The Technical and Energetic Challenges of Separating (Photo)Electrochemical Carbon Dioxide Reduction Products

What Should We Make with CO2 and How Can We Make It?

“…7 The costs for separation of products from a catalyst with poor selectivity, despite high activity, make this prohibitively uncompetitive. 17 Unless a method is developed to produce higher-carbon products selectively and with extraordinarily high FEs, it would be more economical to focus on producing useful building blocks (methanol, CO, ethylene, aldehydes) that can be upgraded in further chemical or electrochemical processes, 18 such as the Fischer-Tropsch or methanol to olefin process. 19 ( Figure 1B) These technologies can be applied to upgrade the building-block renewable chemicals to long-chain hydrocarbons for direct replacements of gasoline, diesel, or jet fuels.…”

Strategies in catalysts and electrolyzer design for electrochemical CO 2 reduction toward C 2+ products

“…C 2+ hydrocarbons, such as C 2 H 4 , are nexus chemicals for a variety of chemical industries, such as polyethylene production (62,63). Besides, it could be directly used as the fuel for welding or a mixed component in natural gas (12). Hydrogenation of CO (Fischer-Tropsch synthesis) and CO 2 has been used to produce C 2+ hydrocarbons for a long time in industrial scale but challenged by high energy consumption and environmental impact (64).…”

“…However, the fraction of energy from those renewable sources is only limited to 30% owing to their intermittent nature, unless approaches for largescale energy storage become available (9). Hence, as an alternative, capture of CO 2 from point sources such as power plants, followed by conversion into chemical feedstocks and fuels, is more practically viable (9)(10)(11)(12). Electrocatalytic CO 2 reduction (ECR) using renewable electricity represents an elegant long-term solution due to the mild operation conditions required for the conversions, in which valueadded products could be selectively produced (13).…”

Gas-Diffusion Electrodes for Carbon Dioxide Reduction: A New Paradigm

“…For example, when targeting alcohol products, in comparison to aqueous-phase CO 2 R, vapor-fed devices will avoid the formation of azeotropic alcohol/water mixtures that would require energy intensive downstream separation processes. 21 Clearly there is an immense opportunity for the development of solid polymer electrolytes and their integration with vapor-fed CO 2 R GDEs. Key challenges include designing and integrating new polymer electrolytes that simultaneously satisfy the requirements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 8 of low cost, high ionic conductivity and selectivity, resistance to reactant/product crossover, CO 2 tolerance, and long-term chemical and mechanical stability under operating conditions.…”