File Name : figure s1.tif

Caption : figure s1. average half-cell potentials <i>ir</i>-corrected under different operating current densities. solution resistance measured through eis was 5.3 ± 0.6 ω.

File Name : figure s2.tif

Caption : figure s2. electrolyte temperature during electrochemical reaction for <i>j</i> of 20, 45, 70 and 95 ma cm<sup>-2</sup>. electrolyte was 0.5 m na<sub>3</sub>po4, [pa]<sub>0</sub> 2 m, ph<sub>0</sub> 7.