Electrochemical CO₂ Reduction to Ethanol with Copper-Based Catalysts

Abstract

Electrochemical CO 2 reduction presents a sustainable route to storage of intermittent renewable energy. Ethanol is an important target product, which is used as fuel additive and as a chemical feedstock. However, electrochemical ethanol production is challenging as it involves the transfer of multiple electrons and protons alongside C−C bond formation. To date, the most commonly employed and effective catalysts are copper-based materials. This review presents and categorizes the most efficient and selective Cu-based electrocatalysts, which are divided into three main groups: oxide-

Enhanced Ethylene Formation from Carbon Dioxide Reduction through Sequential Catalysis on Au Decorated Cubic Cu2O Electrocatalyst

“…Their results indicated the selectivity of C 2 H 4 to CH 4 in O−Cu combination catalysts was influenced by the electrochemical reduction environment related to the mixed valences. Based on the above characterization results of surface Cu states in our work, it could be explained by high CO * coverage and the preference of C−C coupling over further hydrogenation on the mixed Cu sites [66] . In consequence, the highest FE of C 2 H 4 reached 24.4 % on Au 0.02 Cu 2 O catalyst at a total current density of ∼5.7 mA⋅cm −2 at −1.3 V (Table S3), 4 times that of single Cu 2 O, while CH 4 generation was remarkably suppressed.…”

“…Based on the above characterization results of surface Cu states in our work, it could be explained by high CO* coverage and the preference of CÀ C coupling over further hydrogenation on the mixed Cu sites. [66] In consequence, the highest FE of C 2 H 4 reached 24.4 % on Au 0.02 Cu 2 O catalyst at a total current density of~5.7 mA•cm À 2 at À 1.3 V (Table S3), 4 times that of single Cu 2 O, while CH 4 generation was remarkably suppressed. This result means C 2 H 4 production accounted for ~43 % of the total carbonaceous gas products.…”

Elucidating the structure-dependent selectivity of CuZn towards methane and ethanol in CO2 electroreduction using tailored Cu/ZnO precatalysts

“…1 However, the progress toward obtaining them with high selectivity remains limited compared to that made in the production of gaseous hydrocarbon products. 2 Copper is the only single metal capable of producing products beyond CO, including alcohols. 1,2 While this catalyst holds record efficiencies towards methane and ethylene, its lower selectivity toward ethanol is attributed to the higher energy barrier of ethanol formation with respect to ethylene, whose pathway shares common intermediates with the former.…”

“…1,2 Tandem schemes and modification of the electronic properties of copper achieved by coupling it with a second element are a promising strategy to improve its selectivity towards alcohols, particularly ethanol. [2][3][4][5][6][7][8][9][10] Most of the studies so far have focused on the composition dependence of the catalytic behaviour. [2][3][4][5][6][7][8][9][10] However, the sensitivity of the catalytic performance to the atomic distribution within bimetallic catalysts remains largely underexplored.…”

Advancing the Anode Compartment for Energy Efficient CO2 Reduction at Neutral pH

“…The oxygen evolution reaction (OER) is the most prevalent anode reaction for electrochemical CO 2 conversion -this exciting approach can sustainably generate valuable energy-rich products using intermittent renewable electricity sources. [1][2][3][4] Although most studies focus on the optimisation of the cathode compartment, the anode is key to the development of an economically viable technology. Here we discuss the improvement of a CO 2 -reduction electrolyser design from the anode perspective, a standpoint which is often overlooked.…”