Electrified solid-liquid interface

In recent years, advances in experimental capabilities have fueled a great deal of activity in the study of the electrified solid-liquid interface. This has been the subject of a recent workshop and review article [145] discussing structural characterization, interfacial dynamics and electrode materials. The field of surface chemistry has also received significant attention due to many surface-sensitive means to interrogate the molecular processes occurring at the electrode surface. Reviews by Hubbard [146, 147] and others [148] detail the progress. In this and the following section, we present only a brief summary of selected aspects of this field. 

One of the most important advances in electrochemistry in the last decade was tlie application of STM and AFM to structural problems at the electrified solid/liquid interface [108. 109]. Sonnenfield and Hansma [110] were the first to use STM to study a surface innnersed in a liquid, thus extending STM beyond the gas/solid interfaces without a significant loss in resolution. In situ local-probe investigations at solid/liquid interfaces can be perfomied under electrochemical conditions if both phases are electronic and ionic conducting and this... 

The latter report demonstrated the unique ability of this technique to resolve surface structure as well as surface composition at the electrified solid-liquid interfaces. In particular, STM has become an important tool for ex situ and in situ characterization of surfaces at the atomic level, in spite its significant limitations regarding surface composition characterization for bimetallic systems, such as the lack of contrast for different elements and the scanned surface area being too small to be representative for the entire surface. To avoid these limitations, STM has been mostly used as a complementary tool in surface characterization. 

Overall, this chapter aimed to emphasize and demonstrate the great potential of utilizing a multidisciplinary approach to bimetallic systems that combines computational methods with a number of highly sophisticated in situ and ex situ surface-sensitive techniques at electrified solid-liquid interfaces. Advances in the understanding of fundamental properties that govern catalytic processes at well-defined multimetallic... 

In the following we will focus on three molecular electronics test beds as developed and employed for applications at electrified solid/liquid interfaces (1) STM and STS, (2) assemblies based on horizontal nanogap electrodes, and (3) mechanically-controlled break junction experiments. For a more detailed description of the methods we refer to several excellent reviews published recently [16-22]. We will also address specific aspects of electrolyte gating and of data analysis. 

Tao et al. [32] pioneered a technique based on the formation of single molecular junctions between the tip of an STM and a metal substrate. The method was adapted by other groups, modified and applied to a large number of molecular conductance studies at (electrified) solid/liquid interfaces [33, 113-119]. For details we refer to Sect. 2.3. 

STM and AFM Studies of the Electrified Solid-Liquid Interface Monolayers, Multilayers, and Organic Transformations... 

Charge Transport in Single Au/Molecule/Au Junctions at Electrified Solid-Liquid Interfaces... 

The response of an electrified solid-liquid interface to shearing stress applied tp or induced in a contiguous liquid phase is termed an electro-kinetic phenomenon. The fundamental physical assumptions on which the molecular interpretation of electrokmetic phenomena is based are that an... 

In-situ vibrational spectroscopy has long been used to study the electrified solid/ liquid interface. By using the information given by peak position, width, and lifetime, vibrational spectroscopy can provide the chemical identity of the adsorbate, an estimation of surface coverage, and the orientation and even dynamics of molecules at the electrode. Three different types of vibrational spectroscopy are relevant to the solid/liquid interface. The first two of these, Raman and infrared spectroscopy, are thoroughly discussed in this book. A third technique successfully used to probe the Uquid/soUd electrochemical interface is vibrational sum frequency generation (SFG). SFG was developed as a surface probe some 20 years ago [1], and its use was extended to the electrochemical interface by Tadjeddine over a decade ago [2]. Several reviews examining the use of SFG in non-electrochemical environments exist [3-11]. Tadjeddine wrote two reviews on the application of SFG to electrochemical problems [12, 13). This chapter updates the Tadjeddine work and focuses on the promise and problems of state-of-the-art electrochemical SFG. 

I 5 Sum Frequency Generation Studies of the Electrified Solid/liquid Interface... 

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