Volatile organic compound removal by post plasma-catalysis over porous TiO with enriched oxygen vacancies in a dielectric barrier discharge reactor.

Non-thermal plasma (NTP) degradation of volatile organic compounds (VOCs) into CO and HO is a promising strategy for addressing ever-growing environment pollution. However, its practical implementation is hindered by low conversion efficiency and emissions of noxious by-products. Herein, an advanced low-oxygen-pressure calcination process is developed to fine-tune the oxygen vacancy concentration of MOF-derived TiO nanocrystals. Vo-poor and Vo-rich TiO catalysts were placed in the back of an NTP reactor to convert harmful ozone molecules into ROS that decompose VOCs heterogeneous catalytic ozonation processes. The results indicate that Vo-TiO-5/NTP with the highest Vo concentration exhibited superior catalytic activity in the degradation of toluene compared to NTP-only and TiO/NTP, achieving a maximum 96% elimination efficiency and 76% CO selectivity at an SIE of 540 J L. Mechanistic analysis reveals that the O, ˙O and ˙OH species derived from the activation of O molecules on Vo sites contribute to the decomposition of toluene over the Vo-rich TiO surface. With the aid of advanced characterization and density functional theory calculations, the roles of oxygen vacancies in manipulating the synergistic capability of post-NTP systems were explored, and were attributed to increased O adsorption ability and enhanced charge transfer dynamics. This work presents novel insights into the design of high-efficiency NTP catalysts structured with active Vo sites.