As before, the CVs exhibited a single oxidation peak and Ep,ox shifting toward less positive potentials as the pH increased (Figure and Table ). Additionally, on CVs we observed a cathodic peak related to the Cu(III) reduction. Notably, for a scan rate of 5 V/s, the reduction peak was visible in the pH range from 5.0 to 6.5. At pH 7.4 the reduction signal has almost disappeared.