Bifunctional Gas Diffusion Electrode Enables In Situ Separation and Conversion of CO₂ to Ethylene from Dilute Stream

Abstract

The requirement of concentrated carbon dioxide (CO2) feedstock significantly limits the economic feasibility of electrochemical CO2 reduction (eCO2R) which often involves multiple intermediate processes, including CO2 capture, energy‐intensive regeneration, compression, and transportation. Herein, a bifunctional gas diffusion electrode (BGDE) for separation and eCO2R from a low‐concentration CO2 stream is reported. The BGDE is demonstrated for the selective production of ethylene (C2H4) by combining high‐density‐polyethylene‐derived porous carbon (HPC) as a physisorbent with polycrystalline copper as a conversion catalyst. The BGDE shows substantial tolerance to 10 vol% CO2 exhibiting a Faradaic efficiency of ≈45% toward C2H4 at a current density of 80 mA cm−2, outperforming previous reports that utilized such partial pressure (PCO2 = 0.1 atm and above) and unaltered polycrystalline copper. Molecular dynamics simulation and mixed gas permeability assessment reveal that such selective performance is ensured by high CO2 uptake of the microporous HPC as well as continuous desorption owing to the molecular diffusion and concentration gradient created by the binary flow of CO2 and nitrogen (CO2|N2) within the sorbent boundary. Based on detailed techno‐economic analysis, it is concluded that this in situ process can be economically compelling by precluding the C2H4 production cost associated with the energy‐intensive intermediate steps of the conventional decoupled process.

Solid Electrolytes for Low-Temperature Carbon Dioxide Valorization: A Review

“…(d) Bifunctional GDE, which consisted of both solid sorbent and electrocatalyst, to increase the local CO 2 concentration. Adapted with permission from ref (copyright 2023 Wiley-VCH ). (e) Microbial electromethanogenesis powered by an intermittent excess of renewable energy.…”

“…A film of nitrile-modified metal–organic framework (MOF) could serve to preconcentrate and activate CO 2 before its electroreduction . Moreover, the utilization of a bifunctional GDE that incorporates both a solid sorbent and an electrocatalyst can greatly enhance the local concentration of CO 2 , resulting in the promotion of CO 2 RR (Figure d) . These bifunctional GDE can be fabricated by sandwiching or coating a MOF-induced organic layer and modifying the backside of the gas diffusion layer (GDL) with polyethylene-derived porous carbon …”

“…135 Moreover, the utilization of a bifunctional GDE that incorporates both a solid sorbent and an electrocatalyst can greatly enhance the local concentration of CO 2 , resulting in the promotion of CO 2 RR (Figure 5d). 136 layer 137 and modifying the backside of the gas diffusion layer (GDL) with polyethylene-derived porous carbon. 136 4.3.…”

Efficient electrolysis of CO2 capture solution to syngas over Ni‐N‐C catalyst

“…Carbon capture and utilization (CCU) technologies offer a promising solution to address the challenges of CO 2 utilization 6,7 . Coupling of alkaline solution‐mediated CO 2 uptake with renewable electricity‐driven electrocatalytic CO 2 conversion shows more promise than the more well‐established amine solution‐mediated CO 2 capture and thermos‐catalytic CO 2 resource recovery processes 8,9 . Electrocatalytic CO 2 reduction (CO 2 R) processes offer a promising approach for implementing strategies aimed at reducing CO 2 10–12 .…”

“…Direct electrochemical conversion of CO 2 capture solution presents a promising approach for CO 2 treatment, obviating the need for energy‐intensive processes such as CO 2 enrichment and compression (Figure S1), 9,19,20 effectively reducing the energy consumption of CO 2 utilization 21,22 . Moreover, it is more economically feasible than both alkaline flow cells and direct gas feed reactor (Supporting note 1).…”