03 Fakultät Chemie

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/4

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Institute: search.filters.UBSInstitut.Institut für Technische ChemieAuthor: search.filters.author.Sarkar, Biprajit

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    Ruthenium complexes of polyfluorocarbon substituted terpyridine and mesoionic carbene ligands : an interplay in CO2 reduction
    (2023) Stein, Felix; Nößler, Maite; Singha Hazari, Arijit; Böser, Lisa; Walter, Robert; Liu, Hang; Klemm, Elias; Sarkar, Biprajit
    In recent years terpyridines (tpy) and mesoionic carbenes (MIC) have been widely used in metal complexes. With the right combination with a metal center, both of these ligands are individually known to generate excellent catalysts for CO2 reduction. In this study, we combine the potentials of PFC (PFC=polyfluorocarbon) substituted tpy and MIC ligands within the same platform to obtain a new class of complexes, which we investigated with respect to their structural, electrochemical and UV/Vis/NIR spectroelectrochemical properties. We further show that the resulting metal complexes are potent electrocatalysts for CO2 reduction in which CO is exclusively formed with a faradaic efficiency of 92 %. A preliminary mechanistic study, including the isolation and characterization of a key intermediate is also reported.
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    Remarkable enhancement of catalytic activity of Cu‐complexes in the electrochemical hydrogen evolution reaction by using triply fused porphyrin
    (2022) Chandra, Shubhadeep; Singha Hazari, Arijit; Song, Qian; Hunger, David; Neuman, Nicolás. I.; Slageren, Joris van; Klemm, Elias; Sarkar, Biprajit
    A bimetallic triply fused copper(II) porphyrin complex (1) was prepared, comprising two monomeric porphyrin units linked through β-β, meso-meso, β′-β′ triple covalent linkages and exhibiting remarkable catalytic activity for the electrochemical hydrogen evolution reaction in comparison to the analogous monomeric copper(II) porphyrin complex (2). Electrochemical investigations in the presence of a proton source (trifluoroacetic acid) confirmed that the catalytic activity of the fused metalloporphyrin occurred at a significantly lower overpotential (≈320 mV) compared to the non‐fused monomer. Controlled potential electrolysis combined with kinetic analysis of catalysts 1 and 2 confirmed production of hydrogen, with 96 and 71 % faradaic efficiencies and turnover numbers of 102 and 18, respectively, with an observed rate constant of around 107 s-1 for the dicopper complex. The results thus firmly establish triply fused porphyrin ligands as outstanding candidates for generating highly stable and efficient molecular electrocatalysts in combination with earth‐abundant 3d transition metals.