Electrocatalytic reduction of carbon dioxide on platinum single crystal electrodes modified with adsorbed adatoms

Platinum single crystal electrodes, Pt(h k l), represent ideal materials where studying the effect of adatoms presence in surface sensitive reactions such as carbon dioxide reduction and formic acid oxidation. In particular, we study here if some of the platinum single crystal electrodes modified with adsorbed adatoms already reported as highly active electrocatalysts for formic acid oxidation can act as bifunctional electrocatalysts and present high activity for CO2 reduction as well. After testing 12 different modified platinum single crystal electrodes, we proved by cyclic voltammetry that only Bi–Pt(1 1 1), Te–Pt(1 1 1), and Sb–Pt(1 0 0) electrodes show a significant current increase in the presence of CO2 in neutral bicarbonate buffer solution. Thus, we demonstrate their behavior as active bifunctional electrocatalysts for carbon dioxide reduction and formic acid oxidation reactions. Moreover, we provide the voltammetric fingerprint for several Bi-, Se-, Te, and Sb–Pt(h k l) electrodes in both, acid and neutral aqueous solution.