Hydrogen electrodes purity

A mercury-sulfate electrode served as a reference electrode. All electrode potentials are referred to the potential of the reversible hydrogen electrode in the same electrolyte and at the same temperature as the test electrode. Adsorption measurements were performed in the 0.5 M H2SO4 solution prepared using special purity B-5 sulfuric acid and water doubly-distilled. To remove oxygen dissolved in the electrolyte, pure helium or argon was bubbled through acid solution. 

Monofunctional and Polyfunctional Electrodes At monofunctional electrodes, one sole electrode reaction occurs under the conditions specified when current flows. At polyfunctional electrodes, two or more reactions occur simultaneously an example is the zinc electrode in acidic zinc sulfate solution. When the current is cathodic, metallic zinc is deposited at the electrode [reaction (1.21)] and at the same time, hydrogen is evolved [reaction (1.27)]. The relative strengths of the partial currents corresponding to these two reactions depend on the conditions (e.g., the temperature, pH, solution purity). Conditions may change so that a monofunctional electrode becomes polyfunctional, and vice versa. In the case of polyfunctional electrodes secondary (or side) reactions are distinguished from the principal (for the given purpose) reaction (e.g., zinc deposition). In the electrolytic production of substances and in other practical applications, one usually tries to suppress all side reactions so that the principal (desired) reaction will occur with the highest possible efficiency. 

In order to create a semiartificial device for hydrogen production, several components have to be optimized. Here we report about the construction of His-tagged PS1 and PS2 which should speed up and facilitate isolation of these reaction centers and also enable an oriented immobilization on the electrode surfaces of the device. Properties of isolated His-tagged PS1 and PS2 are compared with their WT counterparts in detail in order to find out whether there is an influence of the His-tag on purity, activity and heterogeneity. 

Mercury is a very widely used electrode material for studying cathodic processes owing to its very high hydrogen over-potential however, its anodic range is small. For use in dropping electrodes, mercury purity is most important. Its purification has been described extensively and is in four parts. 

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