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: Copper is the only pure metal electrocatalyst capable of converting carbon dioxide to hydrocarbons at significant reaction rates as mentioned in this paper, but the product selectivity of this process on copper is poor.
Abstract: Copper is the only pure metal electrocatalyst capable of converting carbon dioxide to hydrocarbons at significant reaction rates. However, the poor product selectivity of this process on copper rem...
36 citations
TL;DR: A two-step approach to achieve intimate atomic Cu-Ag interfaces on the surface of Cu nanowires, which showed greatly improved CO2RR selectivity towards methane (CH4) was proposed in this article.
Abstract: Developing highly efficient electrochemical catalysts for carbon dioxide reduction reaction (CO2RR) provides a solution to battle global warming issues resulting from ever-increasing carbon footprint due to human activities. Copper (Cu) is known for its efficiency in CO2RR towards value-added hydrocarbons; hence its unique structural properties along with various Cu alloys have been extensively explored in the past decade. Here, we demonstrate a two-step approach to achieve intimate atomic Cu-Ag interfaces on the surface of Cu nanowires, which show greatly improved CO2RR selectivity towards methane (CH4). The specially designed Cu-Ag interfaces showed an impressive maximum Faradaic efficiency (FE) of 72% towards CH4 production at −1.17 V (vs. reversible hydrogen electrode (RHE)).
36 citations
TL;DR: In this paper, a 2D transport model for a gas diffusion electrode performing CO₂ reduction to CO with a flowing catholyte is presented, including the concentration gradients along the flow cell, spatial distribution of the current density and local pH in the catalyst layer.
Abstract: Results of a 2-D transport model for a gas diffusion electrode performing CO₂ reduction to CO with a flowing catholyte are presented, including the concentration gradients along the flow cell, spatial distribution of the current density and local pH in the catalyst layer. The model predicts that both the concentration of CO₂ and the buffer electrolyte gradually diminish along the channels for a parallel flow of gas and electrolyte as a result of electrochemical conversion and nonelectrochemical consumption. At high single-pass conversions, significant concentration gradients exist along the flow channels leading to large local variations in the current density (>150 mA/cm²), which becomes prominent when compared to ohmic losses. In addition, concentration overpotentials change dramatically with CO₂ flow rate, which results in significant differences in outlet concentrations at high conversions. The outlet concentration of CO attains a maximum of 80% along with 5% CO₂ and 15% H₂, although the maximum single-pass conversion is limited to below 60% due to homogeneous consumption by the electrolyte. Fundamental and practical implications of our findings on electrochemical CO₂ reduction are discussed with a focus on the trade-off between high current density operation and high single-pass conversion efficiency.
36 citations
TL;DR: In this article, a comprehensive analysis on the interplays between the above catalyst-dynamic-changes/reaction environments and the CO2 reduction performance is rare, if not none, and some perspectives on future investigations are offered with the aim of understanding the origins of the effects from the catalyst dynamic changes and the reaction environments.
Abstract: Electrochemical reduction of carbon dioxide (CO2 ) is substantially researched due to its potential for storing intermittent renewable electricity and simultaneously helping mitigating the pressing CO2 emission concerns. The major challenge of electrochemical CO2 reduction lies on having good controls of this reaction due to its complicated reaction networks and its unusual sensitivity to the dynamic changes of the catalyst structure (chemical states, compositions, facets and morphology, etc.), and to the non-catalyst components at the electrode/electrolyte interface, in another word the reaction environments. To date, a comprehensive analysis on the interplays between the above catalyst-dynamic-changes/reaction environments and the CO2 reduction performance is rare, if not none. In this review, the catalyst dynamic changes observed during the catalysis are discussed based on the recent reports of electrochemical CO2 reduction. Then, the above dynamic changes are correlated to their effects on the catalytic performance. The influences of the reaction environments on the performance of CO2 reduction are also discussed. Finally, some perspectives on future investigations are offered with the aim of understanding the origins of the effects from the catalyst dynamic changes and the reaction environments, which will allow one to better control the CO2 reduction toward the desired products.
36 citations
TL;DR: Converting CO2 into value-added fuels or chemical feedstocks through electrochemical reduction is one of the several promising avenues to reduce atmospheric carbon dioxide levels and alleviate global warming.
Abstract: Converting CO2 into value-added fuels or chemical feedstocks through electrochemical reduction is one of the several promising avenues to reduce atmospheric carbon dioxide levels and alleviate global warming. This approach has mild operating conditions, adjusts product distribution, allows modular design, and offers opportunities for carbon-intensive manufacturing industries to utilize renewable energy power for CO2 reduction. In recent decades, various valid methods and strategies have been developed for high efficiency and high selectivity electrocatalysts to reduce CO2. Unfortunately, while intensive research focuses on the development of new electrocatalysts, little attention has been paid to the engineering design of low-cost and large-scale CO2 reduction electrolyzer architectures, which impairs the full realization of potential benefits of new electrocatalysts. This review summarizes the recent progress of reactor architectures and system engineering in the CO2 reduction reaction. We discuss how to improve the performance of the CO2 reduction reaction from four aspects: (i) flow cell architectures, (ii) management of reactant delivery, (iii) membranes, and (iv) electrolytes. We aim to introduce reactor architectures and system engineering strategies in detail to enable further development and provide inspiration for potential industrial applications of CO2 reduction.
36 citations
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