Improving photocatalytic activity in NO removal by adding metallic bismuth to SrTiO3 nanoparticles

SrTiO3 and Bi/SrTiO3 were synthesized, and their activities for photocatalytic NO removal with the help of visible light were investigated. The Bi/SrTiO3 shows much higher removal efficiency than that of SrTiO3. For the purpose of manifesting the mechanism of photocatalysis of Bi/SrTiO3, the phase, microstructure, optical, photophysical and photochemical properties of SrTiO3 and Bi/SrTiO3 were investigated. The XRD, TEM and EDS results show that Bi semimetal was deposited on SrTiO3 surface and the deposited Bi nanoparticles have no influence on the phase and microstructure. The DRS and emission show that the deposited Bi nanoparticles lead to the harvest of visible light and remarkable reduction of electron-hole pairs' recombination. The higher photocurrent density of Bi/SrTiO3 suggests that the formation of Bi/SrTiO3 hetero-interface can efficiently enhance the separation rate of electron-hole pairs. These characteristics lead to the higher photocatalytic activity of Bi/SrTiO3. In the photocatalytic removal of NO, center dot OH and center dot O-2(-) active species oxidize NO to nitrate ions through different ways.