Quantum-chemical investigation of interaction of water molecules with surfaces of metal electrodes

The adsorption of water molecules at the surface of clusters (10 + 6) of ga llium and indium is calculated by ab initio quantum-chemical methods of MO of Hartree-Fock and the density functional (scheme B3LYP). The energy of wa ter adsorption Delta E-ads is found to increase in the series "hollow" appr oximate to "bridge" < "on-top" and equals 37.2 and 23.4 kJ mol(-1) for gall ium and indium in the on-top position, respectively. Comparing the results to the literature data shows that the values of Delta E-ads for gallium and mercury are close, which points to virtually identical hydrophilicity of t hese metals and contradicts the known,hypothesis about substantial;hydrophi licity of gallium. The adsorption interaction of water with gallium is show n to have some specific features as compared with mercury. Estimates of the dipole reorientation point to a high mobility df water molecules in the ED L field. The surface diffusion coefficient is calculated. Possible reasons for different capacitances of dense parts of EDL for mercury and gallium ar e discussed.