Metal organic framework-ionic liquid hybrid catalysts for the selective electrochemical reduction of CO2 to CH4 (original) (raw)
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Efficient electro-reduction of CO 2 over metal−organic framework (MOF) materials is hindered by the poor contact between thermally synthesized MOF particles and the electrode surface, which leads to low Faradaic efficiency for a given product and poor electrochemical stability of the catalyst. We report a MOFbased electrode prepared via electro-synthesis of MFM-300(In) on an indium foil, and its activity for the electrochemical reduction of CO 2 is assessed. The resultant MFM-300(In)-e/In electrode shows a 1 order of magnitude improvement in conductivity compared with that for MFM-300(In)/carbon-paper electrodes. MFM-300(In)-e/In exhibits a current density of 46.1 mA cm −2 at an applied potential of −2.15 V vs Ag/Ag + for the electro-reduction of CO 2 in organic electrolyte, achieving an exceptional Faradaic efficiency of 99.1% for the formation of formic acid. The facile preparation of the MFM-300(In)-e/In electrode, coupled with its excellent electrochemical stability, provides a new pathway to develop efficient electro-catalysts for CO 2 reduction.
Communications Chemistry
The development of efficient CO2 capture and utilization technologies driven by renewable energy sources is mandatory to reduce the impact of climate change. Herein, seven imidazolium-based ionic liquids (ILs) with different anions and cations were tested as catholytes for the CO2 electrocatalytic reduction to CO over Ag electrode. Relevant activity and stability, but different selectivities for CO2 reduction or the side H2 evolution were observed. Density functional theory results show that depending on the IL anions the CO2 is captured or converted. Acetate anions (being strong Lewis bases) enhance CO2 capture and H2 evolution, while fluorinated anions (being weaker Lewis bases) favour the CO2 electroreduction. Differently from the hydrolytically unstable 1-butyl-3-methylimidazolium tetrafluoroborate, 1-Butyl-3-Methylimidazolium Triflate was the most promising IL, showing the highest Faradaic efficiency to CO (>95%), and up to 8 h of stable operation at high current rates (−20 ...
ACS Sustainable Chemistry & Engineering, 2019
The electrochemical reduction of carbon dioxide (ECR-CO 2) to produce low 2 carbon fuels and high-value industrial chemicals has been proven to be a viable solution to 3 energy sustainability. However, the energy efficiency of electrocatalytic CO 2 reduction is 4 seriously limited by both the poor electrocatalyst with insufficient activity, selectivity and 5 stability, and ineffective electrochemical reactors. In this work, the electroreduction of CO 2 6 to CO is highly improved by the design of copper metal organic frameworks-derived 7 nanoparticle (Cu-MOF/NP) catalysts, in which Cu/Cu 2 O particles form a porous octahedral 8 structure containing tunable Cu 0 and Cu + catalytic active sites. The ECR-CO 2 can be 9 realized with a high current density of 25.15 mA cm-2 at a very low applied potential of 10 merely 0.79V RHE even in H-type cell, owing to the high-surface-area porous structure with 11 optimal surface chemistry of exposed Cu cations. Notably, a new flow electrochemical 12 reactor integrating with a membrane electrode assembly (MEA) is designed to not only 13 largely reduce the applied potential (200mV), but also prompt the sensitivity of the reactor 14 for identifying and quantifying reaction products. Accordingly, the Cu-MOF/NP catalyst 15 enables an ultrahigh current density beyond 230 mA cm-2 at a low applied potential of-16 0.86V RHE in the flow MEA reactor, and the ethanol product (often undetectable in the 17 traditional H-type cell) can be harvested.
Principal Descriptors of Ionic Liquid Co-catalysts for the Electrochemical Reduction of CO2
ACS applied energy materials, 2020
Electrochemical reduction of carbon dioxide (CO RR) is promoted by ionic liquid (IL) cocatalysts and several mechanisms have been proposed to explain their role. Due to the complexity of the CO 2 RR, and the limited number of active IL co-catalysts, a consensus on the precise role of ILs has not been reached and it is not possible to improve their activity in a rational way. Herein, we describe guanidinium (Gua) ILs that act as cocatalysts for the CO 2 RR when employed in non-aqueous electrolytes. The peripheral substituents of the Gua cation were systematically modified allowing the IL co-catalytic properties to be fine-tuned, and on the basis of the observed substitution effects, charge delocalization and availability were shown to be the critical descriptors determining cocatalytic activity. These descriptors can be used to rationalize activity trends for other classes of IL co-catalysts.
Metal−Organic Framework Based Single-Atom Catalysts for Electrochemical CO 2 Sequestration
Single-atom catalysts are promising heterogeneous catalysts, having significant characteristics including selectivity, stability, and higher atomic efficiency. The maximized atomic efficiency and geometric and electronic structures of single- atom catalysts has led to broader applications including electrochemical CO2 reduction. Single-atom catalytic approaches overcome the size-dependent limitation of nanosized electrocatalysts and lead to desired and selective reactions. In addition, the development of metal-organic frameworks is being recognized as a promising precursor for the fabrication of single-atom catalysts and has been reported as advantageous for electrochemical applications. However, studies on the controlled synthesis and mechanistic research approaches are still required for the development of single-atom catalysts to improve electrochemical CO2 sequestration.
Journal of Electronic Materials, 2019
Fuel cells and metal-air batteries have been comprehensively investigated in recent years because of their high energy capacity, good efficiency and environmental friendly nature. Slow kinetics of oxygen reduction reaction (ORR), one of the main processes in fuel cells and metal-air batteries, is improved with platinum catalysts that confine the prevalent utilization of such electrochemical devices with increasing worth for them. However, platinum catalysts after long time usage exhibit weak operations due to the crossover effect and agglomeration. Metal-organic frameworks (MOFs), the porous crystalline materials, consisting of metal centers coordinated to organic ligands, are appropriate catalysts due to their superior properties such as high surface area and carbon content, tunable pore size and diverse metal nodes. In this review, we summarize the recent progress in synthesis and design of MOFderived ORR electrocatalysts in acidic and alkaline fuel cells. Our focus is on the different methods developed for improving the activity and stability of MOF based ORR electrocatalysts.
Nature Communications, 2020
Highly effective electrocatalysts promoting CO2 reduction reaction (CO2RR) is extremely desirable to produce value-added chemicals/fuels while addressing current environmental challenges. Herein, we develop a layer-stacked, bimetallic two-dimensional conjugated metal-organic framework (2D c-MOF) with copper-phthalocyanine as ligand (CuN4) and zinc-bis(dihydroxy) complex (ZnO4) as linkage (PcCu-O8-Zn). The PcCu-O8-Zn exhibits high CO selectivity of 88%, turnover frequency of 0.39 s−1 and long-term durability (>10 h), surpassing thus by far reported MOF-based electrocatalysts. The molar H2/CO ratio (1:7 to 4:1) can be tuned by varying metal centers and applied potential, making 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; ZnO4 complexes act as CO2RR catalytic sites while CuN4 centers promote the protonation of adsorbed CO2 during CO2RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO2RR toward syngas synthesis.
Small
The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202100762\. conversion are potential methods to lower CO 2 concentration in the atmosphere. [2-4] In contrast to CO 2 capture, CO 2 conversion is more promising, as it can convert CO 2 into low-carbon fuels or other valuable chemicals such as CO, CH 4 , HCOOH, and C 2 H 5 OH. [5-8] Importantly, for industrial applications, CO 2 reduction reaction (CO 2 RR) is considered to be a practical and potentially valuable method for the generation of clean, renewable energy that can be undertaken even at room temperature and ambient pressure. [9-13] Given the high thermodynamic stability, the low electron affinity of CO 2 molecules, and the competitive reaction of hydrogen evolution in the formation of the desired products, a highly selective and efficient catalyst for CO 2 RR is urgently needed. [14-21] In recent years, metal-organic frameworks (MOFs) composed of various transition metals ions and organic linkers have emerged in the field of electrocatalysis. [22,23] Compared with noble metals, transition metal chalcogenides, and other catalytic materials, MOFs feature very large specific surface
Molecules, 2021
The electrochemical reduction of carbon dioxide (CO2ER) is amongst one the most promising technologies to reduce greenhouse gas emissions since carbon dioxide (CO2) can be converted to value-added products. Moreover, the possibility of using a renewable source of energy makes this process environmentally compelling. CO2ER in ionic liquids (ILs) has recently attracted attention due to its unique properties in reducing overpotential and raising faradaic efficiency. The current literature on CO2ER mainly reports on the effect of structures, physical and chemical interactions, acidity, and the electrode–electrolyte interface region on the reaction mechanism. However, in this work, new insights are presented for the CO2ER reaction mechanism that are based on the molecular interactions of the ILs and their physicochemical properties. This new insight will open possibilities for the utilization of new types of ionic liquids. Additionally, the roles of anions, cations, and the electrodes in...