Influence of the mixed ratio on the photocurrent of the TiO_2/SnO_2 composite photoelectrodes sensitized by mercurochrome

摘要

The mercurochrome-sensitized TiO_2/SnO_2 composite photoelectrdes with different mixed ratio have been prepared.When the mixed ratio of TiO_2 to SnO_2 was equal to 1:1,the maximal photocurrent was obtained at 0.1V applied potential (versus saturated calomel electrode (SCE)).In the snesitized composite electrodes,the energy barriers formed between TiO_2 and SnO_2 particles have double function:(1) they could reduce the recombination of the photo-induced electrons and the holes in the oxidized mercurochrome,or in the electrolyte (I_3~-),(2) they could alsoblock the transport of the photo-induced electrons to the outer circuit.Spectro-electrochemical(SEC) measurements of the TiO_2,SnO_2 and TiO_2/SnO_2 composite electrode also provided the evidence for the existence of the barriers in the composite electrode. The energy barrier is about 80 mV calculated from the diference in the bleaching width of the SnO_2 and TiO_2/SnO_2 composite electrode.