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Ferrous Ions as Catalysts for Photochemical Reduction of CO2 in Homogeneous Solutions



J Grodkowski, Pedatsur Neta


Ferrous ions are found to act as efficient catalysts for the photochemical reduction of CO2 to CO in homogeneous solutions. Photochemical reduction is carried out in acetonitrile (ACN) solutions containing triethylamine (TEA) or triethanolamine (TEOA) as reductive quenchers and p-terphenyl (TP) as a photosensitizer. TP is very effectively photoreduced to form the radical anion, TP.-, which reduces Fe(II) ions. The rate constant for this reaction was determined by pulse radiolysis in ACN/TEOA solutions and found to be 1.2 x 108 L mol-1 s-1. The Fe(I) ions produced are expected to react with CO2 to form an adduct which is equivalent to that formed upon reaction of .CO2- with Fe(II) complexes. Subsequent reduction of the Fe-CO2^ adduct by TP.- or by Fe(I) leads to formation of CO. Fe(I) can also react with protons, present in the medium or produced by the photolysis, to form H2. Production of CO and H2 have different time profiles. After extensive irradiations, photochemical production of CO stops while production of H2 continues. The limit on CO production is due to competition between CO and CO2 for the Fe(I) binding sites. Binding of CO is shown to lead to production of H2.
Journal of Physical Chemistry A
No. 19


carbon dioxide, ferrous ions, iron compounds, photolysis, photoreduction


Grodkowski, J. and Neta, P. (2000), Ferrous Ions as Catalysts for Photochemical Reduction of CO<sub>2</sub> in Homogeneous Solutions, Journal of Physical Chemistry A (Accessed June 12, 2024)


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Created April 30, 2000, Updated October 12, 2021