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

摘要

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. SO2 dissolved in aqueous acid. Treatment of the transition metal with SO2 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 SO2 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 and used in highly selective syntheses of useful organic and inorganic compounds from various starting materials, e.g. by reduction of O2 to H2O2, reduction of NO to NH2OH, oxidation of RCH2OH to RCOOCH2R (R=lower alkyl, etc.), oxidation of RR'CHOH to RCOR' (R and R'=lower alkyl, etc.) or the like.