Carbon dioxide conversion enhanced by local electric field enhancement in atmospheric microwave plasma

Abstract Microwave plasma-driven carbon dioxide (CO 2 ) conversion has gained considerable interest as a promising strategy for mitigating environmental issues and recycling carbon resources, as it enables the conversion of CO 2 into value-added chemicals. However, conventional atmospheric microwave plasma systems encounter the challenge of simultaneously achieving high CO 2 conversion efficiency and energy efficiency. Existing solutions to this problem often involve high operating costs or complex system configurations, resulting in unsatisfactory feasibility. In this study, a local electric field enhancement (LEFE) approach is developed in an atmospheric microwave plasma reactor to enhance the CO 2 conversion. Through the derivation of the LEFE theory for plane electromagnetic waves in a metal rod structure and the finite element method-based simulation of the structure, the optimized metal rod structure enhances the peak and average electric field intensities within the plasma zone by factors of approximately 115 and 4, respectively, compared to those without the metal structure. Experimental results demonstrate that our LEFE method efficiently improves both CO 2 conversion and energy efficiency compared to the case without LEFE under identical processing conditions. The maximum achieved CO 2 conversion efficiency and energy efficiency are 34.1% and 43.1%, respectively. Given its simple structure and low cost, this approach shows significant potential for industrial applications.