Patent ID: 7294404

Claim:
A substrate bearing a photocatalytic coating comprising, in sequence outwardly: a) a first graded film region having a substantially continuously decreasing concentration of a first transparent dielectric material and a substantially continuously increasing concentration of a second transparent dielectric material; b) a second graded film region having a substantially continuously decreasing concentration of the second transparent dielectric material and a substantially continuously increasing concentration of a third transparent dielectric material, the third transparent dielectric material comprising a photocatalyst; and wherein the coating consists essentially of film regions of different transparent dielectric materials interlocked by continuous transition, and the coating does not include any discrete film interfaces, the coating comprising a homogenous intermediate film region that is bounded by and gradually transitions into the first and second graded film regions, the homogenous intermediate film region having a thickness and comprising said second transparent dielectric material, the homogenous intermediate film region having a composition that is substantially uniform across its thickness.