Charge transfer-resistance in nitrogen-doped/undoped graphene: Its influence on the electro-catalytic reduction of H2O2

Nitrogen doped (N-Gr) and undoped (TRGO) graphene were chemically synthesized and characterized by TEM, STEM-EDX and XPS. The electrochemical reduction of H2O2 was investigated with bare glassy carbon (GC) electrode and with GC modified with each graphene sample. The active area of TRGO/GC and N-Gr/GC modified electrodes were found to be 0.75 and 0.295 cm2, respectively. Both were considerably larger than that of bare GC (0.07 cm2). We carefully looked at the kinetic of interfacial electron transfer process and found that the charge-transfer resistance (Rct) of TRGO/GC electrode (7.83 × 106 Ω) was significantly lower than that of N-Gr/GC electrode (4.81 × 107 Ω) or bare GC (1.74 × 109 Ω). Interestingly, although TRGO/GC electrode had the largest active area and the smallest charge transfer resistance, it did not promote the H2O2 electrochemical reduction. In contrast, N-Gr/GC modified electrode exhibited an enhanced electro-catalytic activity towards H2O2 reduction, which was related to the presence of heterogeneous atoms into the sp2 carbon network.