A reactor produces a surface corona for emitting UV light and for the production of ozone by passing air or oxygen through the surface corona. The emitted UV light activates a photocatalyst coated on a surface facing a surface with embedded electrodes which generate the surface corona. The photocatalyst is a thin film of nanoparticle TiO.sub.2 with primary particle size of 0.02 to 0.2 .mu.m was deposited on a substrate by a flame aerosol method. The method combines ozonation and photocatalysis to provide effective and efficient oxidation of alcohols and hydrocarbons to value added products. The method can also be used for air and water cleaning.