Abstract
Electrochemical conversion of CO2 to alcohols is one of the most challenging methods of conversion and storage of electrical energy in the form of high-energy fuels. The challenge lies in the catalyst design to enable its real-life implementation. Herein, we demonstrate the synthesis and characterization of a cobalt(III) triphenylphosphine corrole complex, which contains three polyethylene glycol residues attached at the meso-phenyl groups. Electron-donation and therefore reduction of the cobalt from cobalt(III) to cobalt(I) is accompanied by removal of the axial ligand, thus resulting in a square-planar cobalt(I) complex. The cobalt(I) as an electron-rich supernucleophilic d8-configurated metal centre, where two electrons occupy and fill up the antibonding dz2 orbital. This orbital possesses high affinity towards electrophiles, allowing for such electronically configurated metals reactions with carbon dioxide. Herein, we report the potential dependent heterogeneous electroreduction of CO2 to ethanol or methanol of an immobilized cobalt A3-corrole catalyst system. In moderately acidic aqueous medium (pH = 6.0), the cobalt corrole modified carbon paper electrode exhibits a Faradaic Efficiency (FE%) of 48 % towards ethanol production.
Highlights
Electrochemical conversion of CO2 to alcohols is one of the most challenging methods of conversion and storage of electrical energy in the form of high-energy fuels
The modified carbon paper electrodes are stable in aqueous solution due to the insolubility of the Co-corrole moiety in water resulting in the formation of a sustainable heterogenized catalyst with extended lifetime for electrocatalysis
To increase the CO2 reduction efficiency and to avoid hydrogen evolution at low-pH values, all experiments were performed under weak acidic conditions
Summary
Electrochemical conversion of CO2 to alcohols is one of the most challenging methods of conversion and storage of electrical energy in the form of high-energy fuels. CO2 reducing catalysts end up accruing lot of energy to be operational at a higher potential In this regard the use of a molecular catalyst with earth abundant elements, (Fe, Mn, Co, Cu, and Ni), especially with a cobalt metal center[11,12] is a viable alternative as it offers a high degree of tunability with product selectivity at a low overpotential. FE (93 %) and selectivity for conversion to ethanol, but work at higher overpotentials[10] Such heteroatom-doped materials[32] often require a sophisticated synthetic procedure like chemical vapor deposition, making it hard for large scale implementation[33]. We compare and contrast state of the art catalysts for CO2 electro-reduction to ethanol, all of which work at higher overpotentials with shorter activity time and have lower
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