Electrolysis is the process by which an electric current is passed through a substance to affect a chemical change. The chemical change occurs when the substance loses electrons (oxidation) or gains them (reduction). In the two experiments listed below, the first reactive substance is water and the second one is a copper sulfate solution.
Electrolysis is used to remove hair, split compounds, and in the manufacturing process to decorate, strengthen, and make metal surfaces more resistant to rust.
Water electrolysis is a well-established technology that has been used for almost one century for miscellaneous application in the industry (food industry, power plants, metallurgy, etc.). Nowadays, it is also considered as a key process that can be used for the production of high-purity hydrogen from water and renewable energy sources. It is expected that in the near future, water electrolyzers will occupy an increasingly prominent place for the decentralized production of hydrogen, for example, in hydrogen-fueling stations. Thus, in spite of its long industrial history, this is still the focus of several ambitious R&D programs and investments worldwide. There are different water electrolysis technologies. The difference between them comes from the temperature of operation and the pH of the electrolyte. The alkaline process is the oldest and a more mature one. But SPE water electrolysis has been making very significant progresses over the last years and because of its large potential for further improvement, it is expected to play a significant role in view of the so-called hydrogen economy and the large production of hydrogen of electrolytic grade from renewable energy sources. The high-temperature water electrolysis process is probably more efficient. However, it is faced with critical challenges (especially, in material science). Such challenges will have to be overcome before any market application can be considered.