Nonthermal Plasma Catalysis for Toluene Decomposition over BaTiO3-based Catalysts by Ce Doping at A-sites: The Role of Surface-Reactive Oxygen Species

Abstract The insights on the primary surface-reactive oxygen species and their relation with lattice defects is essential for designing catalysts for plasma-catalytic reactions. Herein, a series of Ba1-xCexTiO3 perovskite catalysts with high specific surface areas (68.6 – 85.6 m2 g−1) were prepared by a facile in-situ Ce-doping strategy and investigated to catalytically decompose toluene. Combining the catalysts with a nonthermal plasma produced a significant synergy effect. The highest decomposition efficiency (100%), COx selectivity (98.1%), CO2 selectivity (63.9%), and the lowest O3 production (0 ppm) were obtained when BC4T (Ce/Ti molar ratio = 4:100) was packed in a coaxial dielectric barrier discharge reactor at a specific input energy of 508.8 J L−1. The H2-TPR, temperature-programmed Raman spectra, EPR and OSC results suggested that superoxides (•O2−) were the primary reactive oxygen species and were reversibly generated on the perovskite surface. Molecular O2 was adsorbed and activated at the active sites (Ti3+-VO) via an electron transfer process to form •O2−. Surface-adsorbed •O2− had a greater effect on the heterogeneous surface plasma reactions than the dielectric constant, and enhanced the toluene decomposition and intermediate oxidation. A possible reaction path of toluene decomposition was also proposed.