STUDY ON ELECTROCATALYTIC REDUCTION OF CO2

What is it about?

Several research to explore the possible conversion of CO2 using rhenium(I) tricarbonyl complexes have been reported the last years. In the present work, we investigated a potential use of fac-Re(CO)3(4,4’-di-methyl-2,2’-bipyridyl)L+ complex (C2), where L is an electron-withdrawing ancillary ligands which present an intramolecular hydrogen bond (IHB), in a preliminary electrocatalytic reduction of CO2. The C2 complex was synthesized and characterized according to reported methods earlier. The cyclic voltammogram profile for the C2 complex were studied in dichloromethane under inert atmosphere, and it shows a typical behavior for an electrocatalytic process, the C2 complex illustrate the electrochemical reaction mechanism corresponds to an electrochemical–chemical–electrochemical pathway (ECE). Also, a Vitreous Carbon plate used as working electrode was employed and modified by cycling the anodic region of C2 in CH2Cl2 which involve the oxidative redox response for the -NH2 and -OH groups. The voltammogram profile involve shows a polymeric deposit on the plate surface in a CO2 saturated solution (pH=7.0). A strong electrocatalytic discharge of current is obtained with a wave foot of -1.3 V showing that C2 have the potential to be used in electrocatalyst CO2 reduction.

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Why is it important?

According to the results presented in this study, we conclude that the potential of the fac-Re(CO)3(N,N)L+ complex as electrocatalytic agent depends on the nature of the ancillary ligands. In our case, the use of a Schiff base (E)-2-((3-amino-pyridin-4-ylimino)-methyl)-4,6-diterbutylphenol (L) on the rhenium(I) core represent an important focus to modulate the mentioned properties in the manuscript. A preliminary study of the electrocatalytic CO2reduction mediated byC2 was electrochemical characterized in dichloromethane. The Epc value for the reversible couple under CO2 atmosphere was observed at -1.30 V vs SCE (80 mV less negative) and the following reduction process involved an intense unsolved current discharge. Also we observe that when the working electrode is modified by cycling anodic region of C2 in CH2Cl2, a strong electrocatalytic discharge of current is obtained with a wave foot in -1.3 V. Nevertheless, more experimentation is desirable to fully understand this phenomenon. This work is framed in the development of modulating the photophysical properties on the rhenium(I) tricarbonyl core with these kinds of ancillary ligands. 60-61 From the chemical point of view, the modified physicochemical and electrochemical properties modulated the ancillary ligand aimed to obtain catalytic applications of the new rhenium (I) complexes in the CO 2 reduction.

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