Method for modifying electrocatalyst material, electrochemical cells and electrodes containing this modified material, and synthesis methods utilizing the cells

US4818353A · kind A · utility

Inventors

• Stanley H. Langer · Madison, US
• Michael J. Foral · Aurora, US
• John Card · Big Rapids, US

Key dates

• Filing date: Jul 7, 1987
• Grant date: Apr 4, 1989
• Expiry date: Jul 7, 2007

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S204/04
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A transition metal electrocatalyst surface (e.g. a porous surface of finely divided Group VIII or Group I-B metal with an attached current collector) is modified by a sulfur treatment, using an oxidized sulfur species of average sulfur oxidation state of about 4 or less, e.g. SO.sub.2 dissolved in aqueous acid. Treatment of the transition metal with SO.sub.2 or the like typically provides up to 100% coverage of the surface electrocatalyst sites with chemisorbed sulfur-containing species and perhaps subsurface effects as well, but washing or other non-electrochemical techniques can remove 5-90% (e.g. 25-70%) of the chemisorbed SO.sub.2 or the like from the surface, leaving substantially only a very strongly bound form of the sulfur-containing species. The strongly bound sulfur-containing species can then be reduced to form a highly beneficial, selectively-improving pattern of sites containing reduced -S (e.g. sulfur or sulfide) on the electrocatalyst surface. Electrochemical synthesis cells can be constructed from a cathode and/or anode made form the S-treated electrocatalyst This invention was made with United States Government support awarded by the National Sciences Foundation (N…