Formation of corrosion products on zinc in wet supercritical and subcritical CO2: In-situ spectroscopic study

Formation of corrosion products on zinc was investigated with in-situ Raman and FTIR when exposed to wet supercritical carbon dioxide (scCO2) and subsequent depressurization. Zinc oxide (ZnO) and smithsonite (ZnCO3) formed on zinc in scCO2. The dissolved water precipitated as liquid water in the reaction cell during depressurization. Formation of ZnO, ZnCO3 and a needle-like zinc hydroxy carbonate species on zinc was observed inside a sessile water droplet during conditions simulating the depressurization phase. Addition of oxygen accelerated the formation of the carbonate species due to higher cathodic activity that increased zinc dissolution.