Thermodynamics and kinetics of steam splitting over a potassium aluminosilicate electrolyte

A novel system using a potassium aluminosilicate electrolyte under applied potential that is able to split H₂O (or OHˉ) into H₂ and 1/2O₂ (or O₂ ^2-) with higher yields than the value deduced from Faraday"s law is presented. There were three steps by which H₂ and O₂ were generated stoichiometrically, and it was predicted that the high yields were due to the occurrence of chemically endothermic reactions: dehydration of the catalytic cell at a temperature below 100°C (step I), disproportionation of KOH (2KOH→H₂+K₂O₂) at a temperature around 200°C (step II), and disproportionation of K₂O (2K₂O→K₂+K₂O₂) at a temperature above 500°C (step III). So-called Nemca might be caused in the course of step III, since the rate of H₂ was ca 10² times larger than the value deduced from Faraday"s law. This revised version was published online in August 2006 with corrections to the Cover Date.