Imidazolium Ions with an Alcohol Substituent for Enhanced Electrocatalytic Reduction of CO₂

Abstract

Electrochemical reduction of CO to CO is an attractive process for carbon capture and energy regeneration. Imidazolium ionic liquids (IMILs) are promising electrolyte catalytically active additives for this important reaction. Herein, we report functionalizing the imidazolium ion with a propanol substituent at the N site can significantly enhance the catalytic activity of IMILs, causing a positive shift of the onset potential for the CO reduction by about 90 mV in an acetonitrile electrolyte. Theoretical calculations indicated that the propanol hydroxyl could bridge a local hydrogen-bonding chain as shortcut for proton transfer, leading to a dramatic decrease of the activation barrier for the catalytic reduction of CO in IMIL.

Electroreduction of CO2 and Quantification in New Transition-Metal-Based Deep Eutectic Solvents Using Single-Atom Ag Electrocatalyst

“…The −1.5 V vs Ag/AgCl potential assumed for CO 2 •– free radical formation was maintained during the process, similar to previous reports. For instance, the reports do not use deep eutectic solvents (DESs) but instead DES analogues such as 50 mol % of [Emim][TFO]/10 mM KHCO 3 /H 2 O, 54 0.1 M n -Bu 4 NPF 6 /2.0 mM [C 10 mim][BF 4 ] + 1.0% H 2 O/acetonitrile, 55 and 8 mM [POHmim]BF 4 /acetonitrile. 53 Accordingly, the corresponding potentials recorded for CO 2 electroreduction in these media in chronological order are (−1.8 V vs Ag/AgCl), (−2.3 V vs Fc+/Fc), and (−2.5 V vs Fc+/Fc), respectively.…”

Electroreduction of CO2 in Ionic Liquid-Based Electrolytes

“… 59 Rough Ag 8 mM [POHmim]BF 4 i /acetonitrile −2.5 versus Fc + /Fc c 16.4 CO 92 Zhang et al. 60 Ag nanoflowers (flow cell with electrolyte flow-through rates of 100 mL min −1 ) [Emim]BF 4 /H 2 O (92/8 v/v %) −1.8 V versus Pt 36.6 ( j CO j ) CO 75 Vedharathinam et al. 34 Ag, Au, or Pt 0.1 mol L −1 [P 66614 ]124Triz/acetonitrile/0.7 mol L −1 H 2 O −0.7 V versus Ag/AgNO 3 – HCOO − (on Ag catalysts) Syngas (on Ag, Au, and Pt) 95 (HCOO − on Ag catalysts) Hollingsworth et al.…”

A General and Facile Approach for the Electrochemical Reduction of Carbon Dioxide Inspired by Deep Eutectic Solvents

“…As mentioned above, the application of [Ch]Cl additives in an aqueous electrolyte was demonstrated before . However, employing 1 m [Ch]Cl in water as the electrolyte was rather discouraging, that is, hydrogen was the main product of the reduction with only traces of CO formed (Table ).…”

“…The presence of the hydroxy group in the structure of the IL cation or in close proximity to a catalytic metal center in an appropriate complex further enhances the CO 2 RR. A positive influence was also observed for the hydrolysis of cations in the proximity of the electrode or for the presence of water in the electrolyte .…”

“…The hydroxy‐functionalized IL 1‐(3‐hydroxypropyl)‐3‐methylimidazolium tetrafluoroborate, [PMImOH][BF 4 ], was found to be a promising promoter for CO 2 RR . Inspired by this work, we decided to broaden our IL scope with 1‐(2‐hydroxyethyl)‐3‐methylimidazolium chloride.…”