Deposition of Metallic Oxides on TiO₂ Electrode Using the Photoelectrochemical Epitaxial Growth Technique (PEEG), and Electrochemical Behavior of the PbO₂/TiO₂ Electrode

Abstract

The deposition of metallic oxides onto both single crystal and polycrystalline TiO 2 electrodes using the photoelectrochemical technique was carried out, and the electrochemical behavior of the prepared PbO 2 /TiO 2 electrode was studied. The photoelectrodeposition of PbO 2 , Fe 2 O 3 and MnO 2 occurred under illumination but not in the dark. The crystal orientation of the deposited oxides strongly depended on the crystal misfit between the oxides and the TiO 2 substrate. Even pulse illumination brought about the deposition, because the OH radical produced on the surface by a hole significantly contributes to the oxide deposition during the initial step. The PEEG (photoelectrochemical epitaxial growth) model was proposed, and compared with the AFM images. From the measurements of the current-potential curve of the PbO 2 /TiO 2 electrode, it was found that the PbO 2 deposited on the polycrystalline TiO 2 produces a surface state leading to a large anode tunneling current and that Fermi level pinning occurs at the PbO 2 /TiO 2 interface. The present PbO 2 /polycrystalline TiO 2 electrode was very stable in acidic solution, and therefore, will be very useful as an inert anode.

Performance characterization of Ti substrate lead dioxide electrode with different solid solution interlayers

“…The known failure mechanisms of Ti/PbO 2 electrode include flaking off of the fragile PbO 2 coating to the electrolyte and generating TiO 2 insulating layer between the substrate and coating [1,6]. A lot of efforts have been made to improve the stability of the Ti/PbO 2 electrode.…”

Photochemical formation of semiconducting nanostructures

“…The nanocomposites TiO 2 /PbO 2 , TiO 2 /Fe 2 O 3 , and TiO 2 /MnO 2 were obtained in this way [113].…”

“…This is due to the ability of the nanoparticles of the metal to accept and accumulate electrons photogenerated in the semiconducting nanoparticles and to fulfill the role of their carrier onto the acceptor substrates [5,7,148] and, in some cases, also to the more effective adsorption of the phototransformation substrate on the metal nanoparticles compared with the semiconducting nanoparticles [135]. Thus, the TiO 2 /Pt 0 nanocomposites produced by photodeposition are more active than the individual TiO 2 nanoparticles in the photocatalytic reduction of water with the release of hydrogen [119-121, 132, 134, 137, 138, 142], the reduction of azobenzene [122], the oxidation of CO [135], toluene [131], phenol and its derivatives [113,136,143,167], carboxylic acids [113,119,120,125,141], methanol [133,134,156], acetone [127], acetaldehyde [114,128,140], dyes [130,168], polychloroethylenes [116], decomposition of ozone [123], and oxidation of thiocyanate anions [155]. The possibility of using such nanostructures for photocatalytic steam reforming of methane with the formation of H 2 and CO 2 was demonstrated in [139].…”

Site-selective deposition of binary Pt–Pb alloy nanoparticles on TiO2 nanorod for acetic acid oxidative decomposition

“…This reaction was carried out in an aqueous rutile TiO 2 nanorod suspension (1 g L À1 ) containing 1 M Pb(NO 3 ) 2 under an aerated condition. The pH of the solution for this reaction was adjusted to 1.0 by the addition of nitric acid according to the literature [20,23]. After photoreaction for 12 h using a 300 W Xe-lamp (Perkin Elmer, PE300BF) under full arc, the light intensity was 0.1 mW/cm 2 , and the color of the powder changed from white to brown, indicating that PbO 2 had been deposited on the surface.…”

“…To determine reactive sites on the exposed crystal faces of the prepared TiO 2 -rod, photodeposition of Pt and PbO 2 was carried out, which method is used to determine reactive sites for wellfaceted TiO 2 material [19][20][21]23]. The colors of the prepared TiO 2 powder after UV-light irradiation in the presence of H 2 PtCl 6 aqueous solutions changed to gray.…”