How An Electrolyzer Works Mark Newell c.1992 Mark Newell An electrolyzer is a device that uses direct current electricity to break the bonds holding together water, (H2O), into its components hydrogen, (H), and oxygen, (O). An electrolyzer has three main components: an electrolyte, two electrodes and a separator. The electrolyte solution consists of distilled water and a salt, acid or base, and is held in a chamber. The electrodes are pieces of metal which sit in the electrolyte and pass current through the electrolyte. The separator is a barrier that physically separates the electrodes from each other yet allows current to flow between them. The Process The following reactions occur when the electrolyte is potassium hydroxide, (KOH). If another electrolyte is used the results will be the same though the reactions will be different. When DC electricity is connected to the two electrodes, current passes through the solution (H2O and KOH), decomposing the chemical bonds of the H2O molecules. Electrons enter into the chamber via the negative terminal, called a cathode, and cause a reaction. In this reaction four water molecules, 4H2O, are broken into eight positively charged hydrogen ions, 8H+, and four negatively charged oxygen ions, 4O--. Since the four oxygen ions are unstable in this state, each one quickly re- attaches to one hydrogen ion, forming four hydroxyl ions, 4OH-. The four remaining hydrogen ions, 4H+, combine with four elelectrons at the cathode to form hydrogen gas, 2H2. This half reaction is: 4e- + 4H2O į 4OH- + 2H2 The negative hydroxyl ions that were generated at the cathode are attracted to the positive electrode, called the anode. The electrolyte increases the conductivity of the water, allowing the hydroxyl ions to be pulled to the anode. At the anode another reaction takes place in which the four hydroxyl ions give up four electrons and form oxygen gas, O2, and two water molecules, 2H2O. These electrons leave the chamber via the anode to complete the circuit. The oxygen and hydrogen gas, kept separate by a barrier, bubble up through the electrolyte in to separate pipes and off to their points of use or storage. This reaction looks like: -4OH į O2 + 2H2O + 4e- The overall result of the two reactions looks like this: 2H2O į 2H2 + O2 Access: Author: Mark Newell, c/o Home Power, POB 520, Ashland, OR 97520 ù 916-475-3179