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Electrolysis of water is the decomposition of water (H2O) into oxygen (O2) and hydrogen gas (H2) due to an electric current being passed through the water.

An electrical power source is connected to two electrodes, or two plates (typically made from some inert metal such as platinum, stainless steel or iridium) which are placed in the water. Hydrogen will appear at the cathode (the negatively charged electrode, where electrons enter the water), and oxygen will appear at the anode (the positively charged electrode). Assuming ideal faradaic efficiency, the amount of hydrogen generated is twice the number of moles of oxygen, and both are proportional to the total electrical charge conducted by the solution[1]. However, in many cells competing side reactions dominate, resulting in different products and less than ideal faradaic efficiency.

Electrolysis of pure water requires excess energy in the form of overpotential to overcome various activation barriers. Without the excess energy the electrolysis of pure water occurs very slowly or not at all. This is in part due to the limited self-ionization of water. Pure water has an electrical conductivity about one millionth that of seawater. Many electrolytic cells may also lack the requisite electrocatalysts. The efficiency of electrolysis is increased through the addition of an electrolyte (such as a salt, an acid or a base) and the use of electrocatalysts.

Currently the electrolytic process is rarely used in industrial applications since hydrogen can currently be produced more affordably from fossil fuels.[2]

Revised text

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Electrolysis of water can be observed by passing direct current from a battery of other DC power supply through water to produce oxygen (02) and hydrogen (H2) gas.

An electrical power source is connected to two electrodes (an electrical conductor), or two plates (typically made from some inert metal such as platinum or stainless steel) which are placed in the water. Hydrogen will appear at the cathode where reduction happens (the negatively charged electrode, where electrons enter the water), and oxygen will appear at the anode where oxidation happens (the positively charged electrode). Assuming ideal faradaic efficiency, the amount of hydrogen generated is twice the number of moles of oxygen,because of the 2:1 ratio and both are proportional to the total electrical charge conducted by the solution. However, in many cells competing side reactions dominate, resulting in different products and less than ideal faradaic efficiency.

Electrolysis of pure water requires excess energy in the form of overpotential to overcome various activation barriers. Without the excess energy the electrolysis of pure water occurs very slowly or not at all. This is in part due to the limited self-ionization of water. Pure water has an electrical conductivity about one millionth that of seawater. Many electrolytic cells may also lack the requisite electrocatalysts. The efficiency of electrolysis is increased through the addition of an electrolyte (such as a salt, an acid or a base) and the use of electrocatalysts. Currently the electrolytic process is rarely used in industrial applications since hydrogen can be produced more affordably from fossil fuels.[1]

Comments

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  • I like that you added that oxidation happens at the anode, and that reduction happens at the cathode.
  • I noticed that all of the references to other Wikipedia pages have been removed. This makes it more difficult for readers to look up terms with which they are not familiar. I suggest that you keep the Wikilinks (you can make a term a Wikilink by adding [[ ]] around it. Also, try not to cut out the first reference in the original text (unless the reference is bad, in which case you are awesome for looking up the source to check its integrity).
  • Some other minor edits:
  1. When you write O for oxygen, use O instead of 0. Ex: H2O, instead of H20. You might also want to use the subscript for 2.
  2. Line 1: I think you mean "battery or other DC power supply."
  3. Line 4: I recommend changing "because of the 2H to 10 ratio" to "because of the 2:1 H to O ratio in the balanced chemical equation."
  4. In the last sentence, there is something else you could change from the original text. There is no need to say currently twice, the second "currently" can be removed.

--REEstudent (talk) 03:23, 30 May 2013 (UTC)

  1. ^ Carmo, Marcelo; Fritz, David L.; Mergel, Jürgen; Stolten, Detlef (2013). "A comprehensive review on PEM water electrolysis". Journal of Hydrogen Energy. 38 (12): 4901–4934. doi:10.1016/j.ijhydene.2013.01.151.{{cite journal}}: CS1 maint: date and year (link)
  2. ^ Staff (2007). "Hydrogen Basics — Production". Florida Solar Energy Center. Retrieved 2008-02-05.