Photocatalytic hydrogen production in the water/methanol system using Pt/RE:NaTaO_3 (RE = Y, La, Ce, Yb) catalysts

摘要

Perovskite type RE-doped NaTaO_3 (where RE represents Rare Earths elements like Y, La, Ce, Yb) catalysts, derived from solid state synthesis method, have been used for the photo-catalytic hydrogen production from water using methanol as sacrificial agent. The pho-tocatalytic activity of NaTaO_3 in H_2 production is improved on its doping with Y, La or Yb elements. In contrast, Ce-doped sample shows a worsening of the photoactivity, which is even lower than the un-doped catalyst. The characterization of the materials reveals that the monoclinic structure and the presence of Ce~(4+) do not favour to increase the performance of NaTaO_3. Previous reports proved that La-doping boosted the water splitting photoactivity of NaTaO_3. However the results of this work reveal an increase in the H_2 production by the use of Y as dopant. This enhancement in the photoactivity could be related with the modification of the opto-electronic properties of NaTaO_3 with the inclusion of RE elements (Y, La, Yb) in the orthorhombic structure of this perovskite. Moreover, the catalytic activity of all the RE-doped samples is further increased on their modification with Pt nanoparticles (NPs) loading that act as photo-generated electron scavenger facilitating the reduction reactions.