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: It is reported that defective indium/indium oxide heterostructures selectively catalyze CO2 electroreduction into C1 products in a broad potential range from -0.7 to -1.2 V vs RHE in aqueous media with the faradaic efficiency approaching 100%.
Abstract: Electrochemical CO2 reduction to fuels and chemicals is a promising approach for CO2 utilization. Developing highly active, selective, and cost-effective electrocatalysts is the key to the large-scale application of this technology. Here, we report that defective indium/indium oxide heterostructures selectively catalyze CO2 electroreduction into C1 products in a broad potential range from -0.7 to -1.2 V vs RHE in aqueous media with the faradaic efficiency approaching 100%. This electrocatalyst enables an efficient CO2-to-formate conversion with excellent selectivity (up to 93%), activity (up to 50.8 mA cm-2), and durability (>25 h). The collaboration between metallic In and In oxide of the heterostructures attributes to the boosted electrochemical CO2 reduction: Metallic In mainly facilitates formate production, while In oxide suppresses the competing hydrogen evolution reaction. This study highlights the integration of different functional components/defects into heterostructures as an effective strategy for enhancing CO2 electrocatalysis.
30 citations
TL;DR: A core-shell-structured AgNW/NC700 composite using a Ag nanowire (NW) core encapsulated by a N-doped carbon (NC) shell at 700 °C developed might provide an alternative strategy for efficient electrochemical fixation of CO2.
Abstract: Numerous catalysts have been successfully introduced for CO2 fixation in aqueous or organic systems. However, a single catalyst showing activity in both solvent types is still rare, to the best of our knowledge. We developed a core-shell-structured AgNW/NC700 composite using a Ag nanowire (NW) core encapsulated by a N-doped carbon (NC) shell at 700 °C. Through control experiments and density functional theory calculations, it was confirmed that Ag nanowires acted as the active sites for CO2 fixation and the uniformly coating of N-doped carbon created a CO2 -rich environment around the Ag nanowires, which could significantly improve the catalytic activity of Ag nanowires for electrochemical CO2 fixation. Under mild conditions, up to 96 % faradaic efficiency of CO, 95 % yield of Ibuprofen and 92 % yield of propylene carbonate could be obtained in the electrochemical CO2 direct reduction, carboxylation and cycloaddition, respectively, using the same AgNWs/NC700 catalyst. These results might provide an alternative strategy for efficient electrochemical fixation of CO2 .
29 citations
TL;DR: In this article, a review reveals the origin of surface evolution, summarizes the general forms involving composition leaching, phase transformation, atom rearrangement, and metastable intermediate from typical electrocatalysts, and proposes control strategies toward the formation or reservation of stable highly active sites by atomic/defective modulation, interfacial coupling, structural optimization of pre-synthesis, and forming a protective layer.
29 citations
TL;DR: In this paper, the authors highlight the utilization of in situ spectroscopic methods that enhance our understanding of the CO2 reduction reaction and highlight the critical challenges associated with current state-of-the-art systems and insights on emerging prospects.
Abstract: Electrochemical reduction of CO2 to value-added chemicals and fuels is a promising approach to store renewable energy while closing the anthropogenic carbon cycle. Despite significant advances in developing new electrocatalysts, this system still lacks enough energy conversion efficiency to become a viable technology for industrial applications. To develop an active and selective electrocatalyst and engineer the reaction environment to achieve high energy conversion efficiency, we need to improve our knowledge of the reaction mechanism and material structure under reaction conditions. In situ spectroscopies are among the most powerful tools which enable measurements of the system under real conditions. These methods provide information about reaction intermediates and possible reaction pathways, electrocatalyst structure and active sites, as well as the effect of the reaction environment on products distribution. This review aims to highlight the utilization of in situ spectroscopic methods that enhance our understanding of the CO2 reduction reaction. Infrared, Raman, X-ray absorption, X-ray photoelectron, and mass spectroscopies are discussed here. The critical challenges associated with current state-of-the-art systems are identified and insights on emerging prospects are discussed.
29 citations
TL;DR: It is elucidate that product gaseous bubble accumulation on the electrode/electrolyte interface is the direct cause of the voltage instability in CO2 electrolyzers, and the strategic incorporation of the insights on bubble growth behavior and voltage instability is vital for designing commercially relevant CO2 electrodes.
29 citations
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