Interaction molecule-electrode

The interactions between electrode metals and solvents are reflected in the adsorption and catalytic properties. The adsorption of other solution components (ions and neutral molecules other than the solvent) is attended by a displacement of adsorbed solvent molecules or their reorientation. Therefore, a metal s adsorptive power is low under conditions where its energy of interaction with the solvent is high. 

Correspondingly, the forces involved in the adsorption of organic molecules can be classified into three categories organic molecule-electrode forces, water-electrode forces, and lateral interactions. These forces are the same as those we studied in the adsorption of ions on electrodes, and their nature was described in Section 6.8.2. 

When natural or synthetic DNA molecules interact with electrode surfaces adsorption occurs. The knowledge about the adsorption of nucleic acids onto the electrode surface leads to the development of DNA-modified electrodes, also called electrochemical DNA biosensors [3-6,19-24], An electrochemical DNA biosensor is an integrated receptor-transducer device that uses DNA as the biomolecular recognition element to measure specific binding processes with DNA, using electrochemical transduction. 

Computer simulations of metal/electrolyte interfaces are a great challenge. Explicit water molecules bring new degrees of freedom for atoms and electrons, and accurate and physically realistic simnlations require solvent dynamics. Taylor and Neurock reviewed recent work on metal/water interfaces focusing on water stracture and other interactions with electrode surfaces. ... 

Implementation of this method to different structures shows that it can provide a qualitative description of quantum transport in nanostructures, but the jellium model of electrodes oversimplifies the molecule-electrode interaction which plays an important role in quantative theory. 

Apart from small molecules, insights into the adsorption of biomacromolecules are very important for understanding their role in many biological processes. The adsorption of such molecules is considerably more complex than that of small ones, and adsorptive stripping voltammetry has been very useful for obtaining new knowledge of their interaction with electrodes 22,24,... 

The electrical double layer at Hg, Tl(Ga), In(Ga), and Ga/aliphatic alcohol (MeOH, EtOH) interfaces has been studied by impedance and streaming electrode methods.360,361 In both solvents the value ofis, was independent of cei (0.01 < cucio4 <0.25 M)and v. The Parsons-Zobel plots were linear, with /pz very close to unity. The differential capacity at metal nature, but at a = 0,C,-rises in the order Tl(Ga) < In(Ga) < Ga. Thus, as for other solvents,120 343 the interaction energy of MeOH and EtOH molecules with the surface increases in the given order of metals. The distance of closest approach of solvent molecules and other fundamental characteristics of Ga, In(Ga), Tl(Ga)/MeOH interfaces have been obtained by Emets etal.m... 

Good agreement between C(- and the dipole moment of the solvent (H20) molecules (i.e., by the hydrophilicity of metals) established by Trasatti25,31 was found and the reasons for this phenomenon were explained 428 The Valette and Hamelin data150 251 387-391 are in agreement with the data from quantum-chemical calculations of water adsorption at metal clusters 436-439 where for fee metals it was found that the electrode-H20 interaction increases as the interfacial density of atoms decreases. 

As discussed in Section I.3(i), AX indicates the variation in the work function of a metal as an interface is created by bringing a solid and a liquid in contact. In principle, it should be possible to compare AX values with A values measured directly in gas phase experiments. This is the aim of UHV synthesis of the electrochemical double layer868 in which the electrode interface is created molecule by molecule, starting with the bare metal surface. It is thus possible to obtain evidence of ion-water interactions that can be envisaged from electrochemical measurements but that are not directly demonstrable. Wagner55 has given a recent comprehensive review of electrochemical UHV experiments. 

We first assume Langmuir-type adsorption (E=0 or P,=0) which implies negligible lateral interactions between adsorbed molecules and negligible inherent or induced heterogeneity of the catalyst-electrode surface ... 

The strength of the adsorptive interaction as expressed in values of AG jj depends on the mode of interaction between the adsorbate molecule and the electrode surface. Weak adsorption (physisorption) is based mostly on van-der-Waals-interactions. It shows t5q)ically values of AG jj > - 20 kJ mol Stronger... 

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