Carbon neutral electrochemical conversion of carbon dioxide mediated by [Mⁿ⁺(cyclam)Cl_n] (M = Ni²⁺ and Co³⁺) on mercury free electrodes and ionic liquids as reaction media

Abstract

Carbon dioxide is reduced to carbon monoxide with high faradaic efficiency on mercury free electrodes using M(cyclam) complexes.

Transition metal-based catalysts for the electrochemical CO2reduction: from atoms and molecules to nanostructured materials

“…The catalytic behavior of [Ni(cyclam)] 2+ was also explored in ionic liquids, showing better activity and selectivity for CO production by using the hydrophilic 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF 4 ) solvent/electrolyte system. 232 On the other hand, an unexpected change of selectivity was observed by using DMF with low water content as reaction medium, resulting in the production of CO/HCOO À mixtures depending on the applied potential (FE HCOO À up to 75%). 211 This apparently counterintuitive behavior was ascribed to the formation of an alternative Ni-Z 1 -OCO adduct, which however was predicted to be energetically less favored than the Z 1 -CO 2 one.…”

Electrochemical CO2 and Proton Reduction by a Co(dithiacyclam) Complex

“…Electrochemical studies on the CO 2 reduction by a Co III complex bearing L1 as ligand were hitherto only reported in ionic liquids. [37] Although Co III (L1) is able to serve as catalyst precursor and reduces CO 2 to CO, the comparable Ni II (L1) complex reveals a ten times higher turnover number as well as a significantly better overall performance. [37] Inspired by the sulfur-rich coordination environment of the active centers of CO dehydrogenases and hydrogenases, incorporation of sulfur into the macrocyclic cyclam platform revealed Ni II (L4) (L4 = dithiacyclam, 1,8-dithia-4,11-diazacyclotetradecane) and enabled a facilitated CO 2 reduction at more positive potentials and an enhanced H 2 evolution capa-bility relative to Ni II (L1).…”

“…[37] Although Co III (L1) is able to serve as catalyst precursor and reduces CO 2 to CO, the comparable Ni II (L1) complex reveals a ten times higher turnover number as well as a significantly better overall performance. [37] Inspired by the sulfur-rich coordination environment of the active centers of CO dehydrogenases and hydrogenases, incorporation of sulfur into the macrocyclic cyclam platform revealed Ni II (L4) (L4 = dithiacyclam, 1,8-dithia-4,11-diazacyclotetradecane) and enabled a facilitated CO 2 reduction at more positive potentials and an enhanced H 2 evolution capa-bility relative to Ni II (L1). [38] Based on the insufficient electrochemical investigations of the Co II (cyclam) system and our latest results comparing the electrocatalytic activity of Ni II complexes comprising L1 and L4, we became interested in a directed approach to obtain Co II (L1) and the hitherto unknown Co II complex of L4.…”

“…Instead, a [Co II ( L )(H)] 2+ intermediate is generated and is responsible for the formate production. Electrochemical studies on the CO 2 reduction by a Co III complex bearing L1 as ligand were hitherto only reported in ionic liquids . Although Co III ( L1 ) is able to serve as catalyst precursor and reduces CO 2 to CO, the comparable Ni II ( L1 ) complex reveals a ten times higher turnover number as well as a significantly better overall performance …”

Electrochemical Determination of N,n-Dimethyltryptamine in Water Based on Tetraruthenated Porphyrins and Ionic Liquid Modified Electrodes

“…These kinds of macrocycles are particularly attractive because they display unusual electrocatalytic [21,22] and photoelectrochemical [23,24] properties. In particular, these porphyrins have been used in the electroanalytical detection of S (IV) oxoanions [25][26][27] and the electrocatalytic reduction processes of O2 [28] and CO2 [29,30]. In all cases, a multielectron transfer is essential to the enhancement of the catalytic activity [25][26][27][28]31].…”