Corrosion light absorption

Although the most commonly used redox couple to act as a hole transport medium is the I3 /I this does not mean the couple is necessarily unique. Actually the space for improvement for DSSCs that use this redox mediator is mostly limited to improvements in better light harvesting dyes [41]. Corrosion, light absorption and diffusion limitations had been identified for the l3 /I pair and it has been replaced successfully by cobalt-based redox systems [14], as well as by organic hole conductors [42]. Difficulties in sealing to prevent evaporation and water diffusion into the cell led to research into the substitution of liquid redox pair electrolyte, replacing the liquid for solid or quasi-solid hole-conduction media, such as polymeric, gel [43], or solid electrolytes [44]. 

Thietane is a superior inhibitor of corrosion of iron in 10% hydrochloric acid and its effectiveness is said to be due to partial polymerization on the surface of the iron. Addition of chloride ion reduces the inhibition, possibly by inducing ringopening with the formation of sulfhydryl groups. The cyclic sulfide also has been considered as an odorant for natural gas and its absorption by organic soil and clay have been determined. Stabilization of methylchloroform and trichloroethylene by thietane, 2-methylthietane, 3-hydroxythietane, and two spirothietane derivatives has been claimed. Phosphorus and tin derivatives of 3,3-bis-hydroxy-methylthie-tane are reported to be light stabilizers for poly(vinyl chloride), and the dibutyl-tin derivative is a catalyst for the polymerization of aliphatic isocyanates. Mercury and zinc compounds derived from phenylmercury or phenylzinc hydroxide and 3-... 

Since protection of electrodes against corrosion in the photoelectrolysis cells is a question of vital importance, many attempts have been made to use protective films of different nature (metals, conductive polymers, or stable semiconductors, eg., oxides). Of these, semiconductive films are less effective since they often cause deterioration in the characteristics of the electrode to be protected (laying aside heterojunction photoelectrodes specially formed with semiconducting layers of different nature [42]). When metals are used as continuous protecting film (and not catalytical "islands" discussed above), a Schottky barrier is formed at the metal/semiconductor interface. The other interface, i.e., metal/electrolyte solution is as if connected in series to the former and is feeded with photocurrent produced in the Schottky diode upon illuminating the semiconductor (through the metal film). So, the structure under discussion is but a combination of the "solar cell" and "electrolyzer" within the photoelectrode Unfortunately, light is partly lost due to absorption by the metal film. 

Phenylhydrazine (CAS 100-63-0) A strong base and corrosive upon direct contact. A potent skin sensitizer. Dermal absorption occurs. Vapors very irritating to eyes and respiratory tract. May cause hemolytic anemia with secondary kidney damage. Limited evidence of carcinogenicity in test animals. 0.1 ppm, S,A3 NIOSH CA 15 ppm 3 2 0 Pale yellow crystals or oily liquid with a weakly aromatic odor. Darkens upon exposure to air and light. Vapor pressure is less than 0.1 mm Hg at 20°C (68°F). Combustible. Thermal-breakdown products include oxides of nitrogen. 

In the case of metallic adsorbates (metal deposits, underpotentially deposited upd-layers, catalytically active metal deposits), the type of coordination to surface sites (one-, two- or three-fold) and the distance to these sites may be of interest. Vice versa the same type of data may be of importance in the case of adsorbed ions on metal electrodes or about the atomic environment of a given atom/ion in an interphase. Analysis of the fine structure of X-ray absorption (EXAFS, XANES) close to the X-ray absorption edge of the species (atom) of interest will yield this data provided the sample can be prepared in a very thin layer in order to exclude unwanted bulk interference. Otherwise the experiment can be done in reflection (SEXAFS). Information about the distance between the atom of interest and its first and sometimes even second shell of surrounding species can be derived from the spectra [95]. Availability of a suitable light source, generally a synchrotron (for details see p. 15), is an experimental prerequisite. The method has been applied in studies of passive and corrosion layers on various metals [96-102] and of molecular and ionic adsorbates on single crystal surfaces [103]. 

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