Figure 4. RDE data for electrode modified with G65YCu_BMb with Cu²⁺.

(a) Linear sweep voltammogram of G65YCu_BMb with Cu²⁺ in air-saturated pH 7, 100 mM phosphate buffer solution at 100 mV s⁻¹ scan rate, potentials are scaled relative to NHE and a Pt counter electrode is used. Data are collected at different rotation speeds (200 r.p.m.—red, 400 r.p.m.—purple, 600 r.p.m.—green, 800 r.p.m.—blue). (b) Plot of i_cat⁻¹ for G65YCu_BMb-bearing bioelectrode at −300 mV potential and at multiple rotation rates, with the inverse square root of the angular rotation rate (ω^−1/2) (c) Difference between the potential for O₂ reduction (E_ORR) and the midpoint reduction potential of Fe^3+/2+ redox couple (E^1/2).