Tsukuba, Japan—Similar to the process of photosynthesis in plants, the conversion and storage of solar energy into chemical energy hold significant promise for addressing critical energy and environmental challenges, including the depletion of fossil fuels and threat of global warming. One promising avenue in this pursuit involves harnessing light energy to convert CO 2 into value-added chemicals.
In this study, the researchers harnessed the potent photocatalytic properties of a ruthenium (Ru) dinuclear complex with self-photosensitizing capabilities to achieve a remarkably efficient CO 2 reduction reaction. This process yields a remarkably high selectivity for carbon monoxide (CO). When a dimethylacetamide/H₂O mixture containing the Ru dinuclear complex as a photocatalyst and a sacrificial reducing agent was exposed to light with a central wavelength of 450 nm in 1 atm CO 2 atmosphere for 10 h, all the sacrificial reducing agent was consumed, and the substrate CO 2 was converted into CO with a selectivity exceeding 99%. The maximum quantum yield at 450 nm was determined to be 19.7%. Furthermore, even when the initial CO 2 concentration in the gas phase was reduced to 1.5%, the photocatalytic CO 2 reduction by the Ru complex proceeded with remarkable efficiency, indicating that nearly all the introduced CO 2 could be converted into CO.
In this newly developed Ru dinuclear complex, the two Ru complex moieties engage in photosensitization, enhancing the stability of the complex catalyst under reaction conditions. This enhanced stability is attributed to the extraordinarily strong chelating effect of the ligand employed. The researchers have future plans for further enhancing the catalytic activity to create a reaction system capable of efficiently driving the CO 2 reduction process, even at a lower CO 2 concentration equivalent to that of the Earth's atmosphere, which is approximately 420 ppm.
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This work was supported by Grants-in-Aid (nos. 21K18973 and 21H01947) from the Japan Society of Promotion of Science (JSPS, MEXT) and a Grant-in-Aid for Transformative Research Areas (A) Green Catalysis Science for Renovating Transformation of Carbon-Based Resources (Green Catalysis Science) (JSPS KAKENHI grant no. JP23H04902).
Title of original paper:
Self-Photosensitizing Dinuclear Ruthenium Catalyst for CO 2 Reduction to CO
Journal:
Journal of the American Chemical Society
DOI:
10.1021/jacs.3c07685
Professor KOJIMA, Takahiko
Department of Chemistry, Institute of Pure and Applied Sciences, University of Tsukuba
Institute of Pure and Applied Sciences
Journal of the American Chemical Society
Self-Photosensitizing Dinuclear Ruthenium Catalyst for CO2 Reduction to CO
13-Oct-2023