Figure 8: = Comparison of the performance of the cathodes after the immersion treatment 1. (C1: cathode 1 treated in citrate buffer (pH 3.0)→citrate buffer (pH 3.0), C2: cathode 2 treated in acetate buffer (pH 4.0)→acetate buffer (pH 4.0), C3: cathode 3 treated in MES buffer (pH 5.5)→MES buffer (pH 5.5), C4: cathode 4 not treated→citrate buffer (pH 3.0), C5: cathode 5 not treated→ MES buffer (pH 5.5), C6: cathode 6 not treated→ Milli-Q water (pH 7.0)).