TiO2-Al2O3 binary mixed oxide surfaces for photocatalytic NO x abatement

TiO2-Al2O3 binary oxide surfaces were utilized in order to develop an alternative photocatalytic NO x abatement approach, where TiO2 sites were used for ambient photocatalytic oxidation of NO with O2 and alumina sites were exploited for NO x storage. Chemical, crystallographic and electronic structure of the TiO2-Al2O3 binary oxide surfaces were characterized (via BET surface area measurements, XRD, Raman spectroscopy and DR-UV-Vis Spectroscopy) as a function of the TiO2 loading in the mixture as well as the calcination temperature used in the synthesis protocol. 0.5 Ti/Al-900 photocatalyst showed remarkable photocatalytic NO x oxidation and storage performance, which was found to be much superior to that of a Degussa P25 industrial benchmark photocatalyst (i.e. 160% higher NO x storage and 55% lower NO2(g) release to the atmosphere). Our results indicate that the onset of the photocatalytic NO x abatement activity is concomitant to the switch between amorphous to a crystalline phase with an electronic band gap within 3.05-3.10eV; where the most active photocatalyst revealed predominantly rutile phase together and anatase as the minority phase.