Detection of Hydrogen in Corrosion of Copper in Pure Water

Copper is generally assumed to be immune to corrosion by water itself. However, this is not supported by any scientific experimental evidence. We have monitored hydrogen gas above immersed copper in distilled/deionised water. One apparatus is based on absolute pressure gauges and a palladium membrane. In addition, results from a 15 years exposure are presented. A transition from O₂-consuming to H₂-evolving copper corrosion is observed, which implies that copper can corrode by water itself. The complex corrosion product contains hydrogen and we have also measured a hydrogen uptake in the copper metal as a result of corrosion by water. Hydrogen uptake in the metal implies a sample thickness dependence in external hydrogen gas detection. The interpretation is described in terms of consumption of water by auto-protolysis which is not defined in gaseous water. The results are discussed in the perspective of the conventional potential-pH diagram for copper. Our findings are believed to have implications on the Swedish concept for final storage of spent nuclear fuel.