Towards sustainable plasma gas–liquid nitrogen fixation: research on electrode configuration and reactor reliability

Abstract A double quartz dielectric barrier discharge with water falling film (WF-D-DBD) reactor is designed to reduce electrode galvanic corrosion for longer life. In order to investigate the influence of high-voltage electrode configuration on the synthesis rate and energy consumption of plasma gas–liquid nitrogen fixation, four different external high-voltage electrodes, namely, mesh electrode, sheet electrode, multi-electrode, and copper wire electrode, were studied and dependence of the electrical parameters (e.g., volt-ampere characteristic, dielectric equivalent capacitance, and power factor), the emission spectra on the electrode configuration was obtained. The results show a nitrogen fixation reactor with a mesh-electrode structure can achieve a faster synthesis rate and higher energy efficiency, while the one with the multi-electrode structure can reduce the discharge current and ensure safe operation and long-time running. The selectivity of nitrogen fixation to nitrate was 100% in all four reactors. It is concluded that the production of OH carboxyl groups from water decomposition plays an important role in the reaction, and the presence of hydrogen peroxide and ozone improves the selectivity. The reticulated reactor exhibited the most favorable performance, with synthesis rate of 160.9 μmol min −1 and energy consumption of 43.2 MJ mol −1 . This result is expected to fulfil the need for green, distributed and sustainable nitrogen fixation.