Proton Wires via One-Dimensional Water Chains Adsorbed on Metallic Steps

The process of proton transfer is here analyzed for one-dimensional water chains adsorbed on metallic steps. When the water chain contains a hydronium and a hydroxyl ion, two different mechanisms are possible, depending on the metal substrate. On coinage metals (Ag, Au), recombination is observed through a spontaneous Grotthuss mechanism. On more reactive surfaces (Pd and Pt), the hydronium ion is unstable and releases a proton that adsorbs onto the metal, leaving the negatively charged OH(-) unbalanced. In this case, the negative charge can be transferred along the wire with very low activation barriers.