| Ferroelectric materials are characterized by a spontaneous, reversible polarization andpolar surfaces, which exhibit surface bound charges. Polar oxides with internal dipolarfields are able to internally separate photogenerated carriers via the bulk photovoltaiceffect. The unique properties of ferroelectric surfaces have been used to achievephotochemical oxidation or reduction reactions, including water splitting and surfacedecoration by metallic nanoparticles through ion reduction from the corresponding aqueoussalt solution. In addition, widespread concerns were focused on semiconductors decoratedwith noble metals due to the special structure of contact interface and electron transferproperties.Pb(ZrxTi1-x)O3(PZT) films with different Zr ratios were made by Sol-Gel method. Wefound that Ag nanoparticles are observed on the as-grown polycrystalline PZT filmswithout poling, because of the Scottky barrier on the PZT/ITO interface. With theincreasing of the Zr ratio, the resistivity and the bandgap of the PZT films are getting larger,leading to the larger density but less particle size of Ag clusters. When the concentrationreaches52%, the photogenerated electrons can not reach on the surface of the film toreduce the Ag+because of the high impedance state of film.In order to further study the effect of the different decorated noble nanopaticles on thephotoelectrochemical properties of PZT films, we photoreduced Ag, Au and Ptnanoparticles on the surface of PbTiO3films. We found that Ag and Au nanoparticles canharvest visible light, and a favorable energy level for the photoelectrochemical reactionwas formed between Ag and PbTiO3. It makes that Ag nanoparticles improve the PECproperties of PbTiO3photocathode most significantly among the three noble metal nanoparticles. The Pt nanoparticles weaken the PEC properties of PbTiO3photocathode asit can not harvest the visible light, and it has unfavorable energy level comparing with thePbTiO3. |
PDF Full Text Request