Fig. 3: Electrocatalytic 2e⁻ ORR performance of Se‒Pt NPs under acidic electrolytes.

a RRDE voltammograms at 1600 rpm in O₂-saturated 0.1 M HClO₄ with the ring current (dashed lines) and disk current (solid lines) for C support, Pt NPs, and Se‒Pt NPs with different shell thicknesses (without iR corrected) (scan rate: 10 mV s⁻¹, loading amount: 3 μg_Pt; O₂ flow rate: 10 mL min⁻¹; temperature: 25 °C). b Values of the selectivity (%) calculated from the RRDE polarization curves. The shaded area represents the error bar derived from three independent measurements. c The comparison of the selectivity values of Se₂‒Pt NPs in different electrolytes and the reported electrocatalysts. d Schematic illustration of an ideal catalyst surface that inhibit the disproportionation reaction and electrochemical reduction reaction. e electrochemical reduction reaction studied by following a similar method for ORR test but using a degassed 0.1 M HClO₄ containing 10 mM H₂O₂ and (f) disproportionation reaction measured by adding 10 mg catalysts into 10 mM H₂O₂ aqueous solution at room temperature. g The photo taken after adding 10 mg Pt NPs and Se₂‒Pt NPs into 10 mM H₂O₂ aqueous solution at room temperature.