Emprove exp h2so4

Milli-Q water (resistivity >18.2 MΩ·cm,
TOC < 5 ppb) was used for all experiments in this work. Prior to
each experiment, all cell compartments were cleaned by soaking in
an aqueous solution of 1 g·L^–1 KMnO₄ (Fluka, ACS reagent) and 0.5 M H₂SO₄ (Fluka,
ACS reagent) overnight. The solution was subsequently drained, and
the cell compartments were rinsed with a dilute piranha solution (1:3
v/v of H₂O₂ (Merck, Emprove exp)/H₂SO₄) to remove residual KMnO₄ and MnOx. Afterward,
the cell compartments were cleaned by repetitively rinsing and boiling
with Milli-Q water to remove all inorganic contaminants.

Ultrapure water (resistivity
> 18.2 MΩ·cm, Millipore Milli-Q) was used for all experiments
in this work. Prior to each experiment, all cell compartments were
cleaned by storing them in a potassium permanganate solution (1 g
L^–1 KMnO₄ (Fluka, ACS reagent) in 0.5
M H₂SO₄ (Fluka, ACS reagent)) overnight. The
solution was subsequently drained, and the cell compartments were
rinsed with a dilute piranha solution (1:3 v/v of H₂O₂ (Merck, Emprove exp)/H₂SO₄) to remove
residual KMnO₄ and MnO_x. Afterward,
the cell compartments were cleaned by repetitively rinsing and boiling
with Milli-Q water to remove all inorganic contaminants. Electrolytes
were prepared from LiClO₄ (Sigma-Aldrich, ≥99.99%
trace metal basis), NaClO₄ (Sigma-Aldrich, ≥99.99%
trace metal basis), KClO₄ (Sigma-Aldrich, ≥99.99%
trace metal basis), NaClO₄ (Sigma-Aldrich, ≥99.99%
trace metal basis), H₂SO₄ (Merck, Suprapur,
96%), PdSO₄ (Sigma-Aldrich, 99.99% trace metal basis),
and HClO₄ (Sigma-Aldrich, Ultrapure, 70%). In this work,
a Pt wire (0.5 mm diameter, MaTecK, 99.9%) was used as the counter
electrode, a reversible hydrogen electrode (RHE) was used as the reference
electrode, and all of the potentials were corrected for ohmic drop
and controlled with an Autolab PGSTAT302N potentiostat.