Deconvolution of the Voltammetric Features of a Pt(100) Single-Crystal Electrode.

The Pt(100) single-crystal electrode shows four voltammetric features in acid electrolytes, but the precise corresponding surface phenomena remain unresolved. Herein, a deconvolution of the classical "hydrogen region" from the "hydroxyl and anion region" is attempted by the comparison of voltammetric behavior of Pt(100) and G ML Pt(100) electrodes. A systematic study performed on Pt(s)-[ n (100) × (111)] and Pt(s)-[ n (100) × (110)] electrodes reveals that the feature at E PI = 0.30 V RHE corresponds to pure hydrogen adsorption taking place at (111) step sites vicinal to (100) domains, while the peak at E PII = 0.36 V RHE actually involves hydroxyl replacing hydrogen at (100) domains. An analysis examined for H 2 SO 4 , HClO 4 , CH 3 SO 3 H, and HF demonstrates that the specific (H)SO 4 - adsorption commences at E PIII = 0.40 V RHE and effectively suppresses the formation of hydroxyl at the (100) terrace at higher potentials 0.40 < E PIV < 0.75 V RHE . Non-specifically adsorbing anions (ClO 4 - , CH 3 SO 3 - and F - ) would only interact with the hydroxyl phase formed on the Pt(100) terrace in both potential regions.