title: Interfacial water. The structure of interfacial water on gold electrodes studied by x-ray absorption spectroscopy.
abstract: The molecular structure of the electrical double layer determines the chemistry in all electrochemical processes. Using x-ray absorption spectroscopy (XAS), we probed the structure of water near gold electrodes and its bias dependence. Electron yield XAS detected at the gold electrode revealed that the interfacial water molecules have a different structure from those in the bulk. First principles calculations revealed that ~50% of the molecules lie flat on the surface with saturated hydrogen bonds and another substantial fraction with broken hydrogen bonds that do not contribute to the XAS spectrum because their core-excited states are delocalized by coupling with the gold substrate. At negative bias, the population of flat-lying molecules with broken hydrogen bonds increases, producing a spectrum similar to that of bulk water.
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Juan-Jesus
authors.initials: JJ
authors.lastname: Velasco-Velez
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Department of Chemistry, University of California, Berkeley, CA 94720, USA.
authors.forename: Cheng Hao
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Joint Center for Energy Storage Research, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Tod A
authors.initials: TA
authors.lastname: Pascal
authors.affiliation: Joint Center for Energy Storage Research, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Liwen F
authors.initials: LF
authors.lastname: Wan
authors.affiliation: The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Guo
authors.affiliation: Joint Center for Energy Storage Research, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: David
authors.initials: D
authors.lastname: Prendergast
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA. mbsalmeron@lbl.gov.
authors.forename: Miquel
authors.initials: M
authors.lastname: Salmeron