Structures of Water Molecules Adsorbed on a Gold Electrode under Negative Potentials

Two stable conformations of water hexamer Clusters on gold electrode under negative potentials have been identified by density functional theory calculations. Both form a ring Structure but with different orientations of free CH bonds. Ill one of the Structures, labeled as F-Type, four free OH bonds of the water molecules point toward the gold surface and remain stable over a wide range of the negative potential. The other Structure, labeled as S-Type, starts with five Such free OH bonds pointing toward the gold surface at the low negative potential and ends LIP with six of them at higher negative potential. From the energetic point of view, the S-Type Structure is more stable than the F-Type under the same Potential. By comparing the calculated Raman spectra with the experiment, it is found that S-Type Structures are the most possible surface adsorption state of water molecules at the electrochemical interface under very negative electrode potentials. It is believed that such a novel water Structure Could also exist Oil other negative charged Surfaces.