The subject of sol-gel electrochemistry is introduced, starting with a brief account of milestones in its evolution. Then, the types of sol-gel materials that are useful for electrochemistry are presented, followed by a description of recent advances in the various fields of sol-gel electrochemistry. Modified electrodes, solid electrolytes, electrochromic devices, and corrosion protection coatings are described. Emerging fields such as RuO 2 supercapacitors and electrochemical synthesis of sol-gel precursors are also addressed.
Electronic transport in gold−dithiol nanoparticle films was studied using conductivity, photoconductivity,
and photoelectrochemical means. The films were characterized by SEM and optical spectroscopy. GC/MS
was used for the analysis of the pyrolysis products during heat treatment. Films were assembled on glass
substrates using gold sol and different alkanethiol spacers (1,2-ethanedithiol (C2), 1,5-pentanedithiol
(C5), and 1,8-octanedithiol (C8)). Resistance−temperature measurements revealed that the effective
activation energies for conduction were 0, 5, and 15 meV for films assembled using C2, C5, and C8 spacers,
respectively. Light action spectra of photoconductivity of gold−dithiol nanoparticle films revealed 0.8−1.0
eV threshold photon energy. The difference between the observed threshold energies points to different
mechanisms for conductivity and photoconductivity. The low effective activation energy for dark conduction
is attributed to a mixed mechanism of conduction, tunneling between insulated particles, and metal
conduction through defects which are ascribed to direct contact points between metal particles. The
photoconductivity mechanism involves photoemission from metal particles into the insulator layer.
Photoelectrochemical studies of gold nanoparticle electrodes in aqueous electrolyte revealed 3.5 eV photon
energy threshold of the photocurrent at an electrode potential of E = 0 V vs Ag/AgCl reference. The much
higher photoelectrochemical threshold energies are ascribed to direct photoemission processes from the
surface metal particles into the electrolyte. Heat treatment of the films decreased film resistance and
increased the temperature coefficient of resistance to values approaching that of metal gold. These trends
are attributed to pyrolysis of spacer molecules, which favor the metal conduction mechanism.
We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.
The complex [Cp* 2 Mo 2 O 5 ] (Cp* = η 5 -C 5 Me 5 ) and its electrochemical reduction products in acetic acid/acetate-buffered (pH = 4.0) water/methanol solutions were investigated by combined electrochemical (EC) flowcell and on-line electrospray ionization mass spectrometry (ESI-MS). Mono-, di-, tri-, and tetranuclear organometallic molybdenum oxides were identified in the starting solution. The effect of the relevant ESI-MS parameters (ionic mode, heated capillary voltage, and heated capillary temperature) and of the concentration on the observed distribution of ions in the mass spectrometer was studied in order to minimize side reactions in the ESI chamber. It was verified that reduction in the ESI-MS is
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