1：Experimental Design and Method Selection

Time resolved Raman spectroelectrochemistry (TR-Raman-SEC) was used to study the EC-SOERS phenomenon. Cyclic voltammetry (CV) was performed between -0.25 V to +0.55 V beginning at +0.10 V in the anodic direction with a scan rate of 0.02 V·s-1 and a step potential of 2 mV.

2：Sample Selection and Data Sources

A silver disk electrode was used as the working electrode. The electrode was polished with silica 0.5 μm particle size, rinsed with ultrapure water, and sonicated to eliminate silica traces.

3：List of Experimental Equipment and Materials

SPELEC RAMAN instrument (Metrohm-DropSens) with a 785 nm laser source, Raman probe (DRP-RAMANPROBE, Metrohm-DropSens), home-made cell for silver disk electrode, home-made Ag/AgCl reference electrode, platinum wire counter electrode, perchloric acid (HClO4, 60 %, Sigma-Aldrich), uric acid (UA, 99+%, Acros Organics), potassium chloride (KCl, 99+%, Acros Organics).

4：Experimental Procedures and Operational Workflow

The electrode was polished, rinsed, and sonicated before experiments. Raman spectra were collected with an integration time of 1 s and a laser power of 80 mW (254 W·cm-2). The electrochemical experiment was performed in a solution containing UA 2·10-4 M + HClO4 0.1 M + KCl 5·10-3 M.

5：Data Analysis Methods

The evolution of the Raman signal with potential (or time) was analyzed to understand the dynamic of the substrate preparation in presence of a Raman probe molecule. SEM was used to characterize the working silver electrodes at various stages of the electrochemical activation.