Electrochemical conversion of CO2 plasmas

The integration of non-thermal CO2 plasma (NTP) with a custom-designed electrolyte-gap electrolyser and CuO catalysts represents an innovative strategy to enhance the electrochemical conversion of CO2 into C1–C3 products. Systematic galvanostatic experiments conducted at current densities ranging from 100 to 225 mA cm-2 demonstrated that plasma-on operation significantly reduces cell voltages (by up to ~1.3 V) and that product selectivity transitions from C1 species (CO and methane) to C2+ products, including ethylene, ethanol, acetate, propylene, and propanol. While CO and H2 predominate under plasma-off conditions, with limited formation of C2 products, the hybrid plasma–electrochemical system increases the Faradaic efficiency (FE) for ethylene up to 39.5% and ethanol up to 18.1%. These enhancements are attributed to plasma-generated reactive species (radicals and excited-state molecules) that lower kinetic barriers for C–C coupling and modify the interfacial pH, thereby reducing parasitic carbonate/bicarbonate losses. The plasma-on state resulted in a statistically significant increase in liquid product carbon efficiency (from an average of ~0.41% during plasma-off experiments to ~0.91% during plasma-on experiments). Although the system currently exhibits lower overall energy efficiency owing to the power demands of the plasma discharge, this work establishes a robust framework for flexible product tuning and sustainable carbon utilisation via plasma-activated feeds.

非热CO₂等离子体（NTP）与定制化电解质间隙电解槽及氧化铜（CuO）催化剂的集成联用，为强化CO₂电化学转化生成C1~C3产物提供了一种创新策略。在100~225 mA cm⁻²的电流密度范围内开展的系统性恒电流实验表明，等离子体开启工况可显著降低电池电压（降幅最高可达约1.3 V），且产物选择性从C1产物（一氧化碳与甲烷）向C2+产物（包括乙烯、乙醇、乙酸盐、丙烯与丙醇）转变。等离子体关闭工况下，产物以一氧化碳与氢气为主，C2产物生成量有限；而该等离子体-电化学混合体系可将乙烯的法拉第效率（FE）提升至39.5%，乙醇的法拉第效率提升至18.1%。上述性能提升可归因于等离子体产生的活性物种（自由基与激发态分子）：其可降低C-C偶联的动力学能垒并调控界面pH，从而减少副反应碳酸盐/碳酸氢盐的损耗。等离子体开启工况可使液态产物碳效率实现统计学意义上的显著提升——从等离子体关闭实验中的平均约0.41%增至等离子体开启实验中的约0.91%。尽管受等离子体放电的功率需求限制，该体系目前的整体能源效率仍偏低，但本研究为通过等离子体活化进料实现灵活的产物调控与可持续碳利用构建了一套可靠的研究框架。