OH-···Au Hydrogen Bond and Its Effect on the Oxygen Reduction Reaction on Au(100) in Alkaline Media.

Using ab initio molecular dynamics simulations with fully solvated ions, we demonstrate that solvated OH- forms a stable hydrogen bond with Au(100). Unlike the hydrogen bond between H2O and Au reported previously, which is more favorable for negatively charged Au, the OH-···Au interaction is stabilized when a small positive charge is added to the metal slab. For electro-catalysis, this means that while OH2···Au plays a significant role in the hydrogen evolution reaction, OH-···Au could be a significant factor in the oxygen reduction reaction in alkaline media. It also points to a fundamental difference in the mechanism of oxygen reduction between gold and platinum electrodes.