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

Abstract

<p>Formation of corrosion products on zinc was investigated with in-situ Raman and FTIR when exposed to wet supercritical carbon dioxide (scCO<sub>2</sub>) and subsequent depressurization. Zinc oxide (ZnO) and smithsonite (ZnCO<sub>3</sub>) formed on zinc in scCO<sub>2</sub>. The dissolved water precipitated as liquid water in the reaction cell during depressurization. Formation of ZnO, ZnCO<sub>3</sub> 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.</p>