Electrochemical reduction of CO₂ to ethylene glycol on imidazolium ion-terminated self-assembly monolayer-modified Au electrodes in an aqueous solution

Abstract

Imidazolium ion-terminated self-assembled monolayer (SAM)-modified electrodes achieve CO2 conversion while suppressing hydrogen evolution. Immobile imidazolium ion on gold (Au) electrodes reduce CO2 at low overpotential. The distance between electrode and imidazolium ion separated by alkane thiol affects CO2 reduction activity. CO2 reduction current depends on the tunnel current rate. Although the product of CO2 reduction at the bare Au electrode is CO, SAM-modified electrodes produce ethylene glycol in aqueous electrolyte solution without CO evolution. The faradaic efficiency reached a maximum of 87%. CO2 reduction at SAM-modified electrodes is unaffected by reduction activity of Au electrode. This phenomenon shows that the reaction field of CO2 reduction is not the electrode surface but the imidazolium ion monolayer.

Selective and Efficient Reduction of Carbon Dioxide to Carbon Monoxide on Oxide‐Derived Nanostructured Silver Electrocatalysts

“…Over the past few decades,several catalyst materials with the capability of reducing CO 2 electrochemically in CO 2 saturated-aqueous solutions have been identified. [3,[7][8][9][10][11][12][13][14][15][16][17][18] It has been demonstrated that polycrystalline Au is capable of reducing CO 2 to CO with ah igh faradaic efficiency (FE) of about 87 %a tÀ0.74 vs.r eversible hydrogen electrode (RHE). [5] While Au is currently the most efficient electrocatalytic surface for CO 2 reduction to CO,the low abundance and high cost of Au may prevent its large-scale applications.…”

Alkalinity Initiated Decomposition of Mediating Imidazolium Ions in High Current Density CO2 Electrolysis

“…The use of ionic liquid (IL) based electrolytes for the reduction of CO 2 provides numerous advantages. Among these advantages are the impact on the overpotential, the competing hydrogen evolution reaction (HER), the product selectivity, and the product scope . Especially, ILs featuring imidazolium cations have emerged as versatile co‐catalysts.…”

“…Amongt hese advantagesa re the impact on the overpotential, [8][9][10] the competing hydrogen evolutionr eaction (HER), [11][12] the product selectivity, [13][14] and the product scope. [15][16][17][18] Especially,I Ls featuring imidazolium cations have emergeda sv ersatile co-catalysts. The activation of CO 2 in these systems is believed to proceed throughn ucleophilic-heterocyclic-carbenes (NHC) generated in situ.…”

Electrochemical Reduction of CO2 over Heterogeneous Catalysts in Aqueous Solution: Recent Progress and Perspectives

“…This hypothesis has been verified by Chang and co‐workers, using N‐heterocyclic carbene with further modification on molecular structure (Figure b). Other relevant studies have been reported as well, such as Wallace et al, Wang and co‐workers, and Tamura et al…”

“…This hypothesis has been verified by Chang and co-workers, using N-heterocyclic carbene with further modification on molecular structure (Figure 9b). Other relevant studies have been reported as well, such as Wallace et al, [34] Wang and co-workers, [91] and Tamura et al [92] Besides, Sargent and co-workers [18] theoretically calculated that K + ions adsorbed on local sites of Au surfaces could significantly lower the energy barriers of activation for CO 2 to CO. Moreover, they also identify the tip part of needle-like Au with high radius of curvature could generate high electric field, leading to strengthen adsorption of K + ions at tip parts of Au needles (Figure 9c-f).…”