A high yield, low energy synthesis of carbon nano‐onions (CNOs) by electrolysis of CO₂ in molten carbonate is presented. Carbon nano‐onions are a recently recognized, less studied morphology of carbon nanomaterials consisting of nested concentric carbon spheroids. Previously, a high yield growth of carbon nanotubes by CO₂ electrolysis in molten carbonate was achieved through transition metal nucleation points on the electrolysis cathode. Here, effective low energy CNO synthesis from CO₂ is achieved instead by excluding those nucleating agents from the molten carbonate growth medium resulting in a profusion of uniform CNOs, with an increasing diameter correlated to increasing growth time. CO₂ transformation to valuable materials, such as CNOs, adds value to CO₂ to incentivize consumption of this greenhouse pollutant. For example, CNOs are currently valued 20 000 times higher than coal.

中文翻译：

---

熔融电解直接由CO2制成的碳纳米洋葱用于缓解温室气体

提出了通过在熔融碳酸盐中电解CO _2的高产率，低能量合成碳纳米洋葱（CNOs）的方法。碳纳米洋葱是由嵌套同心碳球体组成的碳纳米材料的一种最近才被人们认识的，研究较少的形态。以前，通过在电解阴极上的过渡金属成核点实现了在熔融碳酸盐中通过CO ₂电解实现碳纳米管的高产率增长。在此，通过从熔融碳酸盐生长介质中排除那些成核剂，从而导致均匀的CNO大量堆积，而实现了由CO _2进行有效的低能CNO合成，而直径的增加与生长时间的增加相关。一氧化碳₂向有价值的材料（如CNOs）的转化增加了CO _2的价值，从而刺激了这种温室污染物的消耗。例如，目前CNO的价值是煤炭的2万倍。