Visible light photocatalytic degradation of nitric oxides on PtOx-modified TiO2 via sol–gel and impregnation method

Abstract The visible light active catalysts, PtO x -doped TiO 2 (PtO x –TiO 2 ) and PtO x -loaded TiO 2 (PtO x /TiO 2 ), were successfully synthesized by the acid-catalyzed sol–gel process and the impregnation method. Pt(NH 3 ) 4 (NO 3 ) 2 or H 2 Pt(OH) 6 was employed as the PtO x precursor. By comparing the results of De-NO x , the modified photocatalysts exhibited a higher visible-light-responsive activity, and a lower NO 2 selectivity than the unmodified ones. The FE-SEM images suggested that the particle size was unchanged after modification. The XRD patterns showed that the crystal structure still remained as anatase phase. Nitrogen adsorption revealed no significant change in surface areas for all samples. The UV–vis spectra indicated that PtO x promoted the absorption of visible light. Furthermore, the XPS spectra evidenced that the mixed valence states of PtO–PtO 2 coexisted on the surface of TiO 2 . The adding of PtO x on TiO 2 not only promoted the visible-light-responsive activity of converting NO to NO 2 but also increased the consecutive reaction rate of NO 2 to NO 3 − .