Visible light-sensitive yellow TiO 2−xN x and Fe–N co-doped Ti 1−yFe yO 2−xN x anatase photocatalysts

Abstract

Nitrogen substituted yellow colored anatase TiO 2− x N x and Fe–N co-doped Ti 1− y Fe y O 2− x N x have been easily synthesized by novel hydrazine method. White anatase TiO 2− δ and N/Fe–N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994–2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe 3+ in the lattice. TiO 2− x N x has higher conductivity than TiO 2− x and Fe/Fe–N-doped anatase and the UV absorption edge of white TiO 2− x extends in the visible region in N, Fe and Fe–N co-doped TiO 2, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/ T plots for all samples. All TiO 2 and Fe-doped TiO 2 show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe–N-doped TiO 2 consist may cause this discrepancy in their photocatalytic activities.