Fig. 4: OER mechanism of Pb-RuO₂.

a The iR-corrected polarization curves of Pb-RuO₂ and RuO₂ in 0.5 M H₂SO₄ solution with (dashed lines) and without (solid lines) 1 M methanol. b In situ Raman spectra of Pb-RuO₂ and RuO₂ obtained under various applied potentials. c Schematic illustration of the in situ DEMS. DEMS signals of ³²O₂, ³⁴O₂, and ³⁶O₂ from the gaseous products for ¹⁸O-labeled d Pb-RuO₂ and e RuO₂ catalysts in H₂¹⁶O aqueous H₂SO₄ electrolyte during three times of cycles. f The mass spectroscopy peak area ratio of ³⁴O₂/³²O₂ of Pb-RuO₂ and RuO₂.