Durable Cathodes and Electrolyzers for the Efficient Aqueous Electrochemical Reduction of CO₂

Abstract

The world emits over 14 gigatons of CO2 in excess of what can be remediated by natural processes annually, contributing to rising atmospheric CO2 levels and increasing global temperatures. The electrochemical reduction of CO2 (CO2RR) to value‐added chemicals and fuels has been proposed as a method for reusing these excess anthropogenic emissions. While state‐of‐the‐art CO2RR systems exhibit high current densities and faradaic efficiencies, research on long‐term electrode durability, necessary for this technology to be implemented commercially, is lacking. Previous reviews have focused mainly on the CO2 electrolyzer performance without considering durability. In this Review, the need for research into high‐performing and durable CO2RR systems is stressed by summarizing the state‐of‐the‐art with respect to durability. Various failure modes observed are also reported and a protocol for standard durability testing of CO2RR systems is proposed.

Highly Efficient Electroreduction of CO2 to C2+ Alcohols on Heterogeneous Dual Active Sites

“…It can not only reduce the CO 2 concentration in the environment, but also can facilitate the storage of renewable energy on a large scale. [1][2][3][4][5] In recent years, various valuable products have been obtained, and the C2 + products are more attractive owing to their high energy densities and high economic value per unit mass. [6][7][8][9][10] Among the various C2 + products, alcohols (such as ethanol and npropanol) are highly desirable, which can be either used directly as a fuel or blended with gasoline to give an overall cleaner-burning fuel.…”

Three-Dimensional Cathodes for Electrochemical Reduction of CO2: From Macro- to Nano-Engineering

“…Table 1. Selected products and equilibrium potentials of electrochemical reduction of CO 2 [16] (this table is To date, electrochemical reduction of CO 2 has been demonstrated by systems operating under ambient conditions (H-cell, flow cells, membrane-electrode-assembly (MEA) cells) or under high temperatures such as solid oxide electrolysis cells (SOECs) [17][18][19][20]. Figure 1 illustrates configurations of different reactor designs commonly used for the electrochemical reduction of CO 2 [19].…”

“…The main selectivity issue is competitive water reduction to produce H 2 , i.e., hydrogen evolution reaction (HER). One effective approach to restrict HER is using strong alkaline electrolyte; another is to engineer an electrocatalyst to not favor HER [17]. Catalysts do not just reduce the energy barrier, but may also promote a completely different reaction pathway typically with multiple energy barriers that must be overcome and then lead to the change of product selectivity of CO 2 reduction.…”

“…However, their long-term durability has not been extensively studied yet. Several failure modes have been identified, such as formation and blockage of bubbles and carbonate precipitation on the electrode surface [17,19]. At the component level, there are several concerns, including catalyst degradation due to agglomeration and poisoning, electrode failures from anode oxidation and instability of layered cathodes based on GDL, and electrolyte changes of composition and pH [17].…”

In situ study of surface species and structure over Oxide-Derived Copper Catalysts for Electrochemical CO2 Reduction

“…Electrochemical CO 2 reduction reaction (CO 2 RR) has received wide attention, which can not only reduce CO 2 into chemical fuels and feedstocks, but also provide an energy storage solution to the renewable energy sources. [1][2][3][4][5] Especially, multi-carbon (C2+) products are much more attractive, due to the high energy density and high economic value. [6][7][8][9][10] However, the activity and selectivity for C2+ products are severely limited by slow kinetics of C-C coupling step, which involves intricate multiple proton and electron transfer.…”