Fast interfacial electron transfer

Refs. [i] Bard AJ, FaulknerLR (2001) Electrochemical methods, 2nd edn. Wiley, New York, pp 487-516 [ii] Amatore C, Maisonhaute E (2005) Anal Chem 77-.303A [iii] FeldbergSW, Newton MD, Smalley JF (2003) The indirect laser-induced temperature jump method for characterizing fast interfacial electron transfer concept, application, and results. In Bard AJ, Rubinstein I (eds) Electroanalytical chemistry, vol. 22. Marcel Dekker, New York, pp 101-180... 

Armstrong, F. A., and Lannon, A. M., 1987, Fast interfacial electron-transfer between cytochrome-c peroxidase and graphite-electrodes promoted by aminoglycosides-novel electroenzymic catalysis of HjOj reduction, J. Am. Chem. Soc. 109 7211n7212. 

LuH., Prieskom J. N. and Hupp J. T. (1993), Fast interfacial electron transfer evidence for inverted region kinetic behavior , J. Am. Chem. Soc. 115, 4927 928. 

THE INDIRECT LASER-INDUCED TEMPERATURE-JUMP METHOD FOR CHARACTERIZING FAST INTERFACIAL ELECTRON TRANSFER CONCEPT, APPLICATION, AND RESULTS... 

A. Why Measure Fast Interfacial Electron Transfer Rate Constants And How 103... 

II. THE EVOLUTION OF THE ILIT METHOD FOR THE STUDY OF FAST INTERFACIAL ELECTRON TRANSFER KINETICS... 

The response times of neat SAMs in the absence of a redox moiety Our theoretical analysis for the ILIT response has presumed that dC /dt is infinitely fast—if that is not the case, extracting meaningful values of will be difficult, if not impossible. We have already mentioned evidence of a slow response of SAMs formed from 11-mercaptoundecanoic acid [113] (Sec. VII). We expect that the results of these types of experiments will be critically dependent upon the choice of the SAM constituent, the SAM preparation, substrate metal, temperature, the solvent, and the electrolyte ions (the less hydrophobic, the better). A thorough study of the potential of zero response would be important and informative. Establishing which films exhibit the fast responses will be critical for any meaningful studies of fast interfacial electron-transfer kinetics. 

The Indirect Laser-Induced Temperature Jump Method for Characterizing Fast Interfacial Electron Transfer Concept, Application, and Resnlts,... 

There is no doubt that this field, like few others, owes very much to its founder, Ronald Gurney, because of the fast start he gave it by applying quantum mechanics to interfacial electron transfers shortly after the publication of Schrodinger s wave equation (1926). The early seminal contributions (to which must be added that of J. A. V. Butler in the same period)22 founded quantum electrochemistry and led to its broader development by Gcrischer (1960), in particular the idea of the absolute scale of potentials and the equation... 

The long effective pathlength and high surface area afforded by these colloidal semiconductor materials allow spectroscopic characterization of interfacial electron transfer in molecular detail that was not previously possible. It is likely that within the next decade photoinduced interfacial electron transfer will be understood in the same detail now found only in homogeneous fluid solution. In many cases the sensitization mechanisms and theory developed for planar electrodes" are not applicable to the sensitized nanocrystalline films. Therefore, new models are necessary to describe the fascinating optical and electronic behavior of these materials. One such behavior is the recent identification of ultra-fast hot injection from molecular excited states. Furthermore, with these sensitized electrodes it is possible to probe ultra-fast processes using simple steady-state photocurrent action spectrum. 

In this section, we will treat the one-step, one-electron reaction O + R using the general (quasireversible) i-E characteristic. In contrast with the reversible cases just examined, the interfacial electron-transfer kinetics in the systems considered here are not so fast as to be transparent. Thus kinetic parameters such as kf, and a influence the responses to potential steps and, as a consequence, can often be evaluated from those responses. The focus in this section is on ways to determine such kinetic information from step experiments, including sampled-current voltammetry. As in the treatment of reversible cases, the discussion will be developed first for early transients, then it will be redeveloped for the steady-state. 

As mentioned above, both electrons and holes must be efficiently separated and both must reach the particle surface. Even when both reach the surface, recombination may still predominate if both are not consumed in appropriate fast reactions. It is worth reiterating that the requirements for fast reactions are twofold. The first is favorable energetics. The redox couples must be included within the band gap as shown in FIGURE 2. But, it is also necessary to maximize the rate of interfacial electron transfer.- This is essentially a standard problem of electrochemical kinetics and, as such, one for which there are extensive precedents. Above, we mentioned the general theoretical rules. Here, we will give more attention to specific examples. In most cases, experimental results can provide precedents. 

We assume that C , Ep, and Ftj respond instantaneously to the change in interfacial temperature. It is only ctm that might not respond instantaneously. For a reversible (i.e., infinitely fast) one-electron transfer, we can write... 

As noted in the introduction, the development of viable WOCs is central to the ultimate realization of useful devices for generating green fuel (solar fuels and others) [21, 22, 32, 58, 59]. Viable means fast, selective and extremely stable but also compatible with the other unit operations (light collection, exciton generation, and interfacial electron transfer) [60]. Given the central importance of WOCs, there... 

Spectroelectrochemical methods have been used in recent years to study fast-photoinduced electron transfer at the liquid/liquid interface.- "- - Of particular importance is extending the idea of employing solvent (typically N,N-dimethylaniline or DMA) as an electron donor to the liquid/liquid interface.The advantage of this approach is that complications due to ion transfer across the interface and to diffusion are obviated. Several studies of ET between coumarin dyes and electron-donating solvents in micelles, reverse micelles, at the surface of proteins, and in nanocavities have demonstrated ultrafast electron transfer that is faster than solvation due to the close proximity of the redox pair. These experiments provided additional evidence for the existence of the Marcus-inverted region at liquid interfacial sy stems. ... 

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