Electroreduction of Carbon Dioxide to Acetate using Heterogenized Hydrophilic Manganese Porphyrins

Abstract

The electrochemical reduction of carbon dioxide (CO 2 ) to value-added chemicals is a promising strategy to mitigate climate change. Metalloporphyrins have been used as a promising class of stable and tunable catalysts for the electrochemical reduction reaction of CO 2 (CO 2 RR) but have been primarily restricted to single-carbon reduction products. Here, we utilize functionalized earth-abundant manganese tetraphenylporphyrin-based (Mn-TPP) molecular electrocatalysts that have been immobilized via electrografting onto a glassy carbon electrode (GCE) to convert CO 2 with overall 94 % Faradaic efficiencies, with 62 % being converted to acetate. Tuning of Mn-TPP with electron-withdrawing sulfonate groups (Mn-TPPS) introduced mechanistic changes arising from the electrostatic interaction between the sulfonate groups and water molecules, resulting in better surface coverage, which facilitated higher conversion rates than the non-functionalized Mn-TPP. For Mn-TPP only carbon monoxide and formate were detected as CO 2 reduction products. Density-functional theory (DFT) calculations confirm that the additional sulfonate groups could alter the CÀ C coupling pathway from *CO!*COH!*COH-CO to *CO!*CO-CO!*COH-CO, reducing the free energy barrier of CÀ C coupling in the case of Mn-TPPS. This opens a new approach to designing metalloporphyrin catalysts for two carbon products in CO 2 RR.

Insertion of MXene‐Based Materials into Cu–Pd 3D Aerogels for Electroreduction of CO2to Formate

“…[ 4,5 ] In aqueous environments, CO 2 RR can produce a number of reduced materials, including C1 products, such as CO and formate, and C 2 products, like acetate, ethylene, and ethanol. [ 6–10 ] Formate, in particular, represents the most economically‐viable reduction product from CO 2 due to its industrial value and requirement of only 2 electrons. [ 11,12 ]…”

“…[4,5] In aqueous environments, CO 2 RR can produce a number of reduced materials, including C1 products, such as CO and formate, and C 2 products, like acetate, ethylene, and ethanol. [6][7][8][9][10] Formate, in particular, represents the most economically-viable reduction product from CO 2 due to its industrial value and requirement of only 2 electrons. [11,12] To date, the majority of catalysts able to produce formate through CO 2 RR are pure post-transition metal catalysts such as Sn, [9,[13][14][15][16] In, [17,18] and Pb, [19,20] ; however, large overpotentials are required to activate CO 2 on these metals compared to transition metal catalysts for CO production.…”

Metal sulfide-based nanomaterials for electrochemical CO2 reduction

“…The low current density (j < 200 mA cm −2 ) and poor faradaic efficiency (FE<90%) are insufficient to meet the scale-up demands. [58][59][60] As the reduction process produces several products and intermediates, it makes the reaction paths more complex. Finally, the reaction selectivity is found to be considerably lower due to a competitive HER.…”

Metal–Organic Framework Derived Cu−Ag Interface for Selective Carbon Monoxide Electroreduction to Acetate

“…Electrochemically conversion of carbon dioxide (CO 2 ) into high‐value chemicals is an important topic for energy safety [1–5] . However, this process suffers from a CO 2 energy penalty and low C 2+ selectivity.…”