Electrochemical ammonia synthesis by reduction of nitrate on Au doped Cu nanowires.

Electrochemical nitrate reduction reaction (NO RR) to synthesize valuable ammonia (NH) is considered as a green and appealing alternative to enable an artificial nitrogen cycle. However, as there are other NO RR pathways present, selectively guiding the reaction pathway towards NH is currently challenged by the lack of efficient catalyst. Here, we demonstrate a novel electrocatalyst for NO RR consisting of Au doped Cu nanowires on a copper foam (CF) electrode (Au-Cu NWs/CF), which delivers a remarkable NH yield rate of 5336.0 ± 159.2 μg h cm and an exceptional faradaic efficiency (FE) of 84.1 ± 1.0% at -1.05 V ( RHE). The N isotopic labelling experiments confirm that the yielded NH is indeed from the Au-Cu NWs/CF catalyzed NO RR process. The XPS analysis and infrared spectroscopy (IR) spectroscopy characterization results indicated that the electron transfer between the Cu and Au interface and oxygen vacancy synergistically decreased the reduction reaction barrier and inhibited the generation of hydrogen in the competitive reaction, resulting in a high conversion, selectivity and FE for NO RR. This work not only develops a powerful strategy for the rational design of robust and efficient catalysts by defect engineering, but also provides new insights for selective nitrate electroreduction to NH.