Figure 5.

Overpotential of the OER over IrO_x in the various solutions. Overpotential achieving 1, 10, and 20 mA cm⁻² over the IrO_x disk electrode in a RDE configuration and 100 mA cm⁻² over the IrO_x on Ti mesh are plotted as a function of the pH of the electrolyte bulk. Overpotentials at 1–20 mA cm⁻² were recorded in 0.1 mol kg⁻¹ electrolyte solutions at a disk rotation speed of 4900 rpm, a scan rate of −1 mV s⁻¹, and a reaction temperature of 298 K, adopted from data in Figures 1b and S2, and those at 100 mA cm⁻² were recorded in 1.0 mol kg⁻¹ buffered solutions at a reaction temperature of 298 K without stirring, adopted from data in Figure S16.