fig3

Figure 3. (A) The typical cyclic voltammograms of the Cu/Cu_xO@MWCNTs-modified GC electrode, 0.1 M NaOH, a scanning rate of 50 mV·s^-1. (B) Successive 50-cycle cyclic voltammograms at Cu/Cu_xO@MWCNTs-modified GC electrode. (C) Nyquist plots at GC electrode (black curve), MWCNTs-modified GC electrode (blue curve), Cu_xO@MWCNTs-modified GC electrode (orange curve), Cu/MWCNTs-modified GC electrode (green curve) and Cu/Cu_xO@MWCNTs-modified GC electrode (red curve) in 0.1 M KCl comprising the 5 mM K₃[Fe(CN)₆] solution. Inset: the equivalent circuit. (D) CV curves of GC electrode (black curve), MWCNTs-modified GC electrode (blue curve), Cu_xO@MWCNTs-modified GC electrode (orange curve), Cu/MWCNTs-modified GC electrode (green curve) and Cu/Cu_xO@MWCNTs-modified GC electrode (red curve) with 1.0 mM glucose recorded at 20 mV·s^-1.