{ "id": "ep2ws4nxxt", "slug": "electrocatalytic-carbon-dioxide-reduction", "title": "Electrocatalytic carbon dioxide reduction", "updated": "2026-10-15", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods" }, { "id": "physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis" }, { "id": "physical.chemistry.methods.chemical-synthesis.energy-assisted-synthesis", "label": "Sonochemical and energy-assisted synthesis", "api_url": 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"https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods.chemical-synthesis" } ] } ], "excerpt": "Electrocatalytic carbon dioxide reduction (CO2RR) is an electrochemistry method that uses electric current and a catalyst to convert CO2 into chemicals such as ethylene and ethanol.", "snippet": "Electrocatalytic carbon dioxide reduction (CO2RR) is an electrochemistry method that uses electric current and a catalyst to convert CO2 into chemicals such as ethylene and ethanol.", "node": "physical.chemistry.methods.chemical-synthesis.energy-assisted-synthesis", "markdown": "# Electrocatalytic carbon dioxide reduction\n\nElectrocatalytic carbon dioxide reduction (CO2RR) is an electrochemistry method that uses electric current and a catalyst surface to convert CO2 into value-added chemicals such as carbon monoxide, formate, methane, methanol, ethylene, ethanol, acetate, and 1-propanol.[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) Because the electricity can come from intermittent renewable sources, the method is pursued both for carbon utilization and for storing renewable energy in chemical bonds.[2](https://www.sciencedirect.com/science/article/abs/pii/S2211339813000294) Up to 16 different CO2-based compounds, including glyoxal, ethylene glycol, and acetaldehyde, have been reported, mostly as trace amounts.[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf)\n\n| Key fact | Value |\n|---|---|\n| Main products | CO, formate, methane, methanol, ethylene, ethanol, acetate, 1-propanol[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) |\n| Standard potentials vs SHE | CO2/CO −0.106 V; CO2/HCOOH −0.250 V; CO2/CH3OH +0.016 V; CO2/CH4 +0.169 V; CO2/C2H4 +0.064 V[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf) |\n| One-electron barrier | CO2/CO2·− at \\( E_{0} \\) = −1.90 V vs NHE[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) |\n| CO2 solubility in water | ≈33 mM at ambient conditions[4](https://doi.org/10.1016/j.xcrp.2026.103415) |\n| Best CO/formate selectivity | >99% at >200 mA cm−2[5](https://link.springer.com/article/10.1007/s43979-024-00106-7) |\n| Best C2+ selectivity | 91 ± 2% C2+ FE, 73 ± 2% ethylene FE at 150 mA cm−2 (Zn–Cu)[6](https://www.nature.com/articles/s41467-023-36926-x) |\n| Industrial maturity | Pilot scale only, except commercial solid oxide electrolyzers[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf) |\n\n## How it works\n\nCO2 is a highly stable, linear molecule with a standard [Gibbs free energy](https://www.edgepedia.org/gibbs-free-energy) of formation of −394.4 kJ mol−1, so its reduction under ambient conditions is thermodynamically demanding.[4](https://doi.org/10.1016/j.xcrp.2026.103415) The direct outer-sphere one-electron step to the radical anion CO2·− requires \\( E_{0} \\) = −1.90 V vs NHE because the linear molecule must bend; a catalyst avoids this cost by binding CO2 and stabilizing proton-coupled intermediates such as *COOH and *CO.[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477)\n\nThe cathode half-reactions are proton-coupled electron transfers:[2](https://www.sciencedirect.com/science/article/abs/pii/S2211339813000294)\n\n\\[ \\mathrm{CO_2 + 2H^+ + 2e^- \\rightarrow CO + H_2O} \\]\n\\[ \\mathrm{CO_2 + H^+ + 2e^- \\rightarrow HCOO^-} \\]\n\\[ \\mathrm{CO_2 + 8H^+ + 8e^- \\rightarrow CH_4 + 2H_2O} \\]\n\\[ \\mathrm{2CO_2 + 12H^+ + 12e^- \\rightarrow C_2H_4 + 4H_2O} \\]\n\nAlthough CO formation has an \\( E_{0} \\) of −0.10 V and C2H4 an \\( E_{0} \\) of +0.08 V vs RHE, ethylene emerges only at much more negative potentials because its formation requires 12 electrons.[4](https://doi.org/10.1016/j.xcrp.2026.103415) The hydrogen evolution reaction (\\( E_{0} \\) = 0 V vs RHE) competes with all of these near-zero-potential reactions, so suppressing HER is a central design problem.[7](https://oar.a-star.edu.sg/storage/p/prrv01jqde/chem-eng-j-472-2023-145033-oar.pdf) On copper, adsorbed *CO is further hydrogenated through *CHO, *CH2O, and *CH3O to methane; *CH2O can desorb as formaldehyde and *CH3O can hydrogenate to methanol.[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC11134526/) C–C coupling between CO*, CHO*, or COH* intermediates is a thermochemical rate-determining step that surface polarization does not directly accelerate.[6](https://www.nature.com/articles/s41467-023-36926-x)\n\n## How it is done\n\nPractitioners choose among three cell families. Classical H-cells hold the catalyst in CO2-saturated electrolyte; the low CO2 concentration in water (about 30 mM) causes mass-transport limitations and current densities below 50 mA cm−2.[9](https://pubs.rsc.org/en/content/articlepdf/2025/ey/d5ey00047e) Flow cells supply CO2 as a gas through a gas diffusion electrode, which shortens the CO2 diffusion layer from about 50 μm in liquid feed to about 50 nm near the catalyst, enabling higher current density at lower overpotential.[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf) [Membrane electrode assembly](https://www.edgepedia.org/membrane-electrode-assembly) (MEA) electrolyzers press the gas diffusion electrode against an ion-exchange membrane, eliminating carbonate fouling of the catalyst and electrolyte flooding through the GDE.[10](https://doi.org/10.1016/j.joule.2019.07.021)\n\nElectrolyte choice is a trade-off: strongly alkaline media support high geometric current densities but inevitably form carbonates and bicarbonates from CO2 reacting with OH−, while acidic media promote competing H2 production.[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) [Performance](https://www.edgepedia.org/performance) is quantified by the Faradaic efficiency,\n\n\\[ \\varepsilon_{\\mathrm{Faradaic}} = \\frac{z \\cdot n \\cdot F}{Q} \\]\n\nwhere z is the number of electrons required for the product, n the moles of product formed, F the [Faraday constant](https://www.edgepedia.org/faraday-constant) (96,485 C/mol), and Q the total charge passed.[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf)\n\n## Origin\n\nYoshio Hori, Akira Murata, and Ryutaro Takahashi reported in 1989, in the Journal of the Chemical Society, Faraday Transactions 1, that at a copper electrode in aqueous solution, CO, CH4, C2H4, ethanol, and n-propanol are produced from CO2 at ambient temperatures.[11](https://doi.org/10.1039/f19898502309) CO formation predominates at potentials more positive than −1.2 V vs NHE, while hydrocarbons and alcohols form below −1.3 V vs NHE.[11](https://doi.org/10.1039/f19898502309) This copper work founded the modern field: more than 40 years later, Cu remains the only metallic element known to reproducibly and efficiently catalyze C2+ formation with practical selectivity at a good rate.[12](https://pubs.rsc.org/be/content/articlehtml/2026/sc/d5sc08419a?page=search) Later work identified 16 products on copper, with CH4 and C2H4 carrying the highest partial current densities.[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) Formate catalysts evolved from lead electrodes examined in aqueous medium between 2008 and 2010, to tin electrodes mostly studied between 2011 and 2014, to shape-controlled bismuth nanoflakes used by Kim et al. in 2017.[13](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/celc.202100438) C2+ production in an MEA cell using an anion exchange membrane was reported, reaching 78% FE for C2+ at 200 mA cm−2 with Cu nanoparticles and KHCO3 anolyte.[12](https://pubs.rsc.org/be/content/articlehtml/2026/sc/d5sc08419a?page=search)\n\n## Variants\n\nSelectivity follows how strongly a metal binds *CO. Platinum and nickel bind *CO strongly, causing sluggish CO desorption, CO poisoning, and HER promotion. Tin, indium, and bismuth bind *CO negligibly and yield formic acid. Gold, silver, and zinc bind *CO weakly and yield CO. Copper alone has optimal *CO binding that enables C–C coupled products.[1](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477) Bismuth-based materials show excellent selectivity, efficiency, and long-term stability for formate.[14](https://pmc.ncbi.nlm.nih.gov/articles/PMC12456378/) Modified coppers push C2+ further: a fluorine-modified copper catalyst reached 1.6 A cm−2 with 80% C2+ Faradaic efficiency, mainly ethylene and ethanol, in a flow cell, because fluorine enhances water activation, CO adsorption, and hydrogenation of adsorbed CO to a CHO intermediate that couples readily.[15](https://www.nature.com/articles/s41929-020-0450-0) A zinc-doped Cu2O precatalyst in a porous solid electrolyte reactor delivered over 40% ethanol Faradaic efficiency at 350 mA cm−2.[16](https://www.osti.gov/pages/servlets/purl/2502105)\n\n## Applications\n\nExisting technology achieves over 200 mA cm−2 and >99% selectivity for CO and formic acid production.[5](https://link.springer.com/article/10.1007/s43979-024-00106-7) For C2+, Zn-incorporated copper with asymmetric CO* binding reached 91 ± 2% C2+ FE, 73 ± 2% ethylene FE, and 31 ± 2% full-cell C2+ energy efficiency at 150 mA cm−2 over 150 h, and in a mild-acid pH 4 electrolyte achieved 31 ± 2% single-pass CO2-to-C2+ yield with >80% single-pass CO2 utilization.[6](https://www.nature.com/articles/s41467-023-36926-x) MEA engineering has advanced: a pure-water-fed bipolar-type MEA ran over 1000 h at 333 mA cm−2 with 50% FE for ethylene, and recent AEM-based reports use cell voltages of about 3 to 4 V.[12](https://pubs.rsc.org/be/content/articlehtml/2026/sc/d5sc08419a?page=search) Tandem designs that first reduce CO2 to CO and then reduce CO avoid carbonate formation because CO does not react with OH−; a techno-economic benchmarking analysis found this tandem route with solid oxide electrolyzer CO production the most economically promising for ethylene.[9](https://pubs.rsc.org/en/content/articlepdf/2025/ey/d5ey00047e)\n\n## Limitations and alternatives\n\nCompeting hydrogen evolution, high overpotential, slow kinetics, low stability, and insufficient C2+ selectivity are the primary limitations of state-of-the-art catalysts, and commercialization is further impeded by the lack of appropriate cathode materials and high product separation cost.[17](https://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.5c03120) CO2 solubility in water, about 33 mM, caps H-cell current density.[4](https://doi.org/10.1016/j.xcrp.2026.103415) In alkaline electrolytes, carbonate formation and CO2 crossover can cut theoretical overall carbon efficiency to 25% for ethylene or ethanol and 36% for acetate; in non-zero-gap designs more than 75% of fed CO2 can be lost to carbonate, and electrolyte regeneration adds $0.2–0.3 kg−1 to product cost.[4](https://doi.org/10.1016/j.xcrp.2026.103415) Separation is hard in its own right: CO2 forms an azeotrope with ethylene, so cryogenic distillation cannot purify the product, and CO/ethylene separation is difficult because of their similar [kinetic diameters](https://www.edgepedia.org/kinetic-diameter).[18](https://omoultosethtudelft.github.io/web/assets/publications/64.Ramdin_IECR_2021_60_17862.pdf) Dilute CO2 streams lower CO2 surface coverage and shift the mechanism from C2+ products toward methane, so industrial feeds require purification.[18](https://omoultosethtudelft.github.io/web/assets/publications/64.Ramdin_IECR_2021_60_17862.pdf)\n\nAgainst alternatives, thermocatalytic CO2 hydrogenation is easier to scale to industrial application but is limited by kinetics or thermodynamic equilibrium; electrocatalysis is less mature but runs at low temperature and pressure, uses water as the hydrogen source, and is not restricted by equilibrium.[7](https://oar.a-star.edu.sg/storage/p/prrv01jqde/chem-eng-j-472-2023-145033-oar.pdf) Techno-economic analyses require >80% selectivity and about 50% energy efficiency for a positive net present value.[6](https://www.nature.com/articles/s41467-023-36926-x) On deployment, CO2 electrolysers remain at pilot scale except for solid oxide electrolyzers, used commercially by Haldor Topsoe and under construction at Shell; Haldor Topsoe's commercialized solid oxide cell converts CO2 to CO with a claimed energy requirement of 6–8 kWh/Nm3 CO.[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf) • [18](https://omoultosethtudelft.github.io/web/assets/publications/64.Ramdin_IECR_2021_60_17862.pdf) Published industrial targets differ: one analysis sets >300 mA cm−2, >80% selectivity, cell voltage below 1.8 V, and stability exceeding 80,000 h,[5](https://link.springer.com/article/10.1007/s43979-024-00106-7) while another sets >200 mA/cm2 and about 30,000 h.[3](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf)\n\n## References\n\n1. [Electrochemical CO2 Reduction Reaction: Comprehensive Strategic Approaches to Catalyst Design for Selective Liquid Products Formation](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202402477)\n2. [Electrochemical conversion of CO2 to useful chemicals: current status, remaining challenges, and future opportunities](https://www.sciencedirect.com/science/article/abs/pii/S2211339813000294)\n3. [CO2 electrochemical reduction: A state-of-the-art review with economic and environmental analyses](https://iris.unica.it/retrieve/785a7c55-d2d2-44ac-91d5-6e7addaa8633/leonzio%20anna.pdf)\n4. [Mechanistic insights and strategies for advancing electrochemical CO2 reduction to single products (Cell Reports Physical Science, 2026)](https://doi.org/10.1016/j.xcrp.2026.103415)\n5. [Performing electrocatalytic CO2 reduction reactions at a high pressure](https://link.springer.com/article/10.1007/s43979-024-00106-7)\n6. [Accelerating electrochemical CO2 reduction to multi-carbon products via asymmetric intermediate binding at confined nanointerfaces](https://www.nature.com/articles/s41467-023-36926-x)\n7. [Reduction to Chemicals and Fuels: Thermocatalysis versus Electrocatalysis](https://oar.a-star.edu.sg/storage/p/prrv01jqde/chem-eng-j-472-2023-145033-oar.pdf)\n8. [Advances and challenges in the electrochemical reduction of carbon dioxide](https://pmc.ncbi.nlm.nih.gov/articles/PMC11134526/)\n9. [Catalysts for selective CO2/CO electroreduction to C3+ compounds](https://pubs.rsc.org/en/content/articlepdf/2025/ey/d5ey00047e)\n10. [Continuous Carbon Dioxide Electroreduction to Concentrated Multi-carbon Products Using a Membrane Electrode Assembly (Joule, 2019)](https://doi.org/10.1016/j.joule.2019.07.021)\n11. [Yoshio Hori, Akira Murata, Ryutaro Takahashi (1989). Formation of hydrocarbons in the electrochemical reduction of carbon dioxide at a copper electrode in aqueous solution. Journal of the Chemical Society Faraday Transactions 1 Physical Chemistry in Condensed Phases.](https://doi.org/10.1039/f19898502309)\n12. [Gaseous CO2 electrolysis: latest advances in electrode and electrolyzer technologies toward abating CO2 emissions](https://pubs.rsc.org/be/content/articlehtml/2026/sc/d5sc08419a?page=search)\n13. [Electroreduction of Carbon Dioxide into Formate: A Comprehensive Review](https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/celc.202100438)\n14. [Prototype Validation of a Large-Scale CO2-to-Formate Zero-Gap Electrolyzer](https://pmc.ncbi.nlm.nih.gov/articles/PMC12456378/)\n15. [Electrocatalytic reduction of CO2 to ethylene and ethanol through hydrogen-assisted C–C coupling over fluorine-modified copper](https://www.nature.com/articles/s41929-020-0450-0)\n16. [Selective and Stable Ethanol Synthesis via Electrochemical CO2 Reduction in a Solid Electrolyte Reactor](https://www.osti.gov/pages/servlets/purl/2502105)\n17. [Review on Electrocatalytic CO2 Reduction: From Molecular Mechanisms to Scalable Systems](https://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.5c03120)\n18. [Electroreduction of CO2/CO to C2 Products: Process Modeling, Downstream Separation, System Integration, and Economic Analysis](https://omoultosethtudelft.github.io/web/assets/publications/64.Ramdin_IECR_2021_60_17862.pdf)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Chemical principles and methods › Chemical synthesis › Sonochemical and energy-assisted synthesis*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction", "markdown_url": "https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Electrocatalytic carbon dioxide reduction\", Edgepedia (EdgeChat), https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction. Edgepedia Community License 1.0.", "credit_md": "\"[Electrocatalytic carbon dioxide reduction](https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction](https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Electrocatalytic carbon dioxide reduction\", Edgepedia (EdgeChat), https://www.edgepedia.org/electrocatalytic-carbon-dioxide-reduction. Edgepedia Community License 1.0.", "speakable": "Electrocatalytic carbon dioxide reduction is an electrochemistry method that uses electric current and a catalyst to convert CO2 into chemicals such as ethylene and ethanol." }