Figure 3.

Cyclic voltammograms obtained for HER on a) Au polycrystalline surface and b) Au(111) surface at 2500 rpm in 0.1 M NaOH (pH 13), 0.01 M NaOH +0.09 M NaClO₄ (pH 12), 0.001 M NaOH + 0.099 M NaClO₄ (pH 11), and 0.0001 M NaOH +0.0999 M NaClO₄ (pH 10), in Ar‐saturated environment at 25 mV s⁻¹. Steady‐state current obtained at 50 mV potential steps at 2500 rpm on c) Au polycrystalline surface and d) Au(111) surface at different pH values (same as above), plotted as function of the applied overpotential on the y‐axis and the logarithm of the current density on the x‐axis where the corresponding Tafel slopes at each pH value are indicated next to the plot. Tafel slopes obtained from the differentiation of the cyclic voltammograms in (a) and (b) plotted as a function of the applied potential (vs. RHE) for e) Au polycrystalline and f) Au (111) at different pH values.