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Title: Role of Cu-Ion Doping in Cu-α-MnO 2 Nanowire Electrocatalysts for the Oxygen Reduction Reaction

The role of Cu-ion doping in α-MnO 2 electrocatalysts for the oxygen reduction reaction in alkaline electrolyte was investigated. Copper doped α-MnO 2 nanowires (Cu-α-MnO 2) were prepared with varying amounts of Cu 2+ using a solvothermal method. The electrocatalytic dataindicates that Cu-α-MnO 2 nanowires have higher terminal current densities, enhanced kinetic rate constants, and improved charge transfer resistances that trend with Cu-content, exceeding values attained by α-MnO 2 alone. The observed improvement in catalytic behavior correlates with an increase in Mn 3+ content for the Cu-α-MnO 2 nanowires. The Mn 3+/Mn 4+ couple is themediator for the rate-limiting redox driven O 2 -/OH - exchange. It is proposed that O 2 adsorbs viaan axial site (the e g orbital on the Mn 3+ d 4 ion) at the surface, or at edge defects, of the nanowireand that the increase in covalent nature of the nanowire with Cu-ion doping leads to stabilization of O 2 adsorbates and faster rates of reduction. This work is applicable to other manganese oxide electrocatalysts and shows for the first time there is a correlation for manganese oxides between electrocatalytic activity for the ORR in alkaline electrolyte and an increase in Mn 3+ character ofmore » the oxide.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Materials, Devices & Energy Technologies
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Materials Characterization & Performance
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Advanced Materials Laboratory
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Physics based Microsystems
Publication Date:
Report Number(s):
SAND2014-1394J
Journal ID: ISSN 1932-7447; 503570
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 118; Journal Issue: 31; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1140890