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Low-Coordinated Gold Atoms Boost Electrochemical Nitrogen Reduction Reaction under Ambient Conditions

Zhang, Kai, Guo, Ruijie, Pang, Fangjie, He, Jia, Zhang, Weiqing
ACS sustainable chemistry & engineering 2019 v.7 no.12 pp. 10214-10220
ambient temperature, ammonia, catalysts, catalytic activity, electrochemistry, geometry, gold, nanogold, nanopores, nitrogen
Exploration of efficient catalysts is a priority for the electrochemical nitrogen reduction reaction (NRR) under ambient temperature and pressure. Recently, several nanostructured gold (Au) catalysts have shown impressive catalytic activities toward NRR. However, the atomic origin of high catalytic activities of Au catalysts is vague. In this work, a quantitative relationship between the generalized coordination number (GCN) and NRR activity is established. In particular, the NRR activity is linearly increased with the decrease of GCN values of Au surface atoms. As a proof-of-concept experiment, the NRR activity of nanoporous gold (NPG) with a high proportion of low-coordinated surface atoms is investigated and compared with that of Au octahedra (OCTA) enclosed with (111) facets. As expected, NPG exhibits a high NH₃ production rate of 30.5 μg h–¹ mg–¹, which is 5.8 times larger than that of Au OCTA. In addition, the excellent catalytic performance of NPG can be retained for 21 h by showing constant current density, NH₃ production rate, and faradaic efficiency. The findings in this work would provide guiding principles for designing efficient NRR catalysts.