Figure 3.

The photocatalytic deNOx activity of the prepared samples during UV light irradiation for 30 min followed by turning off light, while NO gas was continuously flowed in the dark for 3 h. a CaAl2O4:(Eu, Nd)/TiO2-xNy composite; b brookite phase TiO2-xNy; c CaAl2O4:(Eu, Nd)/undoped TiO2 (P25) composite.

Li et al. Nanoscale Res Lett 2011 6:5   doi:10.1007/s11671-010-9750-7