This review of design and operating conditions of electrochemical CO 2reduction covers electrolytes, electrodes, reactors, temperature, pressure, and pH effects.
Electrochemical CO 2reduction (CO 2R) is one of several promising strategies to mitigate CO 2emissions. Electrochemical processes operate at mild conditions, can be tuned to selective products, allow modular design, and provide opportunities to integrate renewable electricity with CO 2reduction in carbon-intensive manufacturing industries such as iron and steel making. In recent years, significant advances have been achieved in the development of highly efficient and selective electrocatalysts for CO 2R. However, to realize fully the potential benefits of new electrocatalysts in low cost, large scale CO 2R electrolyzers requires advances in design and engineering of the CO 2R process. In this review, we examine the state-of-the-art in electrochemical CO 2R technologies, and highlight how the efficiency of CO 2R processes can be improved through (i) electrolyzer configuration, (ii) electrode structure, (iii) electrolyte selection, (iv) pH control, and (v) the electrolyzer's operating pressure and temperature. Although a comprehensive review of catalytic materials is beyond this review's scope, we illustrate how other engineering and design decisions may also influence CO 2R reaction pathways because of effects on mass transfer rates, the electrode surface chemistry, interactions with intermediate reaction species, and rates of charge transfer.