Direct molten-salt electro-reduction of CO2 in porous electrodes

Shi, Hao; Cai, Muya; Li, Wenting; Chen, Xiang; Du, Keming; Guo, Lei; Wang, Peilin; Li, Peng; Deng, Bowen; Yin, Huayi; Wang, Dihua

doi:10.1016/j.cej.2023.142240

Cited by 11 publications

(9 citation statements)

References 37 publications

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“…The FeNi foam electrode can significantly reduce the diffusion distance between the gaseous CO 2 and the solid electrode (Figure S2a). As demonstrated by previous research, the foam electrode can reduce CO 2 directly to CO instead being indirectly reduced by CO 3 2– . Such a system is not possible without the direct reduction of CO 2 in molten salt, since Na cannot reduce Na 2 CO 3 anyway.…”

Section: Resultsmentioning

confidence: 61%

“…Previous studies have confirmed that a foam FeNi electrode can directly reduce CO 2 to CO in molten salts via short gas-electrode diffusion distance. 27 SEM Photos of a FeNi foamed positive electrode for CO 2 reduction are shown in Figure S8. Here, CO 2 is reduced by Na to produce CO and provides a certain amount of electricity (Figure 4a).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Molten salt CO 2 electroreduction provides another option for producing O 2 and CO or carbon materials on Mars without using water. − CO 2 can be directly reduced to CO in molten salt without the use of expensive catalysts or complex electrode designs, and, at the same time, released O 2 through an inert anode. − Fortunately, the application potential of molten salt electrolytes as a form of energy storage has been demonstrated. − Liquid metal batteries have been constructed by storing active metals such as lithium, sodium, and magnesium . This is a simple and efficient way of storing energy in molten salt electrolytes.…”

Section: Introductionmentioning

confidence: 99%

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Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

Shi

Fang

Cai

et al. 2023

ACS Sustainable Chem. Eng.

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Oxygen and fuels are requisites for outer space exploration. Herein, we use a liquid Na–Sn cathode and a Ni-based inert anode to convert CO2 into Na–Sn and oxygen in molten Na2CO3–NaCl by electrolysis, aiming to produce oxygen and store solar energy in liquid Na–Sn when the sun shines. In the same Na2CO3–NaCl electrolyte, the liquid Na–Sn serves as a negative electrode coupled with a porous FeNi positive electrode that allows the reduction of CO2 to CO in a primary cell, converting chemical energy stored in Na–Sn into electricity and CO that is a valuable fuel when the sun does not shine. This system has an overall energy efficiency of 51.0% at 100 mA cm–2. Therefore, the molten carbonate electrolysis device equipped with a liquid metal electrode could be applied for producing O2 and storing solar energy in energetic chemicals (e.g., Na–Sn, CO), which could be applied for outer space exploration such as Mars.

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Section: Resultsmentioning

confidence: 61%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

Shi

Fang

Cai

et al. 2023

ACS Sustainable Chem. Eng.

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“…The unique physicochemical properties of the melts make it possible to obtain solid carbon directly from CO 2 gas − according to the following reaction. normalC normalO 2 + 4 e − → normalC + 2 normalO 2 − In the case of melts containing oxide ions, CO 2 can be dissolved in the form of carbonate ions normalC normalO 2 + O 2 − → C O 3 2 − The carbonate ions are reduced to the solid carbon on a cathode as follows. C O 3 2 − + 4 e − → normalC + 3 normalO 2 − Many studies on the carbon electrodeposition from carbonate ions in molten alkali carbonate mixtures − and molten halides containing metallic carbonates − have been reported.…”

Section: Introductionmentioning

confidence: 99%

New Route of Acetylene Synthesis via Electrochemical Formation of Metal Carbides from CO₂ in Chloride Melts

Suzuki,

Tanaka,

Watanabe

et al. 2024

ACS Sustainable Chem. Eng.

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Electrochemical conversion of CO 2 in high-temperature molten salts provides a unique process for synthesizing materials that cannot be obtained in low-temperature aqueous systems. In this study, we propose a novel route to produce acetylene utilizing the electrochemical reduction of CO 2 in chloride melts. Acetylene is generated by the reaction between water and metal carbides, which are formed by the reduction of CO 2 and cations in the melts. We demonstrated the proposed process by electrochemical measurements and quantitative gas analysis. To investigate the electrolytic system suitable for forming Li 2 C 2 and CaC 2 as the metal carbides at high current efficiency, two types of melts: LiCl−KCl−CaCl 2 −CaO melt at 723 K and NaCl−KCl−CaCl 2 −CaO melt at 823 K, and two types of electrodes: metallic electrodes (Fe, SUS304, SUS316, Mo, Ta and Ti) and carbon electrodes (graphite, glassy carbon, and highly oriented pyrolytic graphite) were used. It was found that acetylene was obtained with a current efficiency of 68% by galvanostatic electrolysis at −200 mA cm −2 on a Fe electrode in the NaCl−KCl−CaCl 2 −CaO melt mixed with 7.0 mol % CaC 2 under CO 2 atmosphere. The CaC 2 played a key role in preventing the dissolution of electrodeposited metal carbides into the melts.

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“…Notably, for MWCNTs, researchers demonstrated that the Ostwald ripening effects of the catalyst directly modulate MWCNT diameters in a manner analogous to conventional gas-phase catalytic MWCNT growth. ,, However, traditional gas-phase MWCNT synthesis routes commonly utilize a reducing environment involving H 2 , H radicals, or even N 2 H 4 to transform the Fe x O y catalyst into an active zerovalent metal to efficiently support MWCNT growth. , This opens a key question about the electrocatalytic reduction of metal oxide catalysts since no chemical-reducing species are present during electrolysis. Therefore, the understanding and control of catalyst reduction, which has been deemed as critical toward the resulting diameter of the MWCNT in gas-phase MWCNT synthesis methods, remains unexplored for electrocatalytic MWCNT synthesis. , …”

Section: Introductionmentioning

confidence: 99%

Pulsed Current for Diameter-Controlled Carbon Nanotubes and Hybrid Carbon Nanostructures in Electrolysis of Captured Carbon Dioxide

Alaei,

Jiao,

Ghazvini

et al. 2023

ACS Appl. Nano Mater.

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Here, we demonstrate how temporally controlled pulses of current can control the physical properties of multiwalled carbon nanotubes (MWCNTs) synthesized from the electrolysis of air-captured carbon dioxide. Our findings demonstrate that a transient 1 min 7.5-fold rate increase of current or carbonate reduction during nucleation of MWCNTs leads to 2.5 times smaller average MWCNT diameters, a higher degree of graphitization in the walls, and an overall 10% lower energy consumption over the full growth duration. Conversely, when identical transient current pulses are applied after MWCNT nucleation in the middle of CNT growth, our findings indicate the deposition of noncatalytic onionlike carbons on the surface of the MWCNTs to form hybrid nanostructured materials, but no changes are observed to MWCNT diameters, energy consumption, or wall graphitization of the MWCNTs. A detailed study of this system by three-electrode cyclic voltammetry, imaging, X-ray diffraction (XRD), and Raman spectroscopy supports the mechanistic role of current pulses in nucleation to facilitate rapid catalyst reduction and minimize coarsening to sustain catalysts with high activity. This work demonstrates how temporally controlled electrochemical current density, and hence carbon flux, in molten carbonate electrolysis is a powerful tool to engineer the production of carbon nanostructures with tailored physical properties and a total energy consumption footprint.

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Direct molten-salt electro-reduction of CO2 in porous electrodes

Cited by 11 publications

References 37 publications

Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

New Route of Acetylene Synthesis via Electrochemical Formation of Metal Carbides from CO₂ in Chloride Melts

Pulsed Current for Diameter-Controlled Carbon Nanotubes and Hybrid Carbon Nanostructures in Electrolysis of Captured Carbon Dioxide

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Direct molten-salt electro-reduction of CO2 in porous electrodes

Cited by 11 publications

References 37 publications

Liquid Metal–CO2 Battery Bridged Intermittent Energy Conversion and O2 Production in the Martian Atmosphere

Liquid Metal–CO2 Battery Bridged Intermittent Energy Conversion and O2 Production in the Martian Atmosphere

New Route of Acetylene Synthesis via Electrochemical Formation of Metal Carbides from CO2 in Chloride Melts

Pulsed Current for Diameter-Controlled Carbon Nanotubes and Hybrid Carbon Nanostructures in Electrolysis of Captured Carbon Dioxide

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Product

Resources

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Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

Liquid Metal–CO₂ Battery Bridged Intermittent Energy Conversion and O₂ Production in the Martian Atmosphere

New Route of Acetylene Synthesis via Electrochemical Formation of Metal Carbides from CO₂ in Chloride Melts