Volatile organic compound removal by post plasma-catalysis over porous TiO 2 with enriched oxygen vacancies in a dielectric barrier discharge reactor.

Non-thermal plasma (NTP) degradation of volatile organic compounds (VOCs) into CO 2 and H 2 O 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 2 nanocrystals. Vo-poor and Vo-rich TiO 2 catalysts were placed in the back of an NTP reactor to convert harmful ozone molecules into ROS that decompose VOCs via heterogeneous catalytic ozonation processes. The results indicate that Vo-TiO 2 -5/NTP with the highest Vo concentration exhibited superior catalytic activity in the degradation of toluene compared to NTP-only and TiO 2 /NTP, achieving a maximum 96% elimination efficiency and 76% CO x selectivity at an SIE of 540 J L -1 . Mechanistic analysis reveals that the 1 O 2 , ˙O 2 - and ˙OH species derived from the activation of O 3 molecules on Vo sites contribute to the decomposition of toluene over the Vo-rich TiO 2 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 3 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.