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An electrolysis-cell design for simultaneous electrochemical reduction of and to make syngas at room temperature was developed, based on a technology very close to that of proton-exchange-membrane fuel cells (PEMFC), i.e., based on the use of gas-diffusion electrodes so as to achieve high current densities. While a configuration involving a proton-exchange membrane (Nafion) as electrolyte was shown to be unfavorable for reduction, a modified configuration based on the insertion of a pH-buffer layer (aqueous ) between the silver-based cathode catalyst layer and the Nafion membrane allows for a great enhancement of the cathode selectivity for reduction to CO ca. at a potential of vs SCE (saturated-calomel reference electrode). A ratio of , suitable for methanol synthesis, is obtained at a potential of ca. vs SCE and a total current density of ca. . An issue that has been identified is the change in product selectivity upon long-term electrolysis. Results obtained with two other cell designs are also presented and compared.
Delacourt et al. (Tue,) studied this question.