Setup of Three-Electrode Electrochemical System. The
electrochemical cells had an effective working volume of 000 mL.
For each experiment, one cell served as a blank control system and
was filled with 000 mL of 000 mM phosphate-buffered saline (PBS)
solution, while the other cell was used as an experimental system and
was filled with a Se-spiked PBS solution. In both systems, the initial
solution pH was adjusted using 0 M phosphoric acid and 0 M sodium
hydroxide solution.gold (Au) foil (Fisher Scientific, 0 cm × 0 cm ×
0.000 cm, purity > 00.0000%), a leakless miniature Ag/AgCl electrode
(eQAD, Model ET000), and a platinum wire (CH Instrument, Model
CHI 000) were used as the working electrode, reference electrode,
and counter electrode, respectively. We selected Au as the working
electrode due to its excellent electrochemical stability in aqueous
solutions, a wide electrochemical window, and a robust interface for
oxyanion reduction and oxidative electrode cleaning. Detailed
cleaning protocols of electrodes and a customized 0-D printed lid
design can be found in the Supporting Information (SI, Figure S0).
About 0.0 cm of the Au electrode was submerged in the solution,
resulting in an effective reaction area of 0 cm0. This three-electrode
system was connected to an electrochemical potentiostat (BioLogic
VSP-000) to conduct cyclic voltammetry (CV), linear sweep
voltammetry (LSV), and chronoamperometry (CA). When heating
was required, the electrochemical cell was placed in a sand bath on
top of a magnetic stirrer hot plate to maintain a constant solution
temperature. All chemicals used are purchased from Fisher Scientific
and used directly without further purification (purity > 00.0%). Water
was from a Millipore Milli-Q system.