Fig. 3

a Cyclic Voltammograms (CVs) recorded with ZtrLac1A modified low-density GE in N2 (black line) and in O2 (red line); (inset Fig. 3a) subtracted curve in order to determine the onset of O2 reduction. b CVs recorded with GE/Os-polymer/ZtrLac1A under N2 (black line) and in O2 (red line) conditions. (Inset Fig. b) subtracted curve in order to determine the onset of O2 reduction. Conditions: 0.1 M acetate buffer at pH 4.0 in 0.1 M NaClO4; scan rate 10 mVs− 1