Sol—gel preparation and photoelectrochemical properties of TiO2 films containing Au and Ag metal particles (original) (raw)
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Deposition of TiO2 and Au: TiO2 film and their Photoelectrochemical Properties
ES Materials & Manufacturing, 2020
Gold (Au) nanoparticles were prepared by the electrochemical deposition of aqueous solution of auric chloride (AuCl 4) on the titanium dioxide (TiO 2) film. Before and after the electrochemical deposition, the TiO 2 film was soaked into dye solution of Rose Bengal. It is found that the photoelectrochemical properties were enhanced after the incorporation of Au nanoparticles along the TiO 2 film. Generally, the “hot electrons” were the main feature behind such properties and the hot electrons were the results of the incorporation of Au nanoparticles on the TiO 2 film that triggered the exothermic chemical process. Here dye molecules acted as a light absorber, where they converted the incoming photons from the sun rays into electron-hole pairs. The electron-hole pairs within TiO 2 showed the localized surface plasmon resonance (LSPR). In this process, the collective oscillations of free electrons confined at the metal surface (conductive substrates) were induced when the incoming incident frequency matched with collective oscillations of these free electrons and transferred them to the conduction band of semiconductor. This caused the enhancement of power conversion, ie, photovoltage and photocurrent.
Journal of the Ceramic Society of Japan, 1996
Effects of gold nanoparticle incorporation on the photoanodic properties were studied for fluorescein-, rose bengal-and nile blue A-deposited TiO2 film electrodes prepared by the sol-gel method. The incor poration of gold particles decreased the dye-induced photoresponse in the visible region, which was ascribed to the retarded electron transport in the conduction band due to the Schottky barriers at tita nia/gold interfaces. The extent of decrease in photoresponse, however, was the smallest for the elec trode sample with rose bengal, whose optical absorption well overlapped the surface plasma resonance of the gold particles. The dipole-dipole coupling between rose bengal molecules and gold particles was thought to enhance the photochemical processes, resulting in smaller reduction in the photoresponse.
Likius S. Daniel • Hiroki Nagai • Mitsunobu Sato, 2013
"Abstract To study the absorption spectra and photocurrent densities of metallic Ag nanoparticle/titania (Ag NP)/ TiO2 composite thin films, COMP-Agn, with various amounts of Ag (10 mol% Bn B80 mol%) were fabricated on a quartz glass substrate at 600 C using the molecular precursor method. Respective precursor solutions for Agnanoparticles and titania were prepared from Ag salt and a titanium complex. Apart from a surface plasmon resonance (SPR) peak around 400 nm, additional wide-range absorption spread in the wide vis-region at wavelengths greater than 400 nm was observed in the composite thin films. The wide-range absorption is due to a tip–tip plasmon mode, intraparticle plasmonic coupling of tip and cavity resonances (LSPR). The absorption spectral patterns could be categorized into three types, depending on the Ag NP content. The photocurrent density of the TiO2 thin film and COMP-Agn was measured under natural potential by a conventional three-electrode method using a Ag plate as a counter electrode. The photocurrent densities of COMPAgn were comparable to those of the three patterns categorized according to their absorption spectra. The cathodic photocurrent densities generated by COMP-Agn with Ag content greater than 45 mol% could be observed under both UV- and visible (vis-) light irradiation. The enhanced photocurrent density was observed till the Ag content was increased up to 70 mol%. Under dark conditions, cathodic current densities were 1/5–1/20 of those under vis-light irradiation probable due to chemical redox reactions that may occur to the system. On the basis of photoexcited electron transfer from Ag NPs to the TiO2 conduction band and the electrical conductivity of COMP-Agn, the excellent response to vis-light and major factors affecting the photoresponse and photocurrent polarity were clarified by LSPR."
Photoelectrochemical Analysis of Anion-Doped TiO[sub 2] Colloidal and Powder Thin-Film Electrodes
Journal of The Electrochemical Society, 2006
The photoelectrochemical characteristics of anion-doped TiO 2 powder and colloidal electrodes were investigated under UV and visible illumination. The solar absorption of TiO 2 was improved by synthesizing reduced forms of TiO 2 using anions of the main group elements ͑C, N, and P͒ to substitute for oxygen in the titania lattice. Analytical methods, including scanning electron microscopy, X-ray diffraction, elemental analysis, Raman, and UV-visible spectroscopy were employed to characterize these materials. The photoactivity of the electrodes was evaluated using a three-electrode configuration quartz photoelectrochemical cell using simulated solar irradiance. All anion-doped TiO 2 electrodes investigated, specifically C-, N-, and P-doped, increased the visible absorption ͑ Ͼ 400 nm͒ of n-TiO 2 , leading to higher photoactivity under solar light. The addition of methanol to the electrolyte reduced the rapid charge recombination and hence enhanced the photocurrents. Although the efficiency is not yet comparable to single-crystal n-TiO 2 , optimization of the parameters studied here showed that significant increases in photoactivity could be achieved over the native TiO 2 powder.
Photo-electrochemical properties of oxide semiconductors on porous titanium metal electrodes
Solar Energy Materials and Solar Cells, 2006
For the purpose of producing hydrogen using solar energy, we investigated the potential of porous titanium metal sheet (PTMS) with high surface area for use as the basal plates for various types of oxide semiconductor photo-electrodes. The TiO 2 photoelectrodes were prepared by oxidation of PTMS and flat titanium metal sheet (FTMS). The photocurrents of the TiO 2 /PTMS electrodes were always higher than TiO 2 /FTMS under the same oxidation conditions. The reflectance of PTMS was lower than FTMS over the entire wavelength spectrum, suggesting that the scattered light was absorbed more effectively on the former. A nanocrystalline WO 3 layer-loaded PTMS electrode (WO 3 /PTMS) showed a high photocurrent compared to WO 3 /FTMS, suggesting that PTMS is highly suitable as basal plates for semiconductor photoelectrodes. r
Nanocermet TiO 2 :Au thin film electrodes for wet electrochemical solar cells
TiO 2 :Au nanocermets and TiO 2 thin films covered with gold precipitates were obtained from RF reactive sputtering of mosaic Au:Ti or metallic Au targets. The influence of gold content, deposition temperature and post-deposition annealing on photoanodic behaviour and the structure of the obtained materials was examined by optical, structural and electrochemical measurements.
Photoelectrochemical properties of sol-gel obtained titanium oxide
Journal of The Serbian Chemical Society, 2008
The photoelectrochemical properties of a sol-gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350 °C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO 2 electrode upon illumination by UV light in H 2 SO 4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions.
Photoelectric properties and photocatalytic activity of silver-coated titanium dioxides
Dyes and Pigments, 2007
Silver was deposited onto the surface of different commercial titanium dioxides namely, the pigment ''K1001'' and the two photocatalysts ''P-25'' and ''Hombikat-UV''. Both the coated and the untreated materials were used as catalysts for the heterogeneous photocatalytic initiation of the photopolymerisation of an ethoxylated trisacrylate. The coated pigment ''K1001-Ag'' more effectively initiated acrylate polymerisation than the untreated material exhibiting only small photocatalytic activity. In contrast, the deposition of silver on the photocatalysts affected their photocatalytic activity detrimentally; in the presence of ''P-25-Ag'' after 120 s illumination, only 10% of the monomer was polymerised. In the presence of ''Hombikat-UV-Ag'' no photopolymerisation was observed.