Title: Understanding the effects of cationic dopants on α-MnO₂ oxygen reduction reaction electrocatalysis

Abstract

Nickel-doped α-MnO₂ nanowires (Ni–α-MnO₂) were prepared with 3.4% or 4.9% Ni using a hydrothermal method. A comparison of the electrocatalytic data for the oxygen reduction reaction (ORR) in alkaline electrolyte versus that obtained with α-MnO₂ or Cu–α-MnO₂ is provided. In general, Ni-α-MnO₂ (e.g., Ni-4.9%) had higher n values (n = 3.6), faster kinetics (k = 0.015 cm s^–1), and lower charge transfer resistance (R_CT = 2264 Ω at half-wave) values than MnO₂ (n = 3.0, k = 0.006 cm s^–1, R_CT = 6104 Ω at half-wave) or Cu–α-MnO₂ (Cu-2.9%, n = 3.5, k = 0.015 cm s^–1, R_CT = 3412 Ω at half-wave), and the overall activity for Ni–α-MnO₂ trended with increasing Ni content, i.e., Ni-4.9% > Ni-3.4%. As observed for Cu–α-MnO₂, the increase in ORR activity correlates with the amount of Mn³⁺ at the surface of the Ni–α-MnO₂ nanowire. Examining the activity for both Ni–α-MnO₂ and Cu–α-MnO₂ materials indicates that the Mn³⁺ at the surface of the electrocatalysts dictates the activity trends within the overall series. Single nanowire resistance measurements conducted on 47 nanowire devices (15 of α-MnO₂, 16 of Cu–α-MnO₂-2.9%, and 16 of Ni–α-MnO₂-4.9%) demonstrated that Cu-doping leads to a slightly lower resistance value than Ni-doping, although bothmore » were considerably improved relative to the undoped α-MnO₂. As a result, the data also suggest that the ORR charge transfer resistance value, as determined by electrochemical impedance spectroscopy, is a better indicator of the cation-doping effect on ORR catalysis than the electrical resistance of the nanowire.« less

Authors:

Lambert, Timothy N.  ^[1];

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Vigil, Julian A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-0205-2379"

White, Suzanne E. ^[1]; Delker, Collin J. ^[1]; Davis, Danae J. ^[1]; Kelly, Maria ^[1]; Brumbach, Michael T. ^[1]; Rodriguez, Mark A. ^[1]; Swartzentruber, Brian S. ^[1]

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+ Show Author Affiliations

1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Publication Date:

Mon Jan 09 00:00:00 EST 2017

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1343628

Report Number(s):

SAND2017-1258J
Journal ID: ISSN 1932-7447; 651017

Grant/Contract Number:  

AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 121; Journal Issue: 5; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE