fig2

Figure 2. (A) LSV curves of Pt/C and M-N-C. (B) Percentage of HO₂^- productivity of M-N-C. (C) Numbers of electron transference of M-N-C. (D) The U₁ and U₂ on various square planar active sites are graphed as a function of O binding energy, where the U₁ represents the potential for four-electron ORR and U₂ for two-electron ORR. (E) U₁ and U₂ of the ORR procedure are graphed as a function of O binding energy on metal centers of all possible square pyramids, producing a high active plateau area, while the medium binding energy is about 0 eV. Reproduced from Zheng et al.^[56] by permission from Elsevier. (F) E_1/2 of M-N-C electrocatalysts based on various metals were tested by LSV. Reproduced from Peng et al.^[57] by permission from the American Chemical Society.