Reactor design and integration with product detection to accelerate screening of electrocatalysts for carbon dioxide reduction

Abstract

Identifying new catalyst materials for complex reactions such as the electrochemical reduction of CO 2 poses substantial instrumentation challenges due to the need to integrate reactor control with electrochemical and analytical instrumentation. Performing accelerated screening to enable exploration of a broad span of catalyst materials poses additional challenges due to the long time scales associated with accumulation of reaction products and the detection of the reaction products with traditional separation-based analytical methods. The catalyst screening techniques that have been reported for combinatorial studies of (photo)electrocatalysts do not meet the needs of CO 2 reduction catalyst research, prompting our development of a new electrochemical cell design and its integration to gas and liquid chromatography instruments. To enable rapid chromatography measurements while maintaining sensitivity to minor products, the electrochemical cell features low electrolyte and head space volumes compared to the catalyst surface area. Additionally, the cell is operated as a batch reactor with electrolyte recirculation to rapidly concentrate reaction products, which serves the present needs for rapidly detecting minor products and has additional implications for enabling product separations in industrial CO 2 electrolysis systems. To maintain near-saturation of CO 2 in aqueous electrolytes, we employ electrolyte nebulization through a CO 2 -rich headspace, achieving similar gas-liquid equilibration as vigorous CO 2 bubbling but without gas flow. The instrument is demonstrated with a series of electrochemical experiments on an Au-Pd combinatorial library, revealing non-monotonic variations in product distribution with respect to catalyst composition. The highly integrated analytical electrochemistry system is engineered to enable automation for rapid catalyst screening as well as deployment for a broad range of electrochemical reactions where product distribution is critical to the assessment of catalyst performance. Published by AIP Publishing. https://doi.

Recent Trends, Benchmarking, and Challenges of Electrochemical Reduction of CO2 by Molecular Catalysts

“…These flow cell reactors are more relevant than the typical H‐cell on a commercial scale (>200 mA cm −2 ), to screen and employ the best catalytic system. Weekes et al provide a detailed account on the advantages of the flow cells over H‐cells in addition to comparing the membrane arrangement and the microfluidic reactor configuration; while, Jones et al report effective techniques to integrate these reactors to product detection methods which can effectively accelerate not only the identification of the best catalytic system but also an optimal reactor design. Furthermore, the development of the flow reactors with PEMs for CO 2 reduction can greatly benefit from the well‐established PEM fuel cell technologies.…”

“…Weekes et al [130] provide a detailed account on the advantages of the flow cells over H-cells in addition to comparing the membrane arrangement and the microfluidic reactor configuration; while, Jones et al [131] report effective techniques to integrate these reactors to product detection methods which Adv. In addition, the intrinsic conductivity of the pure MOFs electrocatalyst prominently affects the electrocatalytic activity, mass transport, and charge propagation during the reaction.…”

Breaking Scaling Relationships in CO2 Reduction on Copper Alloys with Organic Additives

“…Our development of high-throughput electrochemistry coupled to an automated product distribution analysis provides new opportunities for identifying scaling relationships. 9 , 10 Herein, we demonstrate a combination of catalyst design, high-throughput experimentation, and data science as a paradigm shift in both the identification of scaling relationships and the discovery of strategies for breaking them. We focus on applying this approach to CO 2 reduction (CO 2 R) on Cu-based electrodes, an area where mechanistic complexity has obscured the identification of scaling relationships, has hindered catalyst optimization, and warrants further investigation.…”

Breaking Scaling Relationships in CO2 Reduction on Copper Alloys with Organic Additives

“…We have developed a high throughput screening system for accelerated catalyst discovery whose improved automation and operation make it particularly well suited for this application. 28,29 We have identified bulk alloying of Cu as an underdeveloped, though promising strategy for catalyst optimization, with a large parameter space available based on the metal identity and composition. 30,31 Additionally, organic additives represent an attractive orthogonal parameter of catalyst design.…”