This positive impact may be driven by two phenomena: (1) the high-energy electron generated by plasma may favor the desorption of intermediate products of oxidation,leading to the catalytic sites turn-over increase and (2) the ozone, produced by the plasma,can be activated on the photocatalyst by the photogenerated charges or/and can be activated on the manganese oxide surface. This latter phenomenon could explain the observed relationship between the ethanol conversion increase and the ozone concentration decrease (Table 2). There are several possible ozone depletion mechanisms to explain the observed behavior: