Noncovalent immobilization of a nickel cyclam catalyst on carbon electrodes for CO2 reduction using aqueous electrolyte

Zero-Gap Bipolar Membrane Electrolyzer for Carbon Dioxide Reduction Using Acid-Tolerant Molecular Electrocatalysts

“…The molecular catalysts studied here are [Ni­(Cyc)] 2+ (Cyc = cyclam = 1,4,8,11-tetraazacyclotetradecane) and its derivative with a pendant carboxylic acid group [Ni­(CycCOOH)] 2+ (CycCOOH = 1,4,8,11-tetraazacyclotetradecane-6-carboxylic acid) which are spray coated onto carbon paper with microporous layers to form the GDE structure (at a loading of 1 mg cm –2 with Nafion solution as binder and ion-transporter, for details see the Supporting Information). [Ni­(Cyc)] 2+ and its derivatives have been studied extensively − in homogeneous systems and shown to have a high CO selectivity in aqueous systems at pH 2–5, with [Ni­(CycCOOH)] 2+ being particularly active at lower pH’s. , The selectivity at a low pH is proposed to be due to a high CO 2 binding constant and a low p K a of the reduced Ni I center. , There are only two prior reports of Ni cyclam-based catalysts immobilized onto a GDE, , and one with the catalyst in a flow cell none of which used an acidic or zero-gap configuration.…”

“…23,25 The selectivity at a low pH is proposed to be due to a high CO 2 binding constant and a low pK a of the reduced Ni I center. 18,19 There are only two prior reports of Ni cyclambased catalysts immobilized onto a GDE, 26,27 and one with the catalyst in a flow cell 25 none of which used an acidic or zerogap configuration. show the scanning electron microscopy (SEM) images and corresponding Ni K α and F K α energy dispersive X-ray spectroscopy (EDX) elemental mapping of [Ni(Cyc)] 2+ on a GDE.…”

CO2 Electroreduction in Water with a Heterogenized C-Substituted Nickel Cyclam Catalyst

“…A gas diffusion electrode with an analogue of complex A developed by Greenwell and collaborators gave also much less selective CO production (FY = 50%) in water. 14 Previous reports discussing the CO/H 2 selectivity in the case of Ni-cyclam and derivatives have rarely considered this possibility of the involvement of the electrode carbon support and not Ni-cyclam for HER. The fact that the carbon electrode is a good HER catalyst allowing HER to compete with CO 2 RR catalyzed by Ni-cyclam in solution has been, for example, discussed by Machan and collaborators.…”

Immobilization strategies for porphyrin-based molecular catalysts for the electroreduction of CO2

“…127 Secondly, covalent immobilization is a more robust alternative to non-covalent approaches which can show signs of catalyst displacement aer several hours of operation. 108,115,128 Here, the ligand groups of the porphyrin must be functionalized in a way that both allows for covalent binding to a surface, without destabilizing the molecule, while also remaining active for CO 2 RR. 112,129 Such an approach provides the opportunity for long-term stability and predictable This journal is © The Royal Society of Chemistry 2022 catalyst orientations, but leads to a high degree of constraints, generally adding complexity to the synthetic approach required.…”