Electrochemical reduction of carbon dioxide

The electrochemical reduction of carbon dioxide is the conversion of carbon dioxide to more reduced chemical species using electrical energy. It is one possible step in the broad scheme of carbon capture and utilization. The first examples of electrochemical reduction of carbon dioxide are from the 19th century, when carbon dioxide was reduced to carbon monoxide using a zinc cathode. Research in this field intensified in the 1980s following the oil embargoes of the 1970s. Electrochemical reduction of carbon dioxide represents a possible means of producing chemicals or fuels, converting carbon dioxide (CO
2) to organic feedstocks such as formic acid (HCOOH), carbon monoxide (CO), ethylene (C2H4), ethanol (C2H5OH) and methane (CH4).[1][2][3] Among the more selective metallic catalysts in this field are tin for formic acid, gold for carbon monoxide and copper for ethylene, ethanol or methane.

This article is about the electrochemical system. For related systems, see Photoelectrochemical reduction of carbon dioxide and Photochemical reduction of carbon dioxide.

Chemicals from carbon dioxide

In carbon fixation, plants convert carbon dioxide into sugars, from which many biosynthetic pathways originate. The catalyst responsible for this conversion, RuBisCo, is the most common protein on earth. Some anaerobic organisms employ enzymes to convert CO2 to carbon monoxide, from which fatty acids can be made.[4]

In industry, a few products are made from CO2, including urea, salicylic acid, methanol, and certain inorganic and organic carbonates.[5] In the laboratory, carbon dioxide is sometimes used to prepare carboxylic acids. No electrochemical process involving CO2 has been commercialized.

Electrocatalysis

The electrochemical reduction of carbon dioxide to CO is usually described as:

CO2 + 2 H+ + 2 e− → CO + H2O

The redox potential for this reaction is similar to that for hydrogen evolution in aqueous electrolytes, thus electrochemical reduction of CO2 is usually competitive with hydrogen evolution reaction.[3]

Electrochemical methods have gained significant attention: 1) at ambient pressure and room temperature; 2) in connection with renewable energy sources (see also solar fuel) 3) competitive controllability, modularity and scale-up are relatively simple.[6] The electrochemical reduction or electrocatalytic conversion of CO2 can produce value-added chemicals such methane, ethylene, ethane, etc., and the products are mainly dependent on the selected catalysts and operating potentials (applying reduction voltage).[7][8][9]

Although an electrochemical route to CO (or other chemicals) has not been commercialized, a variety of homogeneous and heterogeneous catalysts[10] have been evaluated.[3][1] Many such processes are assumed to operate via the intermediacy of metal carbon dioxide complexes.[11] Generally speaking, the processes developed up to 2010 either had poor thermodynamic efficiency (high overpotential), low current efficiency, low selectivity, slow kinetics, and/or poor stability.[12] In 2011, workers from Dioxide Materials and University of Illinois showed that the combination of two catalysts could eliminate the high overpotential [13] More recently, the same group showed that the process was stable for 6 months at over 90% selectivity.[14] Studies have shown that a gas-diffusion electrode design could promote the reaction rate of electrochemical CO2 reduction to CO and multi-carbon products.[15][16][17]

See also

References
  1. Centi, Gabriele; Perathoner, Siglinda (2009). "Opportunities and prospects in the chemical recycling of carbon dioxide to fuels". Catalysis Today. 148 (3–4): 191–205. doi:10.1016/j.cattod.2009.07.075.
  2. Qiao, J.; et al. (2014). "A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels". Chem. Soc. Rev. 43 (2): 631–675. doi:10.1039/c3cs60323g. PMID 24186433.
  3. Appel, A. M.; et al. (2013). "Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2 Fixation". Chem. Rev. 113 (8): 6621–6658. doi:10.1021/cr300463y. PMC 3895110. PMID 23767781.
  4. Fontecilla-Camps, J. C.; Amara, P.; Cavazza, C.; Nicolet, Y.; Volbeda, A. (2009). "Structure-function relationships of anaerobic gas-processing metalloenzymes". Nature. 460 (7257): 814–822. Bibcode:2009Natur.460..814F. doi:10.1038/nature08299. PMID 19675641.
  5. Susan Topham, "Carbon Dioxide" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_165
  6. Lee, S.; et al. (2016). "Electrode Build-Up of Reducible Metal Composites toward Achievable Electrochemical Conversion of Carbon Dioxide". ChemSusChem. 9 (4): 333–344. doi:10.1002/cssc.201501112. PMID 26610065.
  7. Lee, S.; et al. (2015). "Sustainable production of formic acid by electrolytic reduction of gaseous carbon dioxide". J. Mater. Chem. A. 3 (6): 3029–3034. doi:10.1039/C4TA03893B.
  8. Whipple, D.T.; et al. (2010). "Prospects of CO
    2     Utilization via Direct Heterogeneous Electrochemical Reduction". J. Phys. Chem. Lett. 1 (24): 3451–3458. doi:10.1021/jz1012627.
  9. Machundaa, R.L.; et al. (2011). "Electrocatalytic reduction of CO
    2     gas at Sn-based gas diffusion electrode". Current Applied Physics. 11: 986–988. doi:10.1016/j.cap.2011.01.003.
  10. Hori, Y. (2008). "Electrochemical CO2 Reduction on Metal Electrodes". Modern Aspects of Electrochemistry. Modern Aspects of Electrochemistry. 42. pp. 89–80. doi:10.1007/978-0-387-49489-0_3. ISBN 978-0-387-49488-3.
  11. Benson, Eric E.; Kubiak, Clifford P.; Sathrum, Aaron J.; Smieja, Jonathan M. (2009). "Electrocatalytic and homogeneous approaches to conversion of CO
    2     to liquid fuels". Chem. Soc. Rev. 38 (1): 89–99. doi:10.1039/b804323j. PMID 19088968. S2CID 20705539.
  12. Halmann and Steinberg, "Greenhouse Gas Carbon Dioxide Mitigation," Lewis Publishers, 1999. ISBN 1-56670-284-4
  13. Rosen, Brian A.; Salehi-Khojin, Amin; Thorson, Michael R.; Zhu, W.; Whipple, Devin T.; Kenis, Paul J. A.; Masel, Richard I (2011). "Ionic Liquid-Mediated Selective Conversion of CO2 to CO at Low Overpotentials". Science. 334 (6056): 643–644. Bibcode:2011Sci...334..643R. doi:10.1126/science.1209786. PMID 21960532.
  14. R.F. Service, Two new ways to turn 'garbage’ carbon dioxide into fuel www.sciencemag.org/news/2017/09/two-new-ways-turn-garbage-carbon-dioxide-fuel
  15. Thorson, Michael R.; Siil, Karl I.; Kenis, Paul J. A. (2013). "Effect of Cations on the Electrochemical Conversion of CO 2 to CO". Journal of the Electrochemical Society. 160 (1): F69–F74. doi:10.1149/2.052301jes. ISSN 0013-4651. S2CID 95111100.
  16. Lv, Jing-Jing; Jouny, Matthew; Luc, Wesley; Zhu, Wenlei; Zhu, Jun-Jie; Jiao, Feng (December 2018). "A Highly Porous Copper Electrocatalyst for Carbon Dioxide Reduction". Advanced Materials. 30 (49): 1803111. doi:10.1002/adma.201803111. PMID 30368917.
  17. Dinh, Cao-Thang; Burdyny, Thomas; Kibria, Md Golam; Seifitokaldani, Ali; Gabardo, Christine M.; García de Arquer, F. Pelayo; Kiani, Amirreza; Edwards, Jonathan P.; De Luna, Phil (2018-05-18). "CO 2 electroreduction to ethylene via hydroxide-mediated copper catalysis at an abrupt interface". Science. 360 (6390): 783–787. doi:10.1126/science.aas9100. ISSN 0036-8075. PMID 29773749.
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