Effect of Pt or Pd doping on stability of TiO2 nanoparticle suspension in water

Stability of suspensions of TiO2 nanoparticles synthesized by the flame aerosol reactor (FLAR) could be altered by doping TiO2 nanoparticles with Pt, Pd, or Pt–Pd dopants. It was found that doping of TiO2 with Pd or Pt could contribute to the control of the agglomeration of TiO2 suspended in water. With the change of doping content, the isoelectric point (IEP) of stable TiO2 suspension decreased gradually from 5 to 3.6 while the specific surface area was increased from 43.27 to 60.84 m2/g. With pH > 6.0, 2 wt% Pt–Pd/TiO2 suspension exhibited the lowest agglomeration behavior. The plausible intrinsic structures of Pt, Pd, and Pt–Pd doped TiO2 nanoparticles were proposed and discussed with respect to their IEP based on the DLVO theory.