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Diamonds from the Sky -‐ C2CNT, the Inexpensive Transforma[On of CO2 To Diamonds from the Sky - C2CNT, the inexpensive transformaon of CO2 to carbon nanotubes Stuart Licht, [email protected] presentaon to: the Naonal Academy Washington, DC, March 2018 Not for reproducon. All rights retained by George Washington University. Stuart Licht – 30 years solar chemistry & climate change mitigation expertise Academic credenals Deans’s Research Prof. George Washington Univ. Former NSF Program Director (Chemistry Division) Former Professor Technion Professor of Chemistry Former Chair – UMass Dept. of Chemistry Former Carlson Chair Assoc. Prof. of Chemsitry Postdoc: MIT (with Prof. Mark Wrighton) Ph.D. in chemistry: Weizmann Instute of Science B.Sc. & M.Sc. in chem&phys: Wesleyan University 2 Stuart Licht – 30 years solar chemistry & climate change mitigation expertise ~400 peer reviewed papers & patents 2014 3 Addressing climate change: What if we could convert CO2 to a product worth over 1,000 times more than coal? Money talks loudly. This would provide economic incenve to remove CO2. We can. We do it now. Today, we present an alternave transformaon of carbon dioxide into a compact, stable, valuable product. This process provides an economic incenve to remove the greenhouse gas carbon dioxide. 1 Introduc;on of a soluon to remove atmospheric carbon dioxide & migate climate change A novel, high-yield, low energy process is shown to remove the greenhouse gas carbon dioxide. We have found a chemistry to produce high-yield, high purity, carbon nanotubes and carbon nanofibers products directly from either atmospheric or smokestack CO2. Such carbons are used to make strong carbon composites, such as used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other lightweight, high strength, flexible, products. Carbon nanotubes are easily synthesized here, exhibit high strength to weight raos, high thermal and electrical conducvity and are useful for tomorrow's nanoelectonics and baeries. This direct molten electrolysis transformaon of carbon dioxide to carbon nanotubes is a low cost process, and the high value, demand, compactness & stability of the product is an incen've to remove CO2! How does the carbon dioxide to CNT (cabon nanotube) C2CNT process work? 1 Electrodes are immersed in molten carbonate Li2CO3 Electrical current splits Li2CO3 4e- 4e- O2 C + Li2O Li2CO3 …into carbon & Li2O at the cathode 4e- 4e- O2 C + Li2O Li2CO3 and releasing oxygen gas at the anode 4e- 4e- O2 C + Li2O Li2CO3 CO2(air) connuously replenishes the Li2CO3 + Li2O Li2CO3 carbon dioxide is connuously removed! e-’s CO2(air) è C+O2 e-’ s solid carbon grows on the cathode as CO2 is consumed. carbon dioxide is connuously removed! CO2(air) è C+O2 solid carbon grows on the cathode as CO2 is consumed. The carbon product at the cathode can be pure carbon nanotubes!!! STEP Carbon: Product With control of the electrolysis, the product approaches 100% yield of carbon nanotubes (rather than just graphite) synthesized directly from CO2:* CO2(from air) à molten electrolysis: carbon nanotubes + O2(gas) Scanning Electron Microscopy (SEM) of the carbon nanofiber product: Carbon nanotubes, used in high strength composites are worth >> $100,000/ton, as opposed to coal, worth ~ $40/ton, and graphite worth ~$1,000/ton. an example of applicaons..... How do we know that they are carbon nanotubes ? SEM: (middle) Head-on cross secon view of our electrosynthesized mulwalled carbon nanotubes; (le) tangled CNTs (Li2O in synthesis electrolyte); (right) and straight electrosynthesized CNT (no Li2O). Disorded & Graphic Raman peak & size distribuon of (le) tangled and (right) straight STEP MWCNTs. Licht, Douglas, Ren, Carter, Lefler, Pint: "Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion ," ACS Central Science, 2, 162 (2016). How do we know they are built from CO2? – isotope labels We've synthesized pure 13C mulwalled CNFs, and also from the inexpensive natural abundance CO2 synthesized higher valued CNTs vs CNFs ($200,000 vs $25,000/ton) 13 SEM (top) & TEM (middle & boom): (le) Natural isotope CO2 forms CNTs; (right) pure CO2 forms CNTs Ren, Licht : "Tracking airborne CO2 migaon and low cost transformaon into valuable carbon nanotubes," 13C STEP carbon nanofibers, Scienc Reports – Nature.com published June 9, 6, 27760 (2016). Porolio of CNT and CNF morphologies synthesized at high yield from CO2 in molten carbonate under various electrolysis condions Top row: carbon nanotubes are electrosynthesized in molten lithium carbonate during short (2nd from le) or long duraon electrolyses and right: solid core carbon nanofibers are grown from 13C isotope. Middle row, le: tangled, rather than straight carbon nanotubes are grown from lithium carbonate containing dissolved oxide; a high yield of carbon nanotubes can also be grown by electrolysis from mixed (middle) Ba/LI or (right) Na/Li electrolyses. Boom row, le & middle: high electrical conducvity CNTs are grown from boronated electrolytes and (right) thin walled CNTs are grown from calcinated electrolytes. Ren, Johnson, Singhal, Licht: "Transformaon of the greenhouse gas CO2 by molten electrolysis into a wide controlled selecon of carbon nanotubes ,” J. CO2 Ulizaon, published March 2017. Growth mechanism Transion metals, such as Ni, nucleate electrosynthec molten carbonate CNT growth on the cathode SEM (le) & EDS(right): brights spots are nickel, which act as nucleaon points for CNT growth *Ren, Li, Lau, Gonzalez-Urbina, Licht, ”One-pot synthesis of carbon nanofibers from CO2," Nano Leers, published August 2015, and available free online as an open access arcle Nucleaon variaon provides a path to long CNTs Previously, extended electrolyses had CNT wool growth mechanism: produced fat, short, noodle-like CNTs. The electrical conduc vity of CNTs grown with an increasin CNT Addion of a chromium, in addion g to nickel, transion metal nucleang wool: agent, sustains formaon of very long, thin, macroscopic (over 1 mm long) CNTs, an easier synthesis, and…. CNT wool! Johnson, Ren, Lefler, Licht, Vicini, Liu, Licht: "Carbon Nanotube Wools Made Directly from CO2 By Molten Electrolysis," Materials Today Energy, 5, 230 (2017). CO2-derived CNT anodes in alkali-ion baeries Li-ion anode baery storage capacity in 1 M LiPF6/EC-DC electrolyte Na-ion anode baery storage capacity in 1 M NaPF6/diethylene glycol dimethly ether electrolyte. Licht, Douglas, Ren, Carter, Lefler, Pint: "Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion ," ACS Central Science, 2, 162-168 (2016). Can we fast track CNT producon to lower CO2 (industry applicaon)? 1 step, 1 pot synthesis of doped CNTs Different dopants inserted into the CNT change both the physical and chemical properes of the CNTs. Doped carbons have a range of potenal applicaons, including (B) doped can enhance their conducvity. (S) doped heterogeneous catalysis, sorpon, and energy conversion and storage. (N) doped O2 oxidaon & reducon, fuel cell catalysts, supercapacitors, and sensors. P-doping of carbons including reduced elongaon fracturing, as aerobic oxidaon catalysts, baeries and ultra sensive sensors. Doping is readily accomplished thru electrolyte addives. Shown are the 1st doped electrosynthesized CNTs. Doping dramacally increases the electrical conducvity of CNTs grown with an increasing concentraon of LiBO2 dissolved in the Li2CO3 electrolyte. Ren, Johnson, Singhal, Licht: "Transformaon of the greenhouse gas CO2 by molten electrolysis into a wide controlled selecon of carbon nanotubes ,” J. CO2 Ulizaon, published March 19, 2017. Another near future applicaon of CNT carbon materials is as texles $20,000 carbon nanotube If You Want To Be Immune To Tasers bullet proof, lightweight suit: Just Wear… source: hp://gizmodo.com/if-you-want- 3:16 VIDEO source: to-be-immune-to-tasers-just-wear-carbon-fib-1537135745 hp://garrisonbespoke.com/custom-suits/bulletproof-suit/ “the folks at Hackaday discovered that carbon fiber Applicaons clothing can actually let you shrug off those electric shocks. Carbon they ..lined a sports coat with strips of fiber tape so nanotubes, that the resulng jacket sll had lots of flexibility. exhibit higher The carbon fiber conducts electricity much beer than human skin, and since the strips were placed strength to close enough to let the juice flow between them, weight raos they were able to dissipate the charge without than kevlar, shocking down the dapper-looking target.” high electrical conducvity and are useful for tomorrow's texles. Lightweight, stops 9, 22 & 45 mm bullets Today's natural gas electrical power plants An alternave approach. The carbon nanotube contribute substanally to climate change with natural gas electrical power plants will have no massive emissions of the greenhouse gas CO2. CO2 emissions and produce useful, valuable CNTs. S. Licht et al , "Carbon Nanofiber Electric and Power Plants " Energy Coversion & Management, 2016. The action of a conventional CC (combined cycled) natural gas The CC CNT power plant will have no CO2 emissions. power plant with high CO2 exhaust. The CC plant has two Carbon dioxide instead is electrical turbines and two generators, a high temperature –jet like transformed by electrolysis into valuable carbon nanotubes. tubine, and using its "waste" heat a lower temperature steam turbine. NG CC power plant analyzed wo/w C2CNF (per ton of fuel): without C2CNT, output : 2.7 ton CO2 $909 electricity $0 of CNT; with C2CNT, output : 0.0 ton CO2 $835 electricity $225,000 CNT. Cement Producon today has a massive Carbon Footprint Cement producon today has a massive carbon footprint. Cement producon simultaneously release CO2 both from limestone and from fossil fuels, and hence cement plant smokestacks have much higher CO2 content (5 mes higher than gas fired electric power plants). Interest in Cement/CNT Composites is rapidly growing Cement/CNT composites are much stronger, x more flexible, resist compression and have beer blast. damage and cracking resisance than regular cement. Licht: "Co-Producon of Cement and Carbon Nanotubes with a Carbon Negave Footprint ,” J. CO2 Ulizaon, published March 19, 2017.
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