Relationship between the electric structures calculated by the first principles calculation method and the photoelectrocatalysis degradation of Ir-doped SnO2 electrodes

Abstract

DSA-type Ti/IrxSn1-xO2 electrodes were prepared by thermal decomposition method. The first-principles calculations were employed to study the effects of the doping element and its content to the main oxides on the relationship between the electronic structures and the photoelectrocatalytic(PEC) activity of Ti/IrxSn1-xO2 electrodes. The performance of the coatings was characterized using XRD, XPS, LSV and EIS. The results showed that: the band gap decreased with the increase of Ir content. An impurity level appeared in the forbidden band, which was conducive to the separation of photogenerated electrons and holes, improving the conductivity and photocatalytic activity of the electrodes. However, the excessive content of Ir would promote the recombination of electrons and holes and reduce the band gap. When the Ir content was above 25%, the forbidden band of the oxide coating could disappeare. The conductivity of the coating further improved, it sacrificed the photogenerated carriers and thus reduced photocatalytic activity of the electrode. Besides, reducing band gap would weaken the redox ability of photo generated electron-hole pair. Therefore, The PEC activity of the Ti/IrxSn1-xO2 electrodes was mainly depened on the effects of Ir content on the electronic structures of the IrxSn1-xO2 coatings. In our experiments, the Ti/Ir0.0625Sn0.9375O2 electrode exhibited better PEC properties.