Effect of Synthesis Methods on the Photocatalytic DeNO_x Activity of CaAl₂O₄:(Eu, Nd)/TiO_2−xN_y Composites

CaAl₂O₄:(Eu,Nd)/TiO_2−xN_y composites were synthesized via two different methods, i.e., a two-step method (solvothermal reaction followed by mechanochemical treatment) and a one-step method (direct solvothermal dispersion method), and the photocatalytic activities were evaluated for deNO_x ability both under UV light (λ>290 nm) irradiation and after turning off the UV light. It was confirmed that TiO_2−xN_y nanoparticles with anatase phase could be uniformly dispersed on the surface of CaAl₂O₄:(Eu, Nd) by both method. However, the composites prepared by a one-step method possessed much larger specific surface areas, higher photocatalytic activity and more prolonged catalytic time after turning off the light than those by a two-step method, indicating that the solvothermal method is more appropriate for the synthesis of CaAl₂O₄:(Eu, Nd)/TiO_2−xN_y composite photocatalyst.