Synergistic plasma-electrocatalytic NH₃synthesis from air enabled by oxygen vacancy-rich MnO_x/TiO₂

Plasma catalytic nitrogen oxidation coupling electrocatalysis for ammonia synthesis is expected to replace energy-intensive Haber-Bosch process. In plasma nitrogen fixation, high-energy electrons collide with N₂ molecules to dissociate them into reactive nitrogen species. However, products from plasma nitrogen fixation (pNF) are mostly insoluble NO, which limits the process of electrocatalysis for ammonia synthesis. In this paper, the oxygen vacancy-rich MnO_x/TiO₂ combined with dielectric barrier discharge (DBD) were applied to effectively regulate the proportion of NO₂ easily dissolved in liquid phase in nitrogen fixation products. It was found that putting 10 % MnO_x/TiO₂ in the discharge gap of the DBD, the NO₂ selectivity was significantly increased from 26.6 % to 81.9 %. XPS confirmed that the 10 % MnO_x/TiO₂ of higher Mn³⁺/Mn ratio and higher surface adsorbed oxygen content were beneficial to the transformation of pNF products into NO₂. The improvement of NO_x⁻greatly improved the efficiency of electrocatalytic ammonia synthesis (The yield of NH₄⁺increased from 2.75 to 14 mg/h). This work provided a valuable solution to promote the industrial application of this process.