The present application relates to an apparatus for the generation, transmission, distribution and/or usage of electrical energy, the apparatus including a housing enclosing an insulation space and an electrically conductive part arranged in the insulation space, wherein the insulating space contains a dielectric fluid including carbon dioxide and oxygen. In the apparatus an oxidation catalyst is arranged that includes noble metal particles coated onto or embedded into a carrier and serves for the catalytic oxidation of carbon monoxide to carbon dioxide.