At the same pH in 0.05 M H 2 SO 4 instead of 0.1 M HClO 4 , O 2 AST shows a similar dissolu�on profile, with lower Fe detec�on but higher O 2 current densi�es (Figure ). This difference in current is unexpected as O 2 solubility is comparable at these acid concentra�ons. Meanwhile the total Fe loss is 2.3±0.1% in 0.05 M H 2 SO 4 and slightly higher in 0.1 M HClO 4 with 2.7±0.1% (Figure ). However, the charge normalized Fe dissolu�on is less than half in 0.05 M H 2 SO 4 , at 231±63 ng Fe mg FeNC -1 C -1 (Figure ).