CO2 electroreduction to ethylene via hydroxide-mediated copper catalysis at an abrupt interface
18 May 2018-Science (American Association for the Advancement of Science)-Vol. 360, Iss: 6390, pp 783-787
TL;DR: A copper electrocatalyst at an abrupt reaction interface in an alkaline electrolyte reduces CO2 to ethylene with 70% faradaic efficiency at a potential of −0.55 volts versus a reversible hydrogen electrode (RHE).
Abstract: Carbon dioxide (CO 2 ) electroreduction could provide a useful source of ethylene, but low conversion efficiency, low production rates, and low catalyst stability limit current systems. Here we report that a copper electrocatalyst at an abrupt reaction interface in an alkaline electrolyte reduces CO 2 to ethylene with 70% faradaic efficiency at a potential of −0.55 volts versus a reversible hydrogen electrode (RHE). Hydroxide ions on or near the copper surface lower the CO 2 reduction and carbon monoxide (CO)–CO coupling activation energy barriers; as a result, onset of ethylene evolution at −0.165 volts versus an RHE in 10 molar potassium hydroxide occurs almost simultaneously with CO production. Operational stability was enhanced via the introduction of a polymer-based gas diffusion layer that sandwiches the reaction interface between separate hydrophobic and conductive supports, providing constant ethylene selectivity for an initial 150 operating hours.
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TL;DR: In this paper, a thin film comprised of alloyed Cr and Ga oxides on glassy carbon is shown to electrocatalytically generate oxalate from aqueous CO2 with high Faradaic efficiencies at 690 mV overpotential.
Abstract: Electrochemical transformation of CO2 into commodity chemicals such as oxalate is a strategy for profitably remediating high atmospheric CO2 levels. Electrocatalysts for oxalate generation, however, have required prohibitively large applied potentials, forcing the use of nonaqueous electrolytes. Here, a thin film comprised of alloyed Cr and Ga oxides on glassy carbon is shown to electrocatalytically generate oxalate from aqueous CO2 with high Faradaic efficiencies at 690 mV overpotential. Oxalate is produced at a surface anion site via a CO-dependent pathway; the process is highly sensitive to the hydrogen-bonding environment and avoids the commonly invoked CO2•– intermediate. Ultimately, this catalytic system accomplishes efficient CO2 to oxalate conversion in protic electrolyte.
35 citations
TL;DR: In this article, a novel copper-poly(ionic liquid) (Cu@PIL) hybrid was proposed to achieve multi-electron reduction with current densities ≥ 300 µm cm−2, where the ionic pairs in the outer PIL layer enrich local CO2 concentration, thereby promoting the CO2 supply.
Abstract: Ionic liquid-based electrocatalytic CO2 reduction faces the challenge of achieving high selectivity toward value-added C2+ products at high reaction rate (≥ 100 mA cm−2). Herein, novel copper@poly(ionic liquid) (Cu@PIL) hybrids demonstrate multi-electron reduction (> 2e–) with current densities ≥ 300 mA cm−2. Remarkably, Cu@PIL with F– anion exhibits high C2+ faradaic efficiency of 58 % with a high partial current density of 174 mA cm−2. Further, a highest C2+ partial current density of 233 mA cm−2 was also achieved. Experimental combined theoretical investigations reveal that the “individual” ionic pairs in the outer PIL layer enrich local CO2 concentration, thereby promoting the CO2 supply. Besides, an interfacial electric field is induced by the unbonded imidazolium moieties at Cu-PIL interface, which stabilize intermediates. Anions, differing in the electron-donating number to the imidazolium moieties, influence both the enrichment of CO2 and the stabilization of intermediates, thus regulating current density and product selectivity.
35 citations
TL;DR: It is demonstrated that the reaction of *CO and *CHO is the key process for obtaining the C2 products on the Cu/Au interface, and a useful strategy for improving the surface activity and selectivity for CO2RR is offered.
Abstract: Understanding the bimetallic interfacial effects on the catalytic CO2 reduction reaction (CO2RR) is an important and challenging issue. Herein, the geometric structure, electronic structure, and electrocatalytic property of Cu(submonolayer)/Au bimetallic interfaces are investigated by using density functional theory calculation. The results predict that the expansion of the Cu lattice can significantly modulate the CO2RR performance, the Cu(submonolayer)/Au interface has good surface activity promoting the reduction of CO2 to C2 compounds, and the final products of CO2RR on Cu/Au(111) and Cu/Au(100) surfaces are ethanol and a mixture of ethanol and ethylene, respectively. Furthermore, with regard to surface coverage and adsorption energy being two essential parameters for CO2RR, we demonstrate that the reaction of *CO and *CHO is the key process for obtaining the C2 products on the Cu/Au interface. This study offers a useful strategy for improving the surface activity and selectivity for CO2RR.
35 citations
TL;DR: In this paper, a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edge via a facile bottom-up strategy was fabricated, facilitating the efficient surface absorption of CO2 and lowering the CO2 transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at Fermi level.
Abstract: The reduction of CO2 into C1 feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO2 is achieving high conversion efficiency due to the high CO dissociation energy of CO2 and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edge via a facile bottom-up strategy, facilitating the efficient surface absorption of CO2 and lowering the CO2 transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO2 molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 μmol h−1 g−1 in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO2 and broadband spectral response for the efficient photocatalytic reduction of CO2.
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TL;DR: An improved way of estimating the local tangent in the nudged elastic band method for finding minimum energy paths is presented, and examples given where a complementary method, the dimer method, is used to efficiently converge to the saddle point.
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5,417 citations