Efficient Ammonia Electrosynthesis from Nitrate on Strained Ruthenium Nanoclusters



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Li, J., Zhan, G., Yang, J., Quan, F., Mao, C., Liu, Y., Wang, B., Lei, F., Li, L., Chan, A., Xu, L., Shi, Y., Du, Y., Hao, W., Wong, P., Wang, J., Dou, S., Zhang, L. & Yu, J. (2020). Efficient Ammonia Electrosynthesis from Nitrate on Strained Ruthenium Nanoclusters. Journal of the American Chemical Society, 142 (15), 7036-7046.


© 2020 American Chemical Society. The limitations of the Haber-Bosch reaction, particularly high-temperature operation, have ignited new interests in low-temperature ammonia-synthesis scenarios. Ambient N2 electroreduction is a compelling alternative but is impeded by a low ammonia production rate (mostly h-1), a small partial current density (cm-2), and a high-selectivity hydrogen-evolving side reaction. Herein, we report that room-temperature nitrate electroreduction catalyzed by strained ruthenium nanoclusters generates ammonia at a higher rate (5.56 mol gcat-1 h-1) than the Haber-Bosch process. The primary contributor to such performance is hydrogen radicals, which are generated by suppressing hydrogen-hydrogen dimerization during water splitting enabled by the tensile lattice strains. The radicals expedite nitrate-to-ammonia conversion by hydrogenating intermediates of the rate-limiting steps at lower kinetic barriers. The strained nanostructures can maintain nearly 100% ammonia-evolving selectivity at >120 mA cm-2 current densities for 100 h due to the robust subsurface Ru-O coordination. These findings highlight the potential of nitrate electroreduction in real-world, low-temperature ammonia synthesis.

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