Nitrogen fixation by atmospheric microwave plasma with local electric field enhancement

Abstract Nitrogen fixation by atmospheric microwave plasma is a promising green technology. However, the energy consumption (EC) of nitrogen fixation driven by microwave plasma is still too high in existing reports, and there is a lack of effective methods to reduce it. In this paper, a method of local electric field enhancement (LEFE) in atmospheric microwave plasma is reported, which is achieved in an optimized metal array structure that can increase the electric field intensity by 385 times. The experimental results show that the reduction of EC reaches up to 20% and the nitrogen oxide production increases by up to 26% with the LEFE. The achieved EC is as low as 1.78 MJ mol −1 with a corresponding nitrogen oxide production of 3.53%. To the best of our knowledge, this is the first study to explore the role of LEFE on nitrogen fixation, and the EC in this study is the lowest among the existing studies of nitrogen fixation by atmospheric pressure microwave air plasma.