Photocatalytic Steam Reforming of Methane over Sodium Tantalate

Abstract

Photocatalytic steam reforming of methane (CH4 + 2H2O → 4H2 + CO2) was examined over modified and unmodified sodium tantalate photocatalysts around room temperature. The activity of the photocatalysts was much influenced by metal cation doped into the bulk of NaTaO3, the crystallites size of NaTaO3, and metal nanoparticles loaded on the surface. The highest activity was obtained over the NaTaO3 doped with La3+, where a moderate amount of La3+ should substitute for Na+ without distorting the crystal structure of NaTaO3. The large crystallites size was a more important factor than the high surface area for higher photocatalytic activity of NaTaO3:La. These factors such as doping and large crystallites should increase the density and the mobility of the photoexcited carriers to improve the intrinsic photocatalytic activity. A moderate amount of Pt nanoparticles loaded on NaTaO3:La most enhanced the activity among the examined metal particles, which would contribute to not only separation of excited electrons...