Frozen electrolyte electrochemistry

The latter approach termed FREECE (FRozen Electrolyte ElectroChEmistry) has been pursued in our laboratory. In addition to increasing the available temperature down to approx. 120K which al lows one to vary the temperature by more than a factor of two, there are other interesting aspects of these technique ... 

Non-situ and ex situ studies can provide important information for understanding the properties of metal/electrolyte interfaces. The applicability of these methods for fundamental studies of electrochemistry seems to be firmly established. The main differences between common electrochemical and UHV experiments are the temperature gap (ca. 300 vs. 150 K) and the difference in electrolyte concentration (very high concentrations in UHV experiments). In this respect, experimental research on double-layer properties in frozen electrolytes can be treated as a link between in situ experiments. The measurements of the work functions... 

Exploration of electrochemistry in unconventional media. Electrochemical research has traditionally focused on measurements at electrodes fabricated from conductors immersed in solutions containing electrolytes. However, interfacial processes between other phases need to receive further attention, and they can be probed with electrochemical techniques. Electrochemistry can play a unique role in exploring chemistry under extreme conditions. The movement of charges in frozen electrolytes, poorly conducting liquids, and supercritical fluids can be experimentally measured with ultramicroelectrodes. Opportunities exist to study previously inaccessible redox processes in these media. Electrochemistry in environments of restricted diffusion... 

Other low-temperature studies have been motivated by the desire to characterize and understand processes occurring in unusual media. For example, the use of liquid ammonia [8-10] and liquid sulfur dioxide [11-13] naturally requires reduced temperatures unless high pressures are used, as is done for electrochemistry in supercritical fluids [14]. Frozen media are interesting systems in terms of mass transport phenomena and microstructural effects. Examples include glasses of acetonitrile and acetone [15], frozen dimethyl sulfoxide solutions [16,17], and the solid electrolyte HC104 5.5 H20 [18-20]. 

The last part of ionic electrochemistry, ionics, is about pure electrolytes. A few decades back this electrochemistry would have been all about high-temperature liquids (liquid common salt at 850 °C was the role model). However, this has changed, and the temperatures for eliminating the solvent have deaeased considerably. Some molten salts are now room temperature liquids. At the other end of the temperature scale are the molten silicates, where large polyanions predominate. These are important not only in the steel industry, where molten silicate mixtures form blast furnace slags, but also in the corresponding frozen liquids, the glasses. 

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