Patent ID: 8097340

Claim:
A coated substrate comprising: a glass substrate; at least one undercoating layer consisting essentially of a mixture of silica and alumina or a mixture of silica and zirconia, wherein the undercoating layer is selected from the group consisting of: (a) a mixture of silica and alumina having a molar ratio of about 4 moles of silica to about 1 mole of alumina; and (b) a mixture of silica and zirconia having a molar ratio of about 8 to about 20 moles of silica to about 1 mole of zirconia; and a photocatalytic functional coating overlaying at least a portion of the undercoating layer, wherein the photocatalytic functional coating comprises titania, and wherein the coated substrate with the undercoating layer has a higher photocatalytic activity than without the undercoating layer.