The three-electrode j-E measurement for HER on a Pt-coated Ni mesh HER cathode measured in 1 M H2SO4 is shown in Figure , along with the j-E measurements for the GEOR and OER electrocatalysts in 2 M NaOH (with 20% (w/w) glycerol for GEOR). For combining the HER cathode in the acidic electrolyte (aHER) and the OER anode in a single cell, the difference in electrode potentials (∆𝐸) at -10.0 mA cm -2 is -0.78 V. A similar comparison of the aHER cathode and the GEOR anode results in ∆𝐸= 0.28V, which incorrectly suggests that the reaction is spontaneous. However, accounting for VBPM in both LLA resulted in predictions of negative, electrolytic cell potentials for both cells. The predicted operating cell potentials are Vop = -1.61 V for the aHER|BPM|OER cell and Vop = -0.55 V for the aHER|BPM|GEOR cell.