Water at electrode-electrolyte interfaces: combining HOD vibrational spectra with ab initio-molecular dynamics simulations We have undertaken a vibrational study of the structure of interfacial water and its potential dependence using H2O:D2O mixtures to explore the O-H and O-D stretching modes of HOD as well as the bending modes of HOD and H2O. Due to the symmetry reduction, some of the complexity characteristic of the vibrational spectrum of water is removed in HOD.