Fig. 3: Electrocatalytic properties of N_xM_0.2-xRO catalysts towards OER in 0.5 M H₂SO₄ electrolyte.

a, b Polarization curves with 90% iR-correction (a) of N_0.1M_0.1RO (with Rs = 4.47 ± 0.4 Ω at 0.4 mg cm⁻² loading and 3.15 ± 0.4 Ω at 3 mg cm⁻² loading), NRO (with Rs = 5.16 ± 0.5 Ω at 0.4 mg cm⁻² loading and 3.14 ± 0.5 Ω at 3 mg cm⁻² loading), MRO (with Rs = 4.82 ± 0.4 Ω at 0.4 mg cm⁻² loading and 3.70 ± 0.4 Ω at 3 mg cm⁻² loading), home-made RuO₂ (with Rs = 5.02 ± 0.5 Ω at 0.4 mg cm⁻² loading and 3.41 ± 0.5 Ω at 3 mg cm⁻² loading), and C-RuO₂ (with Rs = 4.71 ± 0.6 Ω at 0.4 mg cm⁻² loading and 3.70 ± 0.6 Ω at 3 mg cm⁻² loading) at a scan rate of 5 mV s⁻¹ and the corresponding overpotential values (b). Note, the non-iR corrected voltammograms and Nyquist plots of all the catalysts mentioned above are shown in Supplementary Figs. 16 and 17, the method for fabricating the electrodes is detailed in the Methods section. c The corresponding Tafel plots collected from N_xM_0.2-xRO, HM-RuO₂, and C-RuO₂. d Comparison of chronopotentiometry responses of N_0.1M_0.1RO, NRO, MRO, HM-RuO₂, and C-RuO₂ electrodes at current densities of 10, 100 or 200 mA cm⁻² (Top, 0.4 mg cm⁻² catalyst loaded on Ti mesh; Bottom, 3 mg cm⁻² catalyst loaded on the carbon paper). e S-number values collected from N_xM_0.2-xRO, HM-RuO₂, and C-RuO₂ electrode during the stability test in the top of the (d).