Abstract
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.