Electrode interfacial design

Chen D, Li J. Interfacial design and functionization on metal electrodes through self-assembled monolayers. Surface Science Reports 2006, 61, 445 163. 

Our research builds on this limited body of work concerning diffusion at the interface of adhesive joints. We have measured the interfacial diffusion process of acetone into a bonded pressure sensitive adhesive tape bj employing single frequency capacitance measurements and a novel interdigitated electrode sensor design. 

The absorption of acetone at room temperature into an adhered PSA tape was measured by applying the technique of SFCM and utilizing a unique interdigitated electrode sensor design. The interfacial diffusion results and adhesion measurements were compared, and the relationship between the relative concentration and adhesion loss was determined. This study suggests these novel sensors are applicable for the study of interfacial diffusion processes, and could be extended to other coatings or adhesives in a variety of environments. 

Yoshihara S, Katsuta H, Isozumi H et al (2011) Designing current collector/composite electrode interfacial structure of organic radical battery. J Power Sources 196(18) 7806-7811... 

Although there are only three principal sources for the analytical signal—potential, current, and charge—a wide variety of experimental designs are possible too many, in fact, to cover adequately in an introductory textbook. The simplest division is between bulk methods, which measure properties of the whole solution, and interfacial methods, in which the signal is a function of phenomena occurring at the interface between an electrode and the solution in contact with the electrode. The measurement of a solution s conductivity, which is proportional to the total concentration of dissolved ions, is one example of a bulk electrochemical method. A determination of pH using a pH electrode is one example of an interfacial electrochemical method. Only interfacial electrochemical methods receive further consideration in this text. 

Empirical kinetics are useful if they allow us to develop chemical models of interfacial reactions from which we can design experimental conditions of synthesis to obtain thick films of conducting polymers having properties tailored for specific applications. Even when those properties are electrochemical, the coated electrode has to be extracted from the solution of synthesis, rinsed, and then immersed in a new solution in which the electrochemical properties are studied. So only the polymer attached to the electrode after it is rinsed is useful for applications. Only this polymer has to be considered as the final product of the electrochemical reaction of synthesis from the point of view of polymeric applications. 

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. 

A modification of the RDC design, based on the ring-disk arrangement of the RDE [36], incorporated an arc electrode [37,38] deposited on the surface of the membrane around the untreated area. This facilitated the electrochemical detection of species reacting at the interface at short times following the reaction. This method was used to study the solvent extraction of cupric ions, which were detected by reduction to copper metal at the arc electrode. The resulting current flow was related to the interfacial flux at the membrane. 

The work reported here was designed to address the issue of adsorbate surface coverage in the effect on SERS of UPD Pb on Ag electrodes in aqueous chloride and bromide media using interfacial H20 species as the probe molecule. No studies have been reported on the effect of UPD layers on the SERS of interfacial solvent molecules previously. However, the solvent is an ideal choice for such studies, because it will always remain in intimate contact with the electrode surface. Moreover, the SERS of interfacial H20 has been characterized quite extensively in aqueous halide media (18-29) and allows the possible influence of anion on the response of the system to be assessed. 

In UHV surface spectroscopies, the electrode under investigation is bombarded by electrons, photons, or ions, and an analysis of the electrons, ions, molecules, or atoms scattered or released from the surface provides information related to the electronic and structural parameters of the atoms and ions in the interfacial region. As mentioned before, the transfer of the electrode from the electrochemical cell to the UHV chamber is a crucial step in the use of these techniques. This has motivated a few groups to build specially designed transfer systems. Pioneering work in this area was done by Hubbard s group, followed by Yeager. 

However, there is another kind of influence on current distribution that may even the score. This is called secondary current distribution and describes the resistances set up at the interface of the working electrodes in a cell in which the interface tends to be polarizable. For example, it was shown [Eq. (7.36)] that when f) < RT/F, the interfacial resistance per unit area is RT/igF. If i0 is very small (e.g., 10-10 A cm-2, hence, an interfacial resistance cm-2 of 2.6 x 10 ohms), it is this interfacial resistance and not the ohmic resistance in the bulk solution that detennines the current distribution. Thus, in an extreme case of high solution concentration (low solution resistance) and low i q, a substantial fraction of the length of the pores in a porous electrode remains active.34 Considerations such as these, together with resistance effects at edges, all count in cell design. 

In section B-C, the fraction of the current used to charge the interfacial region to the designated overpotential is progressively reduced and more and more of the current flowing between electrode and solution is due to electrons that cross the interfacial region and take part in the electrochemical reaction. By C, all the electrons (for i, at T),) are being used in the electrode reaction which then, from a simplistic point of view, should continue to flow at a constant rate independent of time. 

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