Copper silver thin films with metastable miscibility for oxygen reduction electrocatalysis in alkaline electrolytes
File Type:
UnknownItem Type:
Journal ArticleDate:
2018Author:
Access:
openAccessCitation:
Higgins, D.; Wette, M.; Gibbons, B. M.; Siahrostami, S.; Hahn, C.; Escudero-Escribano, M.; García-Melchor, M.; Ulissi, Z.; Davis, R. C.; Mehta, A.; Clemens, B. M.; Nørskov, J. K.; Jaramillo, T. F., Copper silver thin films with metastable miscibility for oxygen reduction electrocatalysis in alkaline electrolytes, ACS Appl. Energy Mater., 1, 2018, 1990 - 1999Download Item:
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 electron beam physical vapor 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 vs pure Ag at 0.8 V vs the reversible hydrogen electrode. Furthermore, enhanced ORR kinetics for Cu-rich (>50 at. % 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. 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 favorably tunes the surface electronic structure and binding energies of reaction species.
Author's Homepage:
http://people.tcd.ie/garciammDescription:
PUBLISHED
Author: Garcia Melchor, Max
Type of material:
Journal ArticleCollections
Series/Report no:
ACS Appl. Energy Mater.1
Availability:
Full text availableKeywords:
Electrocatalysis, Oxygen reduction, Fuel cells, Sustainable energy, Chloroalkali process, Physical vapor deposition, Electrochemistry, Thin filmsDOI:
https://doi.org/10.1021/acsaem.8b00090Metadata
Show full item recordLicences: