The electrochemical reduction of carbon dioxide (CO2) to value-added materials has received considerable attention. Both bulk transition metal catalysts, and molecular catalysts affixed to conductive non-catalytic solid supports, represents a promising approach towards electroreduction of CO2. Here, we report a combined silver (Ag) and pyridine catalyst through a green and irreversible electrografting process, which demonstrates enhanced CO2 conversion versus the individual counterparts. We find by tailoring the pyridine carbon chain length, a 200 mV shift in the onset potential is obtainable compared to the bare silver electrode. A 10-fold activity enhancement at -0.7 V vs RHE is then observed with demonstratable higher partial current densities for CO indicating a co-catalytic effect is attainable through the integration of the two different catalytic structures. We extended performance to a flow cell operating at 150 mA/cm 2 , demonstrating the approach's potential for substantial adaption with various transition metals as supports, and electrografted molecular co-catalysts.

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.

The abstract should be a single paragraph that summarises the content of the article 2,5-furandicarboxylic acid (FDCA) is an eco-friendly substitute of fossil fuel-derived polymers that can be produced from...

Molecular catalysts play a significant role in chemical transformations, utilizing changes in redox states to facilitate reactions. In the broadening field of carbon dioxide (CO2) electrolysis to value-added products, catalyst choice strongly impacts product formation. To date molecular electrocatalysts have efficiently produced single-carbon products from CO21–3 but have struggled to achieve the carbon-carbon coupling step needed to reach highly valued multi-carbon products. Conversely, copper acts as the only reliable bulk metal that enables carbon-carbon coupling, but leads to broad C2+ product spectrums.3–5 Here we designed a molecular electrocatalyst system that subverts the traditional redox-mediated reaction mechanisms of organometallic compounds, facilitating electrochemical CO2-to-ethanol yields of 96% at optimal conditions with trace methanol and C3 products. By coupling iron tetraphenylporphyrin (Fe-TPP) with a nickel electrode, we fixed the iron oxidation state during electrocatalytic CO2 reduction to enable further reductions and coupling of *CO intermediates. This represents a marked behavioural shift compared to the same metalloporphyrin deposited onto carbon-based electrodes. Extending the approach to a 3D porous nickel support with adsorbed Fe-TPP, we attain ethanol faradaic efficiencies of 68% +/- 3.2% at -0.3 V vs a reversible hydrogen electrode (pH = 7.7) with partial ethanol current densities of -21 mA cm-2. Separately we demonstrate maintained ethanol production over 60 hours of operation. Further consideration of the wide parameter space of molecular catalyst and metal electrodes shows promise for additional novel chemistries and achievable metrics.

The electrochemical reduction of carbon dioxide (CO2) to value-added materials has received considerable attention. Both bulk transition metal catalysts, and molecular catalysts affixed to conductive non-catalytic solid supports, represents a promising approach towards electroreduction of CO2. Here, we report a combined silver (Ag) and pyridine catalyst through a green and irreversible electrografting process, which demonstrates enhanced CO2 conversion versus the individual counterparts. We find by tailoring the pyridine carbon chain length, a 200 mV shift in the onset potential is obtainable compared to the bare silver electrode. A 10-fold activity enhancement at -0.7 V vs RHE is then observed with demonstratable higher partial current densities for CO indicating a co-catalytic effect is attainable through the integration of the two different catalytic structures. We extended performance to a flow cell operating at 150 mA/cm2, demonstrating the approach’s potential for substantial adaption with various transition metals as supports, and electrografted molecular co-catalysts.