Oxygen reduction and hydrogen evolution–oxidation reactions on Cu(hkl) surfaces

Taking advantage of the ring collection properties of the rotating ring–disk electrode with a single-crystal copper disk, we have shown that the oxygen reduction reaction and the hydrogen evolution–oxidation reactions on Cu(111) and Cu(100) surfaces in sulfuric acid are structure-sensitive processes. An interpretation of the structural sensitivity is presented, based on the premise of the structure-sensitive adsorption of (bi)sulfate anions. We have observed that the ordering kinetics of the (bi)sulfate on Cu(hkl) have an important role in the mechanism of the oxygen reduction reaction.