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 article , the authors present a critical overview of recent advances in experimental design and simulation of MEAs for CO2 reduction reaction, including the shortcomings and remedial strategies, and the remaining challenges and future research opportunities are suggested to support the advancement of CO2 electrochemical technologies.
Abstract: CO2 electrochemical reduction reaction (CO2RR) enables conversion of greenhouse gas CO2 into value-added products, which simultaneously reduces carbon emissions and reduces the usage of fossil fuels as feed materials to produce fuel/chemical products. It also provides the potential to integrate electrocatalytic processes with electricity from renewable sources for storing renewable energy. Membrane-electrode assemblies (MEAs) can be an efficient solution to address the key issues in aqueous electrolyzer design and enable the industrial scale-up. In this paper, we reviewed recent advances in the experimental design and simulation of MEAs. The discussion of existing challenges and future research priorities for guiding MEA development and understanding reaction mechanism is also provided. Electrochemical conversion of gaseous CO2 to value-added products and fuels is a promising approach to achieve net-zero CO2 emission energy systems. Significant efforts have been achieved in the design and synthesis of highly active and selective electrocatalysts for this reaction and their reaction mechanism. To perform an efficient conversion and desired product selectivity in practical applications, we need an active, cost-effective, stable, and scalable electrolyzer design. Membrane-electrode assemblies (MEAs) can be an efficient solution to address the key challenges in the aqueous gas diffusion electrodes (GDE), e.g., ohmic resistances and complex reactor design. This review presents a critical overview of recent advances in experimental design and simulation of MEAs for CO2 reduction reaction, including the shortcomings and remedial strategies. In the last section, the remaining challenges and future research opportunities are suggested to support the advancement of CO2 electrochemical technologies. Electrochemical conversion of gaseous CO2 to value-added products and fuels is a promising approach to achieve net-zero CO2 emission energy systems. Significant efforts have been achieved in the design and synthesis of highly active and selective electrocatalysts for this reaction and their reaction mechanism. To perform an efficient conversion and desired product selectivity in practical applications, we need an active, cost-effective, stable, and scalable electrolyzer design. Membrane-electrode assemblies (MEAs) can be an efficient solution to address the key challenges in the aqueous gas diffusion electrodes (GDE), e.g., ohmic resistances and complex reactor design. This review presents a critical overview of recent advances in experimental design and simulation of MEAs for CO2 reduction reaction, including the shortcomings and remedial strategies. In the last section, the remaining challenges and future research opportunities are suggested to support the advancement of CO2 electrochemical technologies. The availability and affordability of fossil fuels are the key issues for society in the present and future. Using fossil fuels also causes carbon emission problems. There is an increasingly urgent need to decouple carbon emissions from economic activity without stifling growth.1Chu S. Majumdar A. Opportunities and challenges for a sustainable energy future.Nature. 2012; 488: 294-303Google Scholar, 2Lackner K.S. Climate change. A guide to CO2 sequestration.Science. 2003; 300: 1677-1678Google Scholar, 3Otto A. Grube T. Schiebahn S. Stolten D. Closing the loop: captured CO2 as a feedstock in the chemical industry.Energy Environ. Sci. 2015; 8: 3283-3297Google Scholar, 4Müller L.J. Kätelhön A. Bringezu S. McCoy S. Suh S. Edwards R. Sick V. Kaiser S. Cuéllar-Franca R. 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Advances and challenges in electrochemical CO2 reduction processes: an engineering and design perspective looking beyond new catalyst materials.J. Mater. Chem. A. 2020; 8: 1511-1544Google Scholar Besides, other issues such as electrolyte consumption by CO2 and GDE flooding are effectively eliminated. Another important advantage of MEA reactors is their superior product and voltage stability as well as energy efficiency compared with electrolyte-flowing systems. MEA-type electrolyzers have not been extensively studied for multicarbon products and the formation of these products via more complex reactions requires more studies.60Sebastián D. Palella A. Baglio V. Spadaro L. Siracusano S. Negro P. Niccoli F. Aricò A.S. CO2 reduction to alcohols in a polymer electrolyte membrane co-electrolysis cell operating at low potentials.Electrochim. 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Continuous carbon dioxide electroreduction to concentrated multi-carbon products using a membrane electrode assembly.Joule. 2019; 3: 2777-2791Google Scholar Recently, Gu et al. used Cu catalysts with stepped sites with high surface coverages of ∗CO intermediates and the bridge-bound ∗CO adsorption, and it allowed to trigger CO2 reduction pathways toward the formation of alcohols.61Gu Z. Shen H. Chen Z. Yang Y. Yang C. Ji Y. Wang Y. Zhu C. Liu J. Li J. et al.Efficient electrocatalytic CO2 reduction to C2+ alcohols at defect-site-rich Cu surface.Joule. 2021; 5: 429-440Google Scholar In this study, electrochemical deposition of Cu under a CO-rich environment led to the fabrication of defective Cu surfaces via stabilizing the surface energy, and the defect-site-rich surfaces greatly enhance the CO2-to-alcohol reduction pathway. Using this defect-site-rich Cu catalyst, ∼70% FE toward C2+ alcohols with partial current densities of >100 mA cm−2 was achieved. In contrast to scarce multicarbon production on MEA-type electrolyzers, CO production has been one of the main targets of studies. Production of CO by using CO-selective Au and Ag electrocatalysts has been the main application of MEA systems for CO2RR.42Lee J.-H. Lim J. Roh C.-W. Whang H.S. Lee H. Electrochemical CO2 reduction using alkaline membrane electrode assembly on various metal electrodes.J. CO2 Util. 2019; 31: 244-250Google Scholar,45Fujinuma N. Ikoma A. Lofland S.E. Highly efficient electrochemical CO2 reduction reaction to CO with one-pot synthesized Co-pyridine-derived catalyst incorporated in a Nafion-based membrane electrode assembly.Adv. Energy Mater. 2020; 10: 2001645Google Scholar,46Lee W.H. Ko Y.-J. Choi Y. Lee S.Y. Choi C.H. Hwang Y.J. Min B.K. Strasser P. Oh H.-S. Highly selective and scalable CO2 to CO—electrolysis using coral-nanostructured Ag catalysts in zero-gap configuration.Nano Energy. 2020; 76: 105030https://doi.org/10.1016/j.nanoen.2020.105030Google Scholar,48Ham Y.S. Park Y.S. Jo A. Jang J.H. Kim S.-K. Kim J.J. Proton-exchange membrane CO2 electrolyzer for CO production using Ag catalyst directly electrodeposited onto gas diffusion layer.J. Power Sources. 2019; 437: 226898Google Scholar, 49Kutz R.B. Chen Q. Yang H. Sajjad S.D. Liu Z. Masel I.R. Sustainion imidazolium-functionalized polymers for carbon dioxide electrolysis.Energy Technol. 2017; 5: 929-936Google Scholar, 50Sato M. Ogihara H. Yamanaka I. Electrocatalytic reduction of CO2 to CO and CH4 by Co–N–C catalyst and Ni co-catalyst with PEM reactor.ISIJ Int. 2019; 59: 623-627Google Scholar, 51Ogihara H. Maezuru T. Ogishima Y. Inami Y. Saito M. Iguchi S. Yamanaka I. The active center of Co–N–C electrocatalysts for the selective reduction of CO2 to CO using a Nafion-H electrolyte in the gas p
43 citations
TL;DR: In this paper, a versatile nanoconfined ionic liquids (ILs) is proposed to enhance the electrocatalytic properties of single-atom catalysts, which is highly desirable, yet challenging.
Abstract: The development of strategies to enhance the electrocatalytic properties of single-atom catalysts is highly desirable, yet challenging. Here we show a versatile nanoconfined ionic liquids (ILs) des...
43 citations
TL;DR: In this article, the authors reviewed the recent advances on chemical conversion of CO2 into C2+ chemicals and fuels with wide practical applications, including important alcohols, acetic acid, dimethyl ether, olefins and gasoline.
43 citations
15 Sep 2020
TL;DR: In this paper, a zero-gap flow electrolyzer with a tin-coated gas diffusion electrode as the cathode was used to convert humidified gaseous CO2 to formate.
Abstract: A zero-gap flow electrolyzer with a tin-coated gas diffusion electrode as the cathode was used to convert humidified gaseous CO2 to formate. The influence of humidification, flow pattern and the type of membrane on the faradaic efficiency (FE), product concentration, and salt precipitation were investigated. We demonstrated that water management in the gas diffusion electrode was crucial to avoid flooding and (bi)carbonate precipitation, to uphold a high FE and formate concentration. Direct water injection was validated as a novel approach for water management. At 100 mA/cm2, direct water injection in combination with an interdigitated flow channel resulted in a FE of 80 % and a formate concentration of 65.4+/−0.3 g/l without salt precipitation for a prolonged CO2 electrolysis of 1 h. The use of bipolar membranes in the zero-gap configuration mainly produced hydrogen. These results are important for the design of commercial scale CO2 electrolyzers.
42 citations
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TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
146,533 citations
TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Abstract: We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices will be discussed. Our approach is stable, reliable, and minimizes the number of order ${\mathit{N}}_{\mathrm{atoms}}^{3}$ operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special ``metric'' and a special ``preconditioning'' optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calculations. It will be shown that the number of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order ${\mathit{N}}_{\mathrm{atoms}}^{2}$ scaling is found for systems containing up to 1000 electrons. If we take into account that the number of k points can be decreased linearly with the system size, the overall scaling can approach ${\mathit{N}}_{\mathrm{atoms}}$. We have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable. \textcopyright{} 1996 The American Physical Society.
81,985 citations
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Abstract: The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Bl\"ochl's projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addition, critical tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed core all electron methods. These tests include small molecules $({\mathrm{H}}_{2}{,\mathrm{}\mathrm{H}}_{2}{\mathrm{O},\mathrm{}\mathrm{Li}}_{2}{,\mathrm{}\mathrm{N}}_{2}{,\mathrm{}\mathrm{F}}_{2}{,\mathrm{}\mathrm{BF}}_{3}{,\mathrm{}\mathrm{SiF}}_{4})$ and several bulk systems (diamond, Si, V, Li, Ca, ${\mathrm{CaF}}_{2},$ Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.
57,691 citations
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.
Abstract: An improved way of estimating the local tangent in the nudged elastic band method for finding minimum energy paths is presented. In systems where the force along the minimum energy path is large compared to the restoring force perpendicular to the path and when many images of the system are included in the elastic band, kinks can develop and prevent the band from converging to the minimum energy path. We show how the kinks arise and present an improved way of estimating the local tangent which solves the problem. The task of finding an accurate energy and configuration for the saddle point is also discussed and examples given where a complementary method, the dimer method, is used to efficiently converge to the saddle point. Both methods only require the first derivative of the energy and can, therefore, easily be applied in plane wave based density-functional theory calculations. Examples are given from studies of the exchange diffusion mechanism in a Si crystal, Al addimer formation on the Al(100) surfa...
6,825 citations
TL;DR: This paper describes how accurate off-lattice ascent paths can be represented with respect to the grid points, and maintains the efficient linear scaling of an earlier version of the algorithm, and eliminates a tendency for the Bader surfaces to be aligned along the grid directions.
Abstract: A computational method for partitioning a charge density grid into Bader volumes is presented which is efficient, robust, and scales linearly with the number of grid points. The partitioning algorithm follows the steepest ascent paths along the charge density gradient from grid point to grid point until a charge density maximum is reached. In this paper, we describe how accurate off-lattice ascent paths can be represented with respect to the grid points. This improvement maintains the efficient linear scaling of an earlier version of the algorithm, and eliminates a tendency for the Bader surfaces to be aligned along the grid directions. As the algorithm assigns grid points to charge density maxima, subsequent paths are terminated when they reach previously assigned grid points. It is this grid-based approach which gives the algorithm its efficiency, and allows for the analysis of the large grids generated from plane-wave-based density functional theory calculations.
5,417 citations