electroreduction of N to NH on palladium nanoparticles in phosphate buffer solution under ambient conditions, which exhibits high activity and selectivity with an NH yield rate of ~4.5 μg mg h and a Faradaic efficiency of 8.2% at 0.1 V vs. the reversible hydrogen electrode (corresponding to a low overpotential of 56 mV), outperforming other catalysts including gold and platinum. Density functional theory calculations suggest that the unique activity of palladium originates from its balanced hydrogen evolution activity and the Grotthuss-like hydride transfer mechanism on α-palladium hydride that lowers the free energy barrier of N hydrogenation to *NH, the rate-limiting step for NH electrosynthesis.
电化学还原 N 到 NH 为 Haber-Bosch 工艺提供了一种替代方法，用于在可再生电力驱动下，可持续地、分布式地生产 NH。然而，由于缺乏高效的电催化剂用于 N 还原，该过程的发展受到了阻碍。在这里，我们在磷酸盐缓冲溶液中报道了钯纳米粒子在环境条件下高效电还原 N 到 NH，在 0.1 V 对可逆氢电极（对应于 56 mV 的低过电势）下，具有高达~4.5 μg·mg h 的 NH 产率和 8.2%的法拉第效率，优于包括金和铂在内的其他催化剂。密度泛函理论计算表明，钯的独特活性源于其平衡的析氢活性和α-钯氢化物上的类 Grotthuss 氢化物转移机制，该机制降低了 NH 电合成的限速步骤*NH 的 N 氢化自由能垒。
