%0 Journal Article
%A Charles Delacourt
%A Paul L Ridgway
%A John B Kerr
%A John S Newman
%B Journal of Electrochemical Society
%D 2008
%G eng
%P B42-B49
%R 10.1149/1.2801871
%T Design of an Electrochemical Cell Making Syngas  (CO + H<sub>2</sub>)  from CO<sub>2</sub> and H<sub>2</sub>O Reduction at Room Temperature
%V 155
%8 11/2007
%X <p>An electrolysis-cell design for simultaneous electrochemical reduction of CO<sub>2</sub> and H<sub>2</sub>O to make syngas (CO+H<sub>2</sub>) at room temperature (25C) 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 CO<sub>2</sub> reduction, a modified configuration based on the insertion of a pH-buffer layer (aqueous KHCO<sub>3</sub>) between the silver-based cathode catalyst layer and the Nafion membrane allows for a great enhancement of the cathode selectivity for CO<sub>2</sub> reduction to CO [ca. 30 mA/cm<sup>2</sup> at a potential of -1.7 to 1.75 V vs SCE (saturated-calomel reference electrode)]. A CO/H<sub>2</sub> ratio of 1/2, suitable for methanol synthesis, is obtained at a potential of ca. -2 V vs SCE and a total current density of ca. 80mA/cm<sup>2</sup> . 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.</p>