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Title: Water as a Promoter and Catalyst for Dioxygen Electrochemistry in Aqueous and Organic Media [Water as Promoter and Catalyst in Dioxygen Electrochemistry at Aqueous and Organic Electrified Interfaces].

Water and oxygen electrochemistry lies at the heart of interfacial processes controlling energy transformations in fuel cells, electrolyzers, and batteries. Here, by comparing results for the ORR obtained in alkaline aqueous media to those obtained in ultradry organic electrolytes with known amounts of H2O added intentionally, we propose a new rationale in which water itself plays an important role in determining the reaction kinetics. This effect derives from the formation of HOad···H2O (aqueous solutions) and LiO2···H2O (organic solvents) complexes that place water in a configurationally favorable position for proton transfer to weakly adsorbed intermediates. We also find that, even at low concentrations (<10 ppm), water acts simultaneously as a promoter and as a catalyst in the production of Li2O2, regenerating itself through a sequence of steps that include the formation and recombination of H+ and OH-. We conclude that, although the binding energy between metal surfaces and oxygen intermediates is an important descriptor in electrocatalysis, understanding the role of water as a proton-donor reactant may explain many anomalous features in electrocatalysis at metal-liquid interfaces.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1] ;  [5] ;  [6] ;  [2] ;  [7] ;  [1] ;  [1] ;  [8] ;  [2] ;  [8] ;  [3] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research; Univ. of Illinois at Urbana-Champaign, IL (United States)
  5. J. Heyrovsky Inst., Prague (Czech Republic). Dept. of Electrochemical Materials
  6. Northwestern Univ., Evanston, IL (United States)
  7. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research; Univ. of Ljubljiana (Slovenia)
  8. Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research
Publication Date:
Report Number(s):
SAND-2014-18453J
Journal ID: ISSN 2155-5435; 540206
Grant/Contract Number:
AC04-94AL85000; AC02-06CH11357
Type:
Published Article
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1223600
Alternate Identifier(s):
OSTI ID: 1343272