A new structure of water layer on Cu(111) electrode surface during hydrogen evolution.

A layered structure of water molecules formed on a Cu(111) electrode surface during hydrogen evolution in sulfuric acid solution was studied by surface X-ray diffraction and infrared reflection absorption methods. Water molecules in the surface layers take a closest pack-like stacking structure with nearest-neighbor oxygen-oxygen distances in intra-(0.322(5) nm) and inter-(0.275(15) nm) layers of multi-domains; the infrared spectra of the layered water on the Cu electrode surface showed the existence of free OH(OD) and hydrogen-bonded OH(OD) of water molecule.