Deep Oxidation of NO by a Hybrid System of Plasma-N-Type Semiconductors: High-Energy Electron-Activated Pseudo Photocatalysis Behavior

A pseudo photocatalysis process, being initiated between plasma and N-type semiconductors in the absence of light, was investigated for NO removal for the first time via dynamic probing of reaction processes by FT-IR spectra. It was demonstrated that N-type semiconductor catalysts could be activated to produce electron-hole (e(-)-h(+)) pairs by the collision of high-energy electrons (e*) from plasma. Due to the synergy of plasma and N-type semiconductors, major changes were noted in the conversion pathways and products. NO can be directly converted to NO(2)(- )and NO3- instead of toxic NO2, owing to the formation of O-2(-) and center dot OH present in catalysts. New species like O-3 or center dot O may be generated from the interaction between catalyst-induced species and radicals in plasma at a higher SIE, leading to deep oxidation of existing NO2 to NO2O5. Experiments with added trapping agents confirmed the contribution of e(-) and h(+) from catalysts. A series of possible reactions were proposed to describe reaction pathways and the mechanism of this synergistic effect. We established a novel system and realized an e*-activated pseudo photocatalysis behavior, facilitating the deep degradation of NO. We expect that this new strategy would provide a new idea for in-depth analysis of plasma-activated catalysis phenomenon.