Electrode photosensitive

The general scheme of a QDSC device is similar to the DSC concept. Light excites electron-hole pairs in the QDs. The electrons are injected into nanostructured Ti02 electrode (photosensitization), and they are transported to the transparent conductive oxide electrode. The holes are injected into the liquid or solid electrolyte which acts as a hole-transporting medium. The resulting holes are transported to the counterelectrode, where the oxidized... 

An interesting idea has been to prepare the photosensitive electrode on site having the liquid play the dual role of a medium for anodic film growth on a metal electrode and a potential-determining redox electrolyte in the electrochemical solar cell. Such integration of the preparation process with PEC realization was demonstrated initially by Miller and Heller [86], who showed that photosensitive sulfide layers could be grown on bismuth and cadmium electrodes in solutions of sodium polysulfide and then used in situ as photoanodes driving the... 

Fujishima A, Sugiyama E, Honda K (1971) Photosensitized electrolytic oxidation of iodide ions on cadmium sulfide single crystal electrode. Bull Chem Soc Japan 44 304 Inoue T, Watanabe T, Fujishima A, Honda K, Kohayakawa K (1977) Suppression of surface dissolution of CdS photoanode by reducing agents. J Electrochem Soc 124 719-722 Elhs AB, Kaiser SW, Wrighton MS (1976) Visible light to electrical energy conversion. Stable cadmium sulfide and cadmium selenide photoelectrodes in aqueous electrolytes. J Am Chem Soc 98 1635-1637... 

Toyoda T, Kobayashi J, Shen Q (2008) Correlation between crystal growth and photosensitization of nanostructured HO2 electrodes using supporting H substrates by self-assembled CdSe quantum dots. Thin SoUd Films 516 2426-2431... 

Magnetic field effects on the photoelectrochemical reactions of photosensitive electrodes are very important for practical applications of the MFEs in controlling the photoelectronic functions of molecular devices. Previously, we have examined MFEs on the photoelectrochemical reactions of photosensitive electrodes modified with zinc-tetraphenylporphyrin-viologen linked compounds [27, 28] and semiconductor nanoparticles [29, 30[. However, MEEs on the photoelectrochemical reactions of photosensitive electrodes modified with nanoclusters have not yet been reported. 

Asa study of spin chemistry at solid/liquid interfaces, we have examined M F Es on the photoelectrochemical reactions of photosensitive electrodes modified with nanoclusters containing CgoN and MePH (Figure 15.4), intended for utilization of C o as photofunctional nanodevices. 

The use of non-inert and chemically modified electrodes and other strategies for the detection of species that are difficult to analyze with the normal electrode materials have been reviewed.55 Photosensitization prior to amperometric detection is another tactic that has proved useful for the analysis of substances that are normally considered to be electrochemically inert.56 The use of pulsed amperometry has recently been reviewed.57... 

In such devices the light-absorbing semiconductor electrode immersed in an electrolyte solution comprises a photosensitive interface where thermodynamically uphill redox processes can be driven with optical energy. Depending on the nature of the photoelectrode, either a reduction or an oxidation half-reaction can be light-driven with the counterelectrode being the site of the accompanying half-reaction. N-type semiconductors are photoanodes, p-type semiconductors are photocathodes, and... 

PMTs contain a photosensitive cathode and a collection anode that are separated by electrical electrodes called dynodes, which provide electron multiplication or gain. The cathode is biased negatively by 400-2500 V with respect to the anode. An incident photon ejected by the photocathode strikes the first dynode... 

Besides silicon, other materials have also been used in micro fuel cells. Cha et al. [79] made micro-FF channels on SU8 sheets—a photosensitive polymer that is flexible, easy to fabricate, thin, and cheaper than silicon wafers. On top of fhe flow channels, for both the anode and cathode, a paste of carbon black and PTFE is deposited in order to form the actual diffusion layers of the fuel cell. Mifrovski, Elliott, and Nuzzo [80] used a gas-permeable elastomer, such as poly(dimethylsiloxane) (PDMS), as a diffusion layer (with platinum electrodes embedded in it) for liquid-electrolyte-based micro-PEM fuel cells. 

Fujishima A, Sugiyama E, Honda K (1971) Photosensitized electrolytic oxidation of iodide ion on cadmium sulfide single crystal electrode. Bull Chem Soc Jpn 44 304... 

Schibler Has anyone used multi-unit electrode approaches to study the intrinsically photosensitive ganghon cells ... 

It has recently been shown by Spikes150 that uracil and a number of substituted uracils are subject to dye-sensitized photooxidation under certain conditions. Methylene blue and Eosin Y were active photosensitizers in the pH range 8-11.5, but were inactive below pH 8. FMN was very active over the pH range of 2.4-11.5. Photooxidation was measured with a rotating platinum oxygen electrode. 

Figure 17.50 J-V curves of Co(II)/(III)-mediated cell employing a gold (dashed line) and a PEDOT counter electrode (solid line). Electrolyte composition 0.15M Co(II)/0.5M Li+/ 0.1 M Tbpy in acetonitrile. Cell equipped with a 120 pm spacer. Photosensitizer Z907. From Bignozzi et al., unpublished results.

If a solution, being in contact with an electrode, contains photosensitive atoms or molecules, irradiation of such a system may lead to photoelectro-chemical reactions or, to be more exact, electrochemical reactions with excited particles involved. In such reactions the electrons pass either from an excited particle to the electrode (the anodic process) or from the electrode to an excited particle (the cathodic process). In this case, an elementary act of charge transfer has much in common with ordinary (dark) electrochemical redox reactions, which opens a possibility of interpreting certain aspects of photochemical processes under consideration with the use of concepts developed for general quantum mechanical description of electrode processes. 

Photosensitive substances adsorbed on the semiconductor surface are especially efficient in sensitization reactions. Thus, sensitizing effect can be enhanced if a sensitizer is attached to the semiconductor surface by a chemical bond. For this purpose one has to create either the ether bond -O-between the semiconductor and reactant, using natural OH groups, which exist on the surface of, for example, oxide semiconductors (Ti02, ZnO) or oxidized materials (Ge, GaAs, etc.) in aqueous solutions, or the amide bond -NH- in the latter case a monolayer of silane compounds with amido-groups is preliminarily deposited on the semiconductor surface (see, for instance, Osa and Fujihira, 1976). With such chemically modified electrodes the photocurrent is much higher than with ordinary (naked) semiconductor electrodes. 

Fig. 26. Dependence of photosensitized current (arb. units) on solution pH at Ti02 (1) and CdS (2) electrodes sensitized by Rhodamin B. [From Watanabe et al. (1976).]...

In the other scheme the photosensitive interface operates in the photo-galvanic pair regime (Goryachev et al, 1970 Goryachev and Paritsky, 1973). The method is based on the occurrence of a potential difference between illuminated and nonilluminated areas on the surface of a semiconductor electrode in a solution (cf. Section 1 lb). As a result of nonuniform illumination, local anodes and cathodes arise on the surface and this, in turn, leads to nonuniform deposition of metal onto the surface. 

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