Fig. 4: Electrochemical and spectroscopic verification of LOM.

a LSV curves measured in KOH electrolytes with pH = 12.5, 13, 13.5, and 14 (left), j at 1.45 V vs. RHE plotted in log scale as a function of pH (right), from which the proton reaction orders (ρ^RHE = ∂logj/∂pH) were derived. The loading of catalysts is ~1 mg cm⁻², and the solution resistance is 2.0 Ω. b Polarization curves of Au_SA-MnFeCoNiCu LDH and MnFeCoNiCu LDH in 1.0 M KOH and 1.0 M TMAOH (left), shift of overpotential at 100 mA cm⁻² (Δη₁₀₀) and Tafel slopes from KOH to TMAOH (right). c Raman spectra of Au_SA-MnFeCoNiCu LDH and MnFeCoNiCu LDH, measured after running at 1.45 V vs. RHE for 30 min in 1.0 M TMAOH and 1.0 M KOH solutions and washing with deionized water. d In situ Raman spectra of MnFeCoNiCu LDH. e In situ Raman spectra of Au_SA-MnFeCoNiCu LDH. f Mass spectrometric results by ¹⁸O isotope-labeling experiments. The signals were normalized by initial intensity of ¹⁶O₂.