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, the authors provide a critical review on recent advances in photocatalytic and electrocatalytic conversions of major C1 molecules, including CO, CO2, CH4, CH3OH and HCHO, into value-added multi-carbon (C2+) compounds.
Abstract: Selective transformation of one-carbon (C1) molecules, which are abundant or easily available and inexpensive carbon feedstocks, into value-added multi-carbon (C2+) compounds is a very attractive but highly challenging research target. Photocatalysis and electrocatalysis have offered great opportunities for the activation and controllable C–C coupling of C1 molecules under mild and environmentally benign conditions. This article provides a critical review on recent advances in photocatalytic and electrocatalytic conversions of major C1 molecules, including CO, CO2, CH4, CH3OH and HCHO, into C2+ compounds, such as C2H4, C3H6, ethanol and ethylene glycol, which play essential roles in the current chemical or energy industry. Besides the photocatalysts and electrocatalysts reported for these conversions, the structure–performance relationships and the key factors that control the activity and product selectivity are analysed to provide insights into the rational design of more efficient catalysts for the synthesis of C2+ compounds from C1 feedstocks. The active species, reaction intermediates and reaction or catalyst-functioning mechanism are discussed to deepen the understanding of the chemistry for the activation and selective C–C coupling of C1 molecules in the presence of solar energy or electrical energy.
83 citations
TL;DR: In this article, a review of recent advances of graphene-based catalysts in electrocatalytic CO2 reduction is presented, where the relationship between structure and property with regard to CO2 electroreduction is highlighted.
Abstract: Electrocatalytic CO2 reduction (ECR) using renewable electricity provides an alternative strategy for alleviating energy shortage and global warming issues. To facilitate this kinetically sluggish process, the design of highly selective, energy-efficient, and cost-effective electrocatalysts is key. Graphene-based materials have features of relatively low cost, excellent electrical conductivity, tunability in structure and surface chemistry, and renewability, rendering them competitive for CO2 electroreduction. In particular, by doping with heteroatoms, it’s possible to create unique active sites on graphene for CO2 adsorption and activation. Besides, integration of graphene with other materials enables creation of a synergistic effect, thereby boosting CO2 conversion. This review focuses on recent advances of graphene-based catalysts in ECR. The relationship between structure and property with regard to CO2 electroreduction is highlighted. Leading electrocatalysts are discussed and compared with some metal benchmark materials to provide an evolutionary perspective of performance progress. Development opportunities and challenges in the field are also summarized.
83 citations
TL;DR: In this article, the application of Cu oxides/ZnO-based electrocatalytic surfaces for the continuous and selective gas-phase electroreduction of CO2 to ethylene in a filter-press type electrochemical cell is studied.
Abstract: In this work, the application of Cu oxides/ZnO-based electrocatalytic surfaces for the continuous and selective gas-phase electroreduction of CO2 to ethylene in a filter-press type electrochemical cell is studied. The prepared catalytic materials are characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Then, the Cu oxides/ZnO-based gas diffusion electrodes are electrochemically characterized by cyclic voltammetry and Tafel plot analyses. The ethylene formation rate and Faradaic efficiency are as high as 487.9 μmol m−2s−1 and 91.1% when a current density of 7.5 mAcm−2 (-2.5 V vs. Ag/AgCl) is applied to the system, with an ethylene/methane production ratio of 139, showing a better performance than previous electrocatalytic systems for the production of ethylene from CO2 conversion. Consequently, the use of Cu oxides/ZnO-based electrocatalysts for gas-phase CO2 reduction is a step forward in the production of C2 products, such as ethylene.
83 citations
TL;DR: In this paper, the authors reported a highly active CO2 reduction reaction (CO2RR) catalyst, namely Co-N-Ni/NPCNSs, which is considered as an advanced single-site catalyst with Co−N−Ni bimetallic sites connected by a N bridge between Co and Ni.
Abstract: The electrochemical CO2 reduction reaction (CO2RR) is of importance for reducing global CO2 emissions. Herein, we reported a highly active CO2RR catalyst, namely Co–N–Ni/NPCNSs, which is considered as an advanced single-site catalyst with Co–N–Ni bimetallic sites connected by a N bridge between Co and Ni. The N-bridged Co–N–Ni bimetallic sites were confirmed by the X-ray absorption spectroscopy. The Co–N–Ni/NPCNSs catalyst shows a higher turnover frequency of 2049 h−1 at a low overpotential of 370 mV and CO faradaic efficiency of 96.4% compared to that of Co–N/NPCNSs (1205 h−1 and 61.5%) and Ni–N/NPCNSs (404 h−1 and 45.0%) with single Co–N4 and Ni–N4 sites, respectively. In situ synchrotron radiation Fourier transform infrared spectra and DFT calculations show that N-bridged Co–N–Ni bimetallic sites promote the formation of COOH* intermediates, thus accelerating CO2RR.
82 citations
TL;DR: In this paper, a single-atom surface alloys with high surface densities (up to 8%) are anchored on the Cu host for efficient electrocatalytic CO2 reduction.
Abstract: Direct experimental observations of the interface structure can provide vital insights into heterogeneous catalysis. Examples of interface design based on single atom and surface science are, however, extremely rare. Here, we report Cu–Sn single-atom surface alloys, where isolated Sn sites with high surface densities (up to 8%) are anchored on the Cu host, for efficient electrocatalytic CO2 reduction. The unique geometric and electronic structure of the Cu–Sn surface alloys (Cu97Sn3 and Cu99Sn1) enables distinct catalytic selectivity from pure Cu100 and Cu70Sn30 bulk alloy. The Cu97Sn3 catalyst achieves a CO Faradaic efficiency of 98% at a tiny overpotential of 30 mV in an alkaline flow cell, where a high CO current density of 100 mA cm−2 is obtained at an overpotential of 340 mV. Density functional theory simulation reveals that it is not only the elemental composition that dictates the electrocatalytic reactivity of Cu–Sn alloys; the local coordination environment of atomically dispersed, isolated Cu–Sn bonding plays the most critical role. The understanding of catalytic reactions at the atomic interface is vital; however, the characterization and mechanism studies of atomically dispersed catalysts remain challenging. Here, the authors demonstrate Cu–Sn surface alloys with isolated Sn atoms on a Cu host to achieve efficient CO2 to CO conversion.
82 citations
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