Stimulated by the growing demand for sustainable and/or economical distributed ammonia synthesis, the electrochemical nitrogen reduction reaction has attracted considerable interest. The nitrogen-containing impurities in commercial metal-based nitrogen reduction reaction catalysts such as metal oxides and metallic irons have, however, been overlooked. Herein we report the presence of nitrogen-containing species in NO_x⁻ or nitrides at substantial levels revealed from many commercial catalysts. We call attention to the necessity to screen the NO_x⁻/nitrides impurities in commercial catalysts, as the nitrogen impurities are not commonly listed in vendors’ assay documents. A simple two-step procedure (alkaline/acidic treatment followed by HPLC/UV–vis analysis) is recommended as a reliable protocol for screening NO_x⁻/nitrides impurities in catalyst materials. A case analysis is also carried out on the previously reported H₂O–NaOH–KOH system with both ¹⁵N-isotopic labelling and nitrogen elemental tracking, reassigning the true nitrogen source of the electrochemically produced NH₃ from gaseous N₂ to nitrogen-containing impurities in catalysts.

由于对可持续和/或经济的分布式氨合成的需求不断增长，电化学氮还原反应引起了人们的极大兴趣。然而，商业金属基氮还原反应催化剂中的含氮杂质，例如金属氧化物和金属铁，已被忽略。在这里，我们报告中的NO含氮物质的存在_X ^-或在相当水平的氮化物从许多商业催化剂透露。我们提请您注意筛选NO _x的必要性^-商用催化剂中的/氮化物杂质，因为氮杂质通常未在供应商的测定文件中列出。一个简单的两步法（碱性/酸性处理然后通过HPLC / UV-VIS分析）被推荐为用于筛选NO一个可靠的协议_X ^-在催化剂材料/氮化物的杂质。还对先前报道的具有¹⁵ N同位素标记和氮元素追踪的H ₂ O–NaOH–KOH系统进行了案例分析，将电化学生成的NH ₃的真实氮源从气态N ₂重新分配为含氮催化剂中的杂质。