Patent ID: 7156966

Claim:
A NOx-decomposing electrode for reducing NOx or decomposing to NOx to produce oxygen, said NOx-decomposing electrode comprising a plurality of cermet electrode layers each of which comprises an alloy of Pt—Rh and a ceramic component, a first of said cermet electrode layers being formed on a ceramic substrate, and a second of said cermet electrode layers being formed on said first cermet electrode layer, wherein said respective cermet electrode layers have different ratios between said alloy of Pt—Rh and said ceramic component, wherein said ratio between said alloy of Pt—Rh and said ceramic component in said first cermet electrode layer ranges from 20:80 to 50:50 by volume ratio, wherein said ratio between said alloy of Pt—Rh and said ceramic component in said second cermet electrode layer ranges from 60:40 to 50:50 by volume ratio, and wherein proportions of said alloy of Pt—Rh in said respective cermet electrode layers are established such that said proportion is minimum in said first cermet electrode layer, which is a lowermost layer of said electrode, and maximum in said second cermet electrode layer, which is an uppermost layer of said electrode.