PDF Publication Title:
Text from PDF Page: 004
Fig. 5. (A) Linear-sweep voltammograms for RuPC/NPC in Ar- or CO2-saturated 0.5 M KHCO3 aqueous solutions. (B) Faradaic efficiencies for ethanol, acetate, methanol, formate, and CO production on RuPC/NPC over a 1-h period. (C) Mole ratios of H2/CO produced on RuPC/NPC. (D) Faradaic efficiencies for C2 products at NPC or RuPC/NPC electrodes over a 1-h period in 0.5 M KHCO3 aqueous solutions. dependent H2/CO ratios can meet the requirements for down- stream chemical and fuel production (36). The NPC electrode also reduced CO2 to ethanol, acetate, methanol, formate, and CO, but the product distribution was different from the RuPC/NPC electrode. Fig. 5D compares C2 product efficiencies between NPC and RuPC/NPC. Ethanol ef- ficiency on RuPC/NPC was enhanced by 1.9 to 2.2 times relative to that on NPC, from −0.87 to −1.07 V (vs. NHE), but there was no obvious difference in acetate efficiency with or without the Ru(II) polypyridyl carbene catalyst. Since CO is the only product of CO2 reduction by the Ru(II) polypyridyl carbene (22, 27, 28), the high ethanol efficiency for RuPC/NPC must arise from the synergistic effect of Ru(II) polypyridyl carbene and NPC at the interface. The potential for CO2 reduction on RuPC/NPC is more pos- itive than for the Ru(II) polypyridyl carbene in solution (−1.20 to −1.50 V vs. NHE) (27, 28) or as heterogenous catalyst (−0.96 to −1.16 V vs. NHE) (22). Dimerization or protonation of adsorbed CO have been reported as the main pathways for C2 production (SI Appendix, Fig. S8) (30, 31, 37). CO2 reduction on Ru(II) polypyridyl carbene occurs through initial 2e− transfer to the ligands, followed by reaction with CO2 to give [RuII(tpy)(Mebim-py)(COO2−)]0, and 1e−/1H+ reduction to give [RuII(tpy−)(Mebim-py)(COOH)]0. In the subsequent steps, it undergoes further reduction to give [RuII(tpy−)(Mebim-py)(CO)]+ as the intermediate (27, 28). The enhanced ethanol efficiency for RuPC/NPC may arise from that CO intermediates adsorbed at the Ru polypyridyl carbene, [RuII(tpy−)(Mebim-py)(CO)]+, are transformed to C2 products at the RuPC/NPC interface by C–C coupling between CO intermediates or intermediates from CO protonation. The porous structure of RuPC/NPC probably can facilitate C–C coupling reaction via nanoconfinement of CO2 or CO2 reduction intermediates (38, 39). The results highlighted here point to the strategy, assembling molecular complexes that are active toward producing C1 intermediates on carbon materials where C–C coupling can occur, being promising for steering CO2 electroreduction toward multicarbon products. Achieving high stability is a significant challenge for heter- ogenous molecular catalysis. For CO2 reduction by the RuPC/ NPC electrode, electrochemical reduction was investigated over a 3-h electrolysis period at −0.97 V (vs. NHE) in 0.5 M KHCO3 aqueous solution. During the electrolysis period, the current density for RuPC/NPC was nearly stable except an initial de- crease (break-in period) (Fig. 6A). The Faradaic efficiency for multicarbon products, ethanol, and acetate was 33.1 to 37.3% for a 3-h experiment (Fig. 6B), and the efficiencies for other CO2-reduction products presented no obvious change, sug- gesting that the RuPC/NPC electrode was stable during 3 h of CO2 reduction. A Leach test with inductively coupled plasma atomic emission spectroscopy analysis confirmed its stability (details are in SI Appendix). The RuPC/NPC hybrid catalyst is more stable than the reported Ru(II) polypyridyl carbene het- erogeneous catalyst, which has a lifetime of ∼15 min under similar conditions (22). Conclusions A method is described here for constructing a heterogenous molecular catalyst that steers electroreduction of CO2 toward C–C-bonded products, notably ethanol. It is based on anchor- ing a Ru(II) polypyridyl carbene complex on NPC. With the synergistic effects of the Ru(II) polypyridyl carbene catalyst for CO intermediate production and NPC for C–C coupling, electrochemical reduction of CO2 to ethanol occurs with a Faradaic efficiency of 27.5% at relatively low overpotentials. Appearance of ethanol is in competition with a syngas mixture of H2/CO at a mole ratio of 2.0 to 2.9. The RuPC/NPC elec- trocatalyst is stable toward CO2 reduction for a period of 3 h and adds a promising lead for the reduction of CO2 to multicarbon products. 4 of 6 | www.pnas.org/cgi/doi/10.1073/pnas.1907740116 Liu et al. Downloaded by guest on May 6, 2021PDF Image | Steering CO2 electroreduction toward ethanol production
PDF Search Title:
Steering CO2 electroreduction toward ethanol productionOriginal File Name Searched:
co2-electroreduction-ethanol.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)