Alkaline Water Electrolysis

Alkaline water electrolysis splits water into hydrogen and oxygen using two electrodes immersed in a liquid alkaline electrolyte, typically a potassium or sodium hydroxide solution at 25 to 40 percent concentration, with a diaphragm between the electrodes that lets hydroxide ions pass while keeping the hydrogen and oxygen gases produced at each electrode apart. At the anode, hydroxide ions give up electrons to form oxygen and water, while at the cathode water molecules gain electrons to form hydrogen gas and fresh hydroxide ions, which then migrate back across the diaphragm to sustain the reaction. The technology dates to the late nineteenth century, when demand for hydrogen to fill lighter than air aircraft first drove commercial interest, and alkaline electrolysis remained commercially competitive with other hydrogen sources until steam reforming overtook it in the 1930s. Modern alkaline electrolyzers use nickel based catalysts rather than costly platinum group metals, letting them match or beat the efficiency of the newer proton exchange membrane electrolyzers while drawing on decades of proven industrial reliability, which keeps the technology relevant to current hydrogen production efforts.