Amplified CO2 reduction of greenhouse gas emissions with C2CNT carbon nanotube composites

Licht

et al. 2020

Sci Rep

An electrosynthesis is presented to transform CO2 into an unusual nano and micron dimensioned morphology of carbon, termed Carbon Nano-Scaffold (CNS) with wide a range of high surface area graphene potential usages including batteries, supercapacitors, compression devices, electromagnetic wave shielding and sensors. Current CNS value is over $323 per milligram. The morphology consists of a series of asymmetric 20 to 100 nm thick flat multilayer graphene platelets 2 to 20 µm long orthogonally oriented in a 3D neoplasticism-like geometry, and appears distinct from the honeycomb, foam, or balsa wood cell structures previously attributed to carbon scaffolds. The CNS synthesis splits CO2 by electrolysis in molten carbonate and has a carbon negative footprint. It is observed that transition metal nucleated, high yield growth of carbon nanotubes (CNTs) is inhibited in electrolytes containing over 50 wt% of sodium or 30 wt% of potassium carbonate, or at electrolysis temperatures less than 700 °C. Here, it is found that a lower temperature of synthesis, lower concentrations of lithium carbonate, and higher current density promotes CNS growth while suppressing CNT growth. Electrolyte conditions of 50 wt% sodium carbonate relative to lithium carbonate at an electrolysis temperature of 670 °C produced over 80% of the CNS desired product at 85% faradaic efficiency with a Muntz brass cathode and an Inconel anode.

Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

One pot facile transformation of CO2 to an unusual 3-D nano-scaffold morphology of carbon

Licht

et al. 2020

Sci Rep

“…In 2009 and 2010 a novel sunlight driven methodology to split CO 2 into carbon and oxygen by molten carbonate electrolysis was introduced 7,8 . This process does not require sunlight, and it was demonstrated that using a molten carbonate and a variety of electrolytic configurations, the carbon product can be made into pure carbon nanomaterials, such as Carbon Nanotubes (CNTs) [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] . For example, this novel chemistry transforms the greenhouse Carbon dioxide to Carbon NanoTubes (C2CNT), and directly captures and CO 2 from the atmosphere or from concentrated anthropogenic CO 2 sources such as power plant exhaust.…”

Section: Calcium Metaborate Induced Thin Walled Carbon Nanotube Synthmentioning

confidence: 99%

Calcium metaborate induced thin walled carbon nanotube syntheses from CO2 by molten carbonate electrolysis

Licht

et al. 2020

Sci Rep

An electrosynthesis is presented to transform the greenhouse gas CO2 into an unusually thin walled, smaller diameter morphology of Carbon Nanotubes (CNTs). The transformation occurs at high yield and coulombic efficiency of the 4-electron CO2 reduction in a molten carbonate electrolyte. The electrosynthesis is driven by an unexpected synergy between calcium and metaborate. In a pure molten lithium carbonate electrolyte, thicker walled CNTs (100–160 nm diameter) are synthesized during a 4 h CO2 electrolysis at 0.1 A cm−2. At this low current density, CO2 without pre-concentration is directly absorbed by the air (direct air capture) to renew and sustain the carbonate electrolyte. The addition of 2 wt% Li2O to the electrolyte produces thinner, highly uniform (50–80 nm diameter) walled CNTs, consisting of ~ 75 concentric, cylindrical graphene walls. The product is produced at high yield (the cathode product consists of > 98% CNTs). It had previously been demonstrated that the addition of 5–10 wt% lithium metaborate to the lithium carbonate electrolyte boron dopes the CNTs increasing their electrical conductivity tenfold, and that the addition of calcium carbonate to a molten lithium carbonate supports the electrosynthesis of thinner walled CNTs, but at low yield (only ~ 15% of the product are CNTs). Here it is shown that the same electrolysis conditions, but with the addition of 7.7 wt% calcium metaborate to lithium carbonate, produces unusually thin walled CNTs uniform (22–42 nm diameter) CNTs consisting of ~ 25 concentric, cylindrical graphene walls at a high yield of > 90% CNTs.

CO₂ Utilization by Electrolytic Splitting to Carbon Nanotubes in Non‐Lithiated, Cost‐Effective, Molten Carbonate Electrolytes

Licht²,

Advanced Sustainable Systems

et al. 2022

Carbon nanotubes (CNTs), have extraordinarily high tensile strength, electrical and thermal conductivity, and electrical storage capabilities. To date, CNTs have had limited use due to their high synthesis cost. The synthesis costs decrease when CNTs are prepared by transition metal nucleated molten electrolytic CO2 splitting, rather than by conventional chemical vapor deposition or arc deposition techniques. In addition to cost, a second advantage of CNT electrosynthesis is that the process consumes the greenhouse gas CO2 in its transformation to CNTs (and oxygen), providing a path to climate mitigation. However, electrolytic high yield, CNT syntheses has only been demonstrated with expensive lithiated electrolytes, such as pure or mixed Li2CO3. This study demonstrates, after several hundred failures, that carbon nanomaterials, can be synthesized from CO2 in non‐lithiated electrolytes. In the new sodium barium carbonate electrolytes, lower mobility due to the absence of lithium ions is overcome by: i) low current density; or ii) the introduction of oxides, such as BaO, to induce graphene walls to facilitate passage of larger cations during the process of growing CNTs; and/or iii) addition of specific transition metal nucleation agents, such as Fe2O3. The electrolysis uses inexpensive anodes and cathodes to form carbon nanomaterials, including straight and coiled CNTs.