particular, Cu-N-rGO exhibits an R1 value equal to 70 Ω, which is smaller than that of N-rGO sample (82 Ω), confirming that the presence of Cu2+-based complexes is effective in increasing the material conductivity, as suggested by the presence of occupied In addition, the states near the Fermi charge transfer at the interface is also enhanced for the Cu-N-rGO catalyst, as evidenced by the lower R2 value of 3098 Ω with respect to 4315 Ω for the N-rGO sample.