Selective Room-Temperature Catalytic Decomposition of Hypochlorite to Oxygen and Chloride.

Thermochemical cycles for hydrogen production involve a series of reactions, with water decomposition as the net result. One of the reactions frequently encountered in these cycles is the reverse Deacon reaction, where chlorine reacts with water vapor to form hydrogen chloride at high temperatures. An alternative, lower-temperature approach involves introducing chlorine to liquid water, yielding hydrochloric acid and hypochlorous acid. The hypochlorous acid can be further decomposed to hydrochloric acid and oxygen by catalytically induced reaction. The catalytic activity of ruthenium and iridium oxide nanopowders, along with UV light, was investigated for the decomposition of hypochlorous acid. Using Raman spectroscopy and mass spectrometry, we demonstrated that both catalysts facilitate decomposition to oxygen, while UV light promotes decomposition to chlorate ions. Ruthenium-(IV) oxide exhibited superior catalytic activity compared to iridium-(IV) oxide in both alkaline and acidic media. Both catalysts showed excellent recyclability, maintaining consistent activity after five consecutive tests. Structural stability was confirmed via XRD, Raman spectroscopy, and TEM analysis.