2019 Fiscal Year Research-status Report
Electrocatalytic Reductive Functionalization of Carbon Dioxide
| Project/Area Number |
19K15671
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
Li Yamei 東京工業大学, 地球生命研究所, 研究員 (10745128)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Keywords | Carbon dioxide reduction / Bio-inspired catalysis / Electrocatalysis / Energy conversion / Thiamin pyrophosphate |
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| Outline of Annual Research Achievements |
For reductive functionalization of CO2, currently, several amine compounds have been used as functionalization agents. However, after trying several metal sulfides as catalysts, no C-N bonded products were detected even with extensive parameter optimization. Therefore, the activation of CO2 is still the bottleneck. This led me to explore a bio-mimetic strategy to activate CO2 by using organic cofactor-like molecules.
Thiamin pyrophosphate (TPP) is an essential cofactor in biological reductive tricarboxylic acid cycle, where CO2 fixations lead to the conversion of acetyl-CoA and succinyl-CoA to pyruvate and alfa-ketoglutarate, respectively. Here I utilized a heterocyclic compounds as an analog of TPP. The TPP-analog was found to reduce CO2 to generate formate, acetate, methanol and ethanol.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Although the original plan to reduce CO2 using amine as functionalization agent does not progress smoothly as expected, this inspired me to explore the bio-inspired CO2 fixation system. The newly explored TPP-analog was found to effectively lower down the onset potential for CO2 fixation as well as affect the product distribution.
Not only simple C1 compounds, alcohols and acetate were also identified as the major products.This system has not been explored before, thus is promising to pave a new way for effective electroreduction of CO2. Moreover, since the introduced TPP analog is working as a homogeneous cocatalyst, it can work as a model system to bridge the understanding on how the cofactor functions to lower down the activiation barrer as well as facilitae the C-C coupling reactions.
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| Strategy for Future Research Activity |
Firstly, the newly developed TPP-analog faciliated CO2 reduction system will be further investigated, in terms of the kinetic dependence on multiple parameters. These parameters include pH, buffer composition, catalyst type and electrode potential. Meanwhile, the product distribution will be analyzed as a function of these parameters.
Secondly, the reaction mechanism of TPP-analog faciliated CO2 reduction will be investigated, using combined eletrochemical and spectroscopic approaches. Electrokinetics can provide insights into the nature of the rate-limiting step. Operando Raman spectroscopy can help understand the nature of substrate-catalyst interaction and how the evolution of surface species occurs with the change in potentials and how such evolution affects the reactivity observed.
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| Causes of Carryover |
In the next fiscal year, the budget will be used for the following items with specific reasons:
1) Purchasing chemicals and CO2 gas. Chemicals will be used for the synthesis of catalyst, preparing electrolyte, preparing buffer solutions for the chemical analysis, etc.
2) Purchasing 13C-labeled bicarbonate. In order to track the source of carbon in the product and ensure that the products are indeed generated from CO2 or bicarbonate, isotope labeled chemicals are to be purchased.
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