Coated substrates having undercoating layers that exhibit improved photocatalytic activity

A coated substrate comprising: a glass substrate; an undercoat coating comprising at least one selected from (a) a mixture of silica and zirconia comprising 60 to 95 volume% silica Y on 40 layer 5% by volume of zirconium oxide having a thickness in the range of 10 nm to 150 nm, (b) a mixture of silica and alumina comprising 50 to 99 volume% silica and 50 al1 vol% alumina and having a thickness in the range of 10 nm to 150 nm; or (c) a mixture of silica, alumina and titania comprising 30 to 80% by desílice volume, 1 to 15% by volume of alumina and 69 to 5% by volume of titania and unespesor in the range of 10 nm to 150 nm, which covers at least a portion of the substrate; yun photocatalytic functional coating covering at least part of the subcoating layer, consisting of the functional coating titanium oxide, wherein the subcoating layer and the photocatalytic functional layer are deposited by SomeProcedure CVD type, in which the coated substrate has the following reflected color coordinates according to elcie 1967, as measured from the coated side: a * ranging from -10 to 0; b * between -15 y0; and L * between 44 and 54.