skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Copper Silver Thin Films with Metastable Miscibility for Oxygen Reduction Electrocatalysis in Alkaline Electrolytes

Abstract

Increasing the activity of Ag-based catalysts for the oxygen reduction reaction (ORR) is important for improving the performance and economic outlook of alkaline-based fuel cell and metal-air battery technologies. In this work, we prepare CuAg thin films with controllable compositions using e-beam physical vapour deposition. X-ray diffraction analysis indicates that this fabrication route yields metastable miscibility between these two thermodynamically immiscible metals, with the thin films consisting of a Ag-rich and a Cu-rich phase. Electrochemical testing in 0.1 M potassium hydroxide showed significant ORR activity improvements for the CuAg films. On a geometric basis, the most active thin film (Cu 70Ag 30) demonstrated a 4-fold activity improvement versus pure Ag at 0.8 V vs the reversible hydrogen electrode. Furthermore, enhanced ORR kinetics for Cu-rich (> 50at % Cu) thin films was demonstrated by a decrease in Tafel slope from 90 mV/dec, a commonly observed value for Ag catalysts, to 45 mV/dec. Surface enrichment of the Ag-rich phase after ORR testing was indicated by x-ray photoelectron spectroscopy and grazing incidence synchrotron x-ray diffraction measurements. Here, by correlating density functional theory with experimental measurements, we postulate that the activity enhancement of the Cu-rich CuAg thin films arises due to the non-equilibrium miscibilitymore » of Cu atoms in the Ag-rich phase, which favourably tunes the surface electronic structure and binding energies of reaction species.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [1]; ORCiD logo [1];  [4];  [5];  [1];  [6]; ORCiD logo [6];  [2];  [1]; ORCiD logo [1]
  1. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Stanford Univ., Stanford, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
  4. Stanford Univ., Stanford, CA (United States); Univ. of Copenhagen, Copenhagen (Denmark)
  5. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Trinity College Dublin, Dublin (Ireland)
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1459655
Grant/Contract Number:  
SC0008685; AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Energy Materials
Additional Journal Information:
Journal Volume: 1; Journal Issue: 5; Journal ID: ISSN 2574-0962
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; chloroalkali process; electrocatalysis; electrochemistry; fuel cells; oxygen reduction; physical vapor deposition; sustainable energy; thin films

Citation Formats

Higgins, Drew, Wette, Melissa, Gibbons, Brenna M., Siahrostami, Samira, Hahn, Christopher, Escudero-Escribano, Mar?ia, Garcia-Melchor, Max, Ulissi, Zachary, Davis, Ryan C., Mehta, Apurva, Clemens, Bruce M., Norskov, Jens K., and Jaramillo, Thomas F. Copper Silver Thin Films with Metastable Miscibility for Oxygen Reduction Electrocatalysis in Alkaline Electrolytes. United States: N. p., 2018. Web. doi:10.1021/acsaem.8b00090.
Higgins, Drew, Wette, Melissa, Gibbons, Brenna M., Siahrostami, Samira, Hahn, Christopher, Escudero-Escribano, Mar?ia, Garcia-Melchor, Max, Ulissi, Zachary, Davis, Ryan C., Mehta, Apurva, Clemens, Bruce M., Norskov, Jens K., & Jaramillo, Thomas F. Copper Silver Thin Films with Metastable Miscibility for Oxygen Reduction Electrocatalysis in Alkaline Electrolytes. United States. doi:10.1021/acsaem.8b00090.
Higgins, Drew, Wette, Melissa, Gibbons, Brenna M., Siahrostami, Samira, Hahn, Christopher, Escudero-Escribano, Mar?ia, Garcia-Melchor, Max, Ulissi, Zachary, Davis, Ryan C., Mehta, Apurva, Clemens, Bruce M., Norskov, Jens K., and Jaramillo, Thomas F. Mon . "Copper Silver Thin Films with Metastable Miscibility for Oxygen Reduction Electrocatalysis in Alkaline Electrolytes". United States. doi:10.1021/acsaem.8b00090.
@article{osti_1459655,
title = {Copper Silver Thin Films with Metastable Miscibility for Oxygen Reduction Electrocatalysis in Alkaline Electrolytes},
author = {Higgins, Drew and Wette, Melissa and Gibbons, Brenna M. and Siahrostami, Samira and Hahn, Christopher and Escudero-Escribano, Mar?ia and Garcia-Melchor, Max and Ulissi, Zachary and Davis, Ryan C. and Mehta, Apurva and Clemens, Bruce M. and Norskov, Jens K. and Jaramillo, Thomas F.},
abstractNote = {Increasing the activity of Ag-based catalysts for the oxygen reduction reaction (ORR) is important for improving the performance and economic outlook of alkaline-based fuel cell and metal-air battery technologies. In this work, we prepare CuAg thin films with controllable compositions using e-beam physical vapour deposition. X-ray diffraction analysis indicates that this fabrication route yields metastable miscibility between these two thermodynamically immiscible metals, with the thin films consisting of a Ag-rich and a Cu-rich phase. Electrochemical testing in 0.1 M potassium hydroxide showed significant ORR activity improvements for the CuAg films. On a geometric basis, the most active thin film (Cu70Ag30) demonstrated a 4-fold activity improvement versus pure Ag at 0.8 V vs the reversible hydrogen electrode. Furthermore, enhanced ORR kinetics for Cu-rich (> 50at % Cu) thin films was demonstrated by a decrease in Tafel slope from 90 mV/dec, a commonly observed value for Ag catalysts, to 45 mV/dec. Surface enrichment of the Ag-rich phase after ORR testing was indicated by x-ray photoelectron spectroscopy and grazing incidence synchrotron x-ray diffraction measurements. Here, by correlating density functional theory with experimental measurements, we postulate that the activity enhancement of the Cu-rich CuAg thin films arises due to the non-equilibrium miscibility of Cu atoms in the Ag-rich phase, which favourably tunes the surface electronic structure and binding energies of reaction species.},
doi = {10.1021/acsaem.8b00090},
journal = {ACS Applied Energy Materials},
number = 5,
volume = 1,
place = {United States},
year = {Mon May 07 00:00:00 EDT 2018},
month = {Mon May 07 00:00:00 EDT 2018}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 7, 2019
Publisher's Version of Record

Save / Share: