title: Systematic Analysis of Electrochemical CO₂ Reduction with Various Reaction Parameters using Combinatorial Reactors.
abstract: Applying combinatorial technology to electrochemical CO2 reduction offers a broad range of possibilities for optimizing the reaction conditions. In this work, the CO2 pressure, stirring speed, and reaction temperature were varied to investigate the effect on the rate of CO2 supply to copper electrode and the associated effects on reaction products, including CH4. Experiments were performed in a 0.5 M KCl solution using a combinatorial screening reactor system consisting of eight identical, automatically controlled reactors. Increasing the CO2 pressure and stirring speed, or decreasing the temperature, steadily suppressed H2 production and increased the production of other reaction products including CH4 across a broad range of current densities. Our analysis shows that the CO2 pressure, stirring speed, and reaction temperature independently contributed to the limiting rate of CO2 supply to the electrode (Jlim). At a constant temperature, the limiting current density of CH4 increased proportionally with Jlim, illustrating that the production rate of CH4 was proportional to CO2 supply. Varying the CO2 pressure and stirring speed hardly affected the maximum Faradaic efficiency of CH4 production. However, changes to the reaction temperature showed a significant contribution to CH4 selectivity. This study highlights the importance of quantitative analysis of CO2 supply in clarifying the role of various reaction parameters and understanding more comprehensively the selectivity and reaction rate of electrochemical CO2 reduction.
authors.affiliation: Advanced Research Division, Panasonic Corporation , So̅raku-gun, Kyoto 619-0237, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashiba
authors.affiliation: Advanced Research Division, Panasonic Corporation , So̅raku-gun, Kyoto 619-0237, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yotsuhashi
authors.affiliation: Advanced Research Division, Panasonic Corporation , So̅raku-gun, Kyoto 619-0237, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Deguchi
authors.affiliation: Advanced Research Division, Panasonic Corporation , So̅raku-gun, Kyoto 619-0237, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques / Q000295:instrumentation; D003300:Copper / Q000737:chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation; D004566:Electrodes; D008697:Methane / Q000138:chemical synthesis / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: D002245:Carbon Dioxide; D003300:Copper; D008697:Methane
keywords: CO2 reduction; combinatorial screening; copper; electrochemistry; methane production