Fermi level of metal

Equation (7.32) underlines the pinning of the Fermi levels of metal electrodes with the solid electrolyte and reminds the fact that the absolute electrode potential is a property of the solid electrolyte and of the gaseous composition but not of the electrode material.21... 

We then take the electron in the vacuum to a point just above metal II this requires the work —eoO/ n — V i)- We then take the electron to the Fermi level of metal II, and gain the energy — n- Since the total work for this process must be zero, we obtain ... 

Figures 8-5 and 8-6 are energy diagrams, as functions of electron energy e imder anodic and cathodic polarization, respectively, for the electron state density Dyf.t) in the metal electrode the electron state density AtEDox(c) in the redox particles and the differential reaction current ((e). From these figures it is revealed that most of the reaction current of redox electron transfer occurs in a narrow range of energy centered at the Fermi level of metal electrode even in the state of polarization. Further, polarization of the electrode potential causes the ratio to change between the occupied electron state density Dazc/itnu md the imoccupied...

It is characteristic of metal electrodes that the reaction current of redox electron transfer, under the anodic and cathodic polarization conditions, occurs mostly at the Fermi level of metal electrodes rather than at the Fermi level of redox particles. In contrast to metal electrodes, as is discussed in Sec. 8.2, semiconductor electrodes exhibit no electron transfer current at the Fermi level of the electrodes. 

Figure 5 An energy diagram of a semicondnctor/metal jimction in acciunulation. (a) Before charge eqndibration occurs, the electrochemical potential of the semiconductor (Fp.sc) is more positive than the Fermi level of metal (i/p.m), and electrons will flow from the metal into the semiconductor, (h) After charge equihhration has occurred, an acciunulation layer containing negative charges is formed in the semiconductor...

FIGURE 22.38 Electronic energy diagrams for a metal electrode in contact with a p-type semiconducting metal oxide (a) prior to contact, (b) posterior to contact, and (c) with photoexcitation neF = quasi-Fermi level for photoexcited electrons in oxide, eM = Fermi level of metal dissolution reaction, and eHY = Fermi level of hydrogen reaction. 

Fig. 6.1. Representation of four possible idealized potential barriers between two metal electrodes for electron vacuum tunneling using a trapezoidal barrier, (a) Two non-interacting electrodes separated by a vacuum. The difference in Fermi levels, E, is equal to the difference in work functions, (j), of the two materials, (b) The potential barrier after the electrodes are brought within tunneling distance and allowed to come to equilibrium at a common Fermi level. The variation in field within the vacuum space is due to the difference in work function, (c) and (d) Barrier after a voltage, elf is applied between the electrodes raising the Fermi level of metal 1 relative to metal 2 and vice versa, respectively.

Fig. 6.3. Semiconductor representation for (a) NIN, (b) NIS, and (c) SIS tunnel junctions showing the DOS vs. energy. The expected current/voltage characteristic for each type of junction is included on the right hand side. In each case the Fermi level of metal 1 is raised by e F with respect to metal 2. The dashed lines indicate the characteristics at T>0, and the solid lines indicate the current for T — 0.

How is this equilibration of the Fermi levels of metal and redox couple achieved Consider a platinum electrode that is not connected to a power supply and an aqueous solution containing the electron acceptor A in Figure 11 at a concentration of 1 mM and 0.4 pM of its singly reduced... 

Figure 5. Fowler plots of the photocurrent data for (1) anodic photocurrent and (2) cathodic photocurrent of the PANIfilm on ordered Au/p-ATP substrate in 0.05MK3Fe(CN)e/K4Fe(CN)e aqueous solution. Extrapolated photocurrent onsets indimte the energy barrier difference between the Fermi level of metallic region and the conduction band (cathodic photocurrent) or the valence band (anodic photocurrent) of semiconducting region in PANI film.

In EC-SERS systems, both chemical and electromagnetic enhancements can be influenced to some extent by changing the applied electrode potential - that is, the Fermi level of metal and dielectric constant of the interfacial electrolyte. The former in particular can be strongly tuned by potential, leading to drastic changes in interfacial structure and properties. Such properties have led to EC-SERS being one of the most complicated systems in SERS the features of EC-SERS will be briefly introduced at this point. 

Fig. 7.5 Energy of the redox couples of iron (left) and vanadium (right) phosphate frameworks relative to the Fermi level of metallic lithium...

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