Figure 4: Overpotential of the HOR/HER on Pt as a function of the HBE.

The overpotential for the HOR is at i=0.5ilim and the overpotential for the HER is at i=−1 mA cm−2disk in all pH-buffered electrolytes on Pt(110) (solid symbols) and (100) (open symbols) surfaces. Error bars are s.d. of at least two sets of experimental repeats.