| AVS 56th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS1-WeM |
| Session: | Water/Surface Interactions & Environmental Chemistry I |
| Presenter: | J. Newberg, Lawrence Berkeley National Lab |
| Authors: | J. Newberg, Lawrence Berkeley National Lab D. Starr, Lawrence Berkeley National Lab E. Mysak, Lawrence Berkeley National Lab S. Yamamoto, Stanford Synchrotron Radiation Lab S. Kaya, Stanford Synchrotron Radiation Lab T. Kendelewicz, Stanford University S. Porsgaard, Lawrence Berkeley National Lab M. Salmeron, Lawrence Berkeley National Lab G. Brown, Jr., Stanford University A. Nilsson, Stanford Synchrotron Radiation Lab H. Bluhm, Lawrence Berkeley National Lab |
| Correspondent: | Click to Email |
Under ambient relative humidity (RH) conditions thin film water coats metals, insulators, semiconductors and ice surfaces [1]. The water-oxide interface plays an important role in chemical, biological and industrial systems [2]. Water on MgO(100) is one of the most widely studied systems, both theoretically and experimentally, due to the simple rock salt cubic structure of MgO. Carbon dioxide is an important greenhouse gas, and the carbonation of MgO in mineral deposits has been suggested as a potential medium for carbon dioxide sequestration [3]. Here we present results from the investigation of the interaction of water and carbon dioxide with MgO(100)/Ag(100) films using the ambient pressure photoemission spectroscopy (APPES) setup at beamline 11.0.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory [4]. With APPES we can quantitatively probe on a molecular level the chemical changes of the MgO(100) surface using XPS and NEXAFS while in equilibrium with water and/or carbon dioxide gases. Using 0.5 Torr isobars, we have characterized the uptake of water on MgO surfaces up to 20% RH. At roughly 0.1% RH, the MgO surface is fully hydroxylated with a ML of OH and sub-ML molecular water. At 20% RH there is roughly 1 ML of molecular water interacting with a fully hydroxylated MgO surface. Preliminary results for carbon dioxide reactivity with MgO to form carbonate showed dependency on whether the MgO surface was dry (oxide terminated) or wet (hydroxyl/water terminated). Thus, the presence of thin film water influences carbon sequestration. Ongoing studies are addressing the influences of changing RH on MgO carbonation.
References
[1] G.E Ewing 2006 Chem Rev. 106 1511.
[2] G.E. Brown et al. 1999 Chem. Rev. 99 77.
[3] T. Koljonen et al. 2004 Energy 29 1521.
[4] H. Bluhm et al. 2007 MRS Bulletin 34 1022.