Electrochemical measurements for CPE behavior as a function of electrode potential were performed using an SP-200 potentiostat (Bio-Logic). A vertical electrochemical cell with a 3.5 cm 2 opening area (Redox.me) was employed. The working electrode consisted of a polycrystalline gold electrode with a (111) orientation (1.1 × 1.1 cm 2 , Arrandee). A platinum wire served as the counter electrode, and a saturated Ag/AgCl leakless electrode (ET072, Edaq) was used as the reference electrode. The working and counter/reference electrodes were housed in separate compartments of the electrochemical cell.