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1.
We present surface reconstruction-induced C−C coupling whereby CO2 is converted into ethylene. The wurtzite phase of CuGaS2. undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO2 to ethylene (C2H4). Upon illumination, the catalyst efficiently converts CO2 to C2H4 with 75.1 % selectivity (92.7 % selectivity in terms of Relectron) and a 20.6 μmol g−1 h−1 evolution rate. Subsequent spectroscopic and microscopic studies supported by theoretical analysis revealed operando-generated Cu2+, with the assistance of existing Cu+, functioning as an anchor for the generated *CO and thereby facilitating C−C coupling. This study demonstrates strain-induced in situ surface reconstruction leading to heterojunction formation, which finetunes the oxidation state of Cu and modulates the CO2 reduction reaction pathway to selective formation of ethylene.  相似文献   

2.
Electrochemical CO2 reduction reaction (CO2RR) over Cu catalysts exhibits enormous potential for efficiently converting CO2 to ethylene (C2H4). However, achieving high C2H4 selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO2RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu-based material to a pathway that facilitates CO2 reduction to C2H4 products. An excellent Faraday efficiency (FE) of 63.6 % on C2H4 with a current density of 497.2 mA cm−2 in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH4. The in situ X-ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cuδ+ during the CO2RR. Furthermore, theoretical calculations demonstrate that the Cuδ+/Cu0 interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C2H4 production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO2 reduction to value-added chemicals.  相似文献   

3.
The effects of separate C2H4/O2 feed and C2H4 feed position on the ethylene epoxidation reaction in an AC cylindrical dielectric barrier discharge reactor were investigated. The highest EO selectivity of 34?% and EO yield of 7.5?%, as well as the lowest power consumption of 1.72?×?10?16 Ws/molecule of EO produced, were obtained at a C2H4 feed position of 0.25, an O2/C2H4 feed molar ratio of 1/4, an applied voltage of 13?kV, an input frequency of 550?Hz, and a total feed flow rate of 75?cm3/min. The results demonstrated, for the first time, that the separate feed of C2H4 and O2 could provide better ethylene epoxidation performance in terms of higher EO selectivity and yield, and lower power consumption, as compared to the mixed feed. All undesired reactions including C2H4 cracking, dehydrogenation, oxidation, and coupling reactions are lowered by the ethylene separate feed because of a decrease in opportunity of ethylene molecules to be activated by generated electrons.  相似文献   

4.
Revealing the dynamic reconstruction process and tailoring advanced copper (Cu) catalysts is of paramount significance for promoting the conversion of CO2 into ethylene (C2H4), paving the way for carbon neutralization and facilitating renewable energy storage. In this study, we initially employed density functional theory (DFT) and molecular dynamics (MD) simulations to elucidate the restructuring behavior of a catalyst under electrochemical conditions and delineated its restructuring patterns. Leveraging insights into this restructuring behavior, we devised an efficient, low-coordination copper-based catalyst. The resulting synthesized catalyst demonstrated an impressive Faradaic efficiency (FE) exceeding 70 % for ethylene generation at a current density of 800 mA cm−2. Furthermore, it showed robust stability, maintaining consistent performance for 230 hours at a cell voltage of 3.5 V in a full-cell system. Our research not only deepens the understanding of the active sites involved in designing efficient carbon dioxide reduction reaction (CO2RR) catalysts but also advances CO2 electrolysis technologies for industrial application.  相似文献   

5.
In this work, ethylene epoxidation was investigated in a dielectric barrier discharge jet (DBDJ) with a separate ethylene/oxygen feed under oxygen lean conditions. The ethylene (C2H4) stream was directly injected behind the plasma zone in order to reduce all undesired reactions, including C2H4 cracking and further reactions, while the oxygen (O2) balanced with argon was fed through the plasma zone totally to maximize the formation of active oxygen species. The effects of various operating parameters, such as total feed flow rate, O2/C2H4 feed molar ratio, applied voltage, input frequency, and C2H4 feed position on the ethylene epoxidation activity, were investigated to determine the optimum operating conditions for this new DBDJ system. The highest ethylene oxide (EO) selectivity (55.2 %) and yield (27.6 %), as well as the lowest power consumption (3.3 × 10?21 and 6.0 × 10?21 Ws/molecule C2H4 converted and EO produced, respectively) were obtained at a total feed flow rate of 1,625 cm3/min (corresponding to a residence time of 0.022 s), an O2/C2H4 feed molar ratio of 0.25:1, an applied voltage of 9 kV, an input frequency of 300 Hz, and a C2H4 feed position of 3 mm behind the plasma zone. The superior activity of the ethylene epoxidation in the DBDJ system resulted from a small reaction volume as well as a separate ethylene/oxygen feed.  相似文献   

6.
Use of multi-metallic catalysts to enhance reactions is an interesting research area, which has attracted much attention. In this work, we carried out the first work to prepare trimetallic electrocatalysts by a one-step co-electrodeposition process. A series of Cu–X–Y (X and Y denote different metals) catalysts were fabricated using this method. It was found that Cu10La1Cs1 (the content ratio of Cu2+, La3+, and Cs+ in the electrolyte is 10 : 1 : 1 in the deposition process), which had an elemental composition of Cu10La0.16Cs0.14 in the catalyst, formed a composite structure on three dimensional (3D) carbon paper (CP), which showed outstanding performance for CO2 electroreduction reaction (CO2RR) to produce ethylene (C2H4). The faradaic efficiency (FE) of C2H4 could reach 56.9% with a current density of 37.4 mA cm−2 in an H-type cell, and the partial current density of C2H4 was among the highest ones up to date, including those over the catalysts consisting of Cu and noble metals. Moreover, the FE of C2+ products (C2H4, ethanol, and propanol) over the Cu10La1Cs1 catalyst in a flow cell reached 70.5% with a high current density of 486 mA cm−2. Experimental and theoretical studies suggested that the doping of La and Cs into Cu could efficiently enhance the reaction efficiency via a combination of different effects, such as defects, change of electronic structure, and enhanced charge transfer rate. This work provides a simple method to prepare multi-metallic catalysts and demonstrates a successful example for highly efficient CO2RR using non-noble metals.

Trimetallic Cu10La1Cs1 catalysts prepared via a one-step co-electrodeposition strategy can act as a robust electrocatalyst for CO2RR to C2H4.  相似文献   

7.
The efficient ethanol electrosynthesis from CO2 is challenging with low selectivity at high CO2 electrolysis rates, due to the competition with H2 and other reduction products. Copper-based bimetallic electrocatalysts are potential candidates for the CO2-to-ethanol conversion, but the secondary metal has mainly been focused on active components (such as Ag, Sn) for CO2 electroreduction, which also promote selectivity of ethylene or other reduction products rather than ethanol. Limited attention has been given to alkali-earth metals due to their inherently active chemical property. Herein, we rationally synthesized a (111) facet-oriented nano Cu2Mg (designated as Cu2Mg(111)) intermetallic compound with high-density ordered Cu3-Mg sites. The in situ Raman spectroscopy and density function theory calculations revealed that the Cu3 -Mg + active sites allowed to increase *CO surface coverage, decrease reaction energy for *CO−CO coupling, and stabilize *CHCHOH intermediates, thus promoting the ethanol formation pathway. The Cu2Mg(111) catalyst exhibited a high FEC2H5OH of 76.2±4.8 % at 600 mA⋅cm−2, and a peak value of |jC2H5OH| of 720±34 mA⋅cm−2, almost 4 times of that using conventional Cu2Mg with (311) facets, comparable to the best reported values for the CO2-to-ethanol electroreduction.  相似文献   

8.
The electrocatalytic reduction of carbon dioxide provides a feasibility to achieve a carbon-neutral energy cycle. However, there are a number of bottleneck issues to be resolved before industrial application, such as the low conversion efficiency, selectivity and reaction rate, etc. Engineering local environment is a critical way to address these challenges. Here, a monolayer MgAl-LDH was proposed to optimize the local environment of Cu for stimulating industrial-current-density CO2-to-C2H4 electroreduction in neutral media. In situ spectroscopic results and theoretical study demonstrated that the Cu electrode modified by MgAl-LDH (MgAl-LDH/Cu) displayed a much higher surface pH value compared to the bare Cu, which could be attributed to the decreased energy barrier for hydrolysis on MgAl-LDH sites with more OH ions on the surface of the electrode. As a result, MgAl-LDH/Cu achieved a C2H4 Faradaic efficiency of 55.1 % at a current density up to 300 mA cm−2 in 1.0 M KHCO3 electrolyte.  相似文献   

9.
Salts containing the monoprotonated ethylene carbonate species of were obtained by reacting it with the superacidic systems XF/MF5 (X=H, D; M=Sb, As). The salts in terms of [C3H5O3]+[SbF6], [C3H5O3]+[AsF6] and [C3H4DO3]+[AsF6] were characterized by low-temperature infrared and Raman spectroscopy. In order to generate the diprotonated species of ethylene carbonate, an excess of Lewis acid was used. However, this only led to the formation of [C3H5O3]+[Sb2F11], which was characterized by a single-crystal X-ray structure analysis. Quantum chemical calculations on the B3LYP/aug-cc-PVTZ level of theory were carried out for the [C3H5O3]+ cation and the results were compared with the experimental data. A Natural Bond Orbital (NBO) analysis revealed sp2 hybridization of each atom belonging to the CO3 moiety, thus containing a remarkably delocalized 6π-electron system. The delocalization is confirmed by a 13C NMR-spectroscopic study of [C3H5O3]+[SbF6].  相似文献   

10.
Electroreduction of CO2 to multi-carbon (C2+) products is a promising approach for utilization of renewable energy, in which the interfacial water quantity is critical for both the C2+ product selectivity and the stability of Cu-based electrocatalytic sites. Functionalization of long-chain alkyl molecules on a catalyst surface can help to increase its stability, while it also tends to block the transport of water, thus inhibiting the C2+ product formation. Herein, we demonstrate the fine tuning of interfacial water by surface assembly of toluene on Cu nanosheets, allowing for sustained and enriched CO2 supply but retarded water transfer to catalytic surface. Compared to bare Cu with fast cathodic corrosion and long-chain alkyl-modified Cu with main CO product, the toluene assembly on Cu nanosheet surface enabled a high Faradaic efficiency of 78 % for C2+ and a partial current density of 1.81 A cm−2. The toluene-modified Cu catalyst further exhibited highly stable CO2-to-C2H4 conversion of 400 h in a membrane-electrode-assembly electrolyzer, suggesting the attractive feature for both efficient C2+ selectivity and excellent stability.  相似文献   

11.
Designing porous materials for C2H2 purification and safe storage is essential research for industrial utilization. We emphatically regulate the metal-alkyne interaction of PdII and PtII on C2H2 sorption and C2H2/CO2 separation in two isostructural NbO metal–organic frameworks (MOFs), Pd/Cu-PDA and Pt/Cu-PDA . The experimental investigations and systematic theoretical calculations reveal that PdII in Pd/Cu-PDA undergoes spontaneous chemical reaction with C2H2, leading to irreversible structural collapse and loss of C2H2/CO2 sorption and separation. Contrarily, PtII in Pt/Cu-PDA shows strong di-σ bond interaction with C2H2 to form specific π-complexation, contributing to high C2H2 capture (28.7 cm3 g−1 at 0.01 bar and 153 cm3 g−1 at 1 bar). The reusable Pt/Cu-PDA efficiently separates C2H2 from C2H2/CO2 mixtures with satisfying selectivity and C2H2 capacity (37 min g−1). This research provides valuable insight into designing high-performance MOFs for gas sorption and separation.  相似文献   

12.
Electrochemical CO2 reduction reaction (CO2RR), as a promising route to realize negative carbon emissions, is known to be strongly affected by electrolyte cations (i.e., cation effect). In contrast to the widely-studied alkali cations in liquid electrolytes, the effect of organic cations grafted on alkaline polyelectrolytes (APE) remains unexplored, although APE has already become an essential component of CO2 electrolyzers. Herein, by studying the organic cation effect on CO2RR, we find that benzimidazolium cation (Beim+) significantly outperforms other commonly-used nitrogenous cations (R4N+) in promoting C2+ (mainly C2H4) production over copper electrode. Cyclic voltammetry and in situ spectroscopy studies reveal that the Beim+ can synergistically boost the CO2 to *CO conversion and reduce the proton supply at the electrocatalytic interface, thus facilitating the *CO dimerization toward C2+ formation. By utilizing the homemade APE ionomer, we further realize efficient C2H4 production at an industrial-scale current density of 331 mA cm−2 from CO2/pure water co-electrolysis, thanks to the dual-role of Beim+ in synergistic catalysis and ionic conduction. This study provides a new avenue to boost CO2RR through the structural design of polyelectrolytes.  相似文献   

13.
The electrocatalytic carbon dioxide (CO2) reduction is a promising approach for converting this greenhouse gas into value-added chemicals, while the capability of producing products with longer carbon chains (Cn>3) is limited. Herein, we demonstrate the Br-assisted electrocatalytic oxidation of ethylene (C2H4), a major CO2 electroreduction product, into 2-bromoethanol by electro-generated bromine on metal phthalocyanine catalysts. Due to the preferential formation of Br2 over *O or Cl2 to activate the C=C bond, a high partial current density of producing 2-bromoethanol (46.6 mA⋅cm−2) was obtained with 87.2 % Faradaic efficiency. Further coupling with the electrocatalytic nitrite reduction to ammonia at the cathode allowed the production of triethanolamine with six carbon atoms. Moreover, by coupling a CO2 electrolysis cell for in situ C2H4 generation and a C2H4 oxidation/nitrite reduction cell, the capability of upgrading of CO2 and nitrite into triethanolamine was demonstrated.  相似文献   

14.
The title compound, [Cu4Cl6O(C12H14N2)4], is a new example of the well known [Cu44‐O)(μ‐X)6L4] class of complex (X is Cl, Br or I, and L is a monodentate ligand). The molecule has crystallographic C2 symmetry, with two Cl ions on each edge of a Cu4 tetrahedron. Two of these, on opposite edges of the tetrahedron, accept intramolecular hydrogen bonds from two of the pyrazole N—H donors.  相似文献   

15.
Ethylene oxide (EO), a valuable chemical feedstock in producing many industrial chemicals, which is industrially produced by the partial oxidation of ethylene, so-called ethylene epoxidation, has been of great interest in many global research studies. In this work, the epoxidation of ethylene under a low-temperature dielectric barrier discharge (DBD) was feasibly investigated to find the best operating conditions. It was experimentally found that the EO yield decreased with increasing O2/C2H4 feed molar ratio, feed flow rate, input frequency, and electrode gap distance, while it increased with increasing applied voltage up to 19 kV. The highest EO yield of 5.6% was obtained when an input frequency of 500 Hz and an applied voltage of 19 kV were used, with an O2/C2H4 feed molar ratio of 1:1, a feed flow rate of 50 cm3/min, and an electrode gap distance of 10 mm. Under these best conditions, the power consumption was found to be as low as 6.07 × 10−16 Ws/molecule of EO produced.  相似文献   

16.
Quantum chemistry calculations predict that besides the reported single metal anion Pt, Ni can also mediate the co-conversion of CO2 and CH4 to form [CH3−M(CO2)−H] complex, followed by transformation to C−C coupling product [H3CCOO−M−H] ( A ), hydrogenation products [H3C−M−OCOH] ( B ) and [H3C−M−COOH]. For Pd, a fourth product channel leading to PdCO2…CH4 becomes more competitive. For Ni, the feed order must be CO2 first, as the weaker donor-acceptor interaction between Ni and CH4 increases the C−H activation barrier, which is reduced by [Ni−CO2]. For Ni/Pt, the highly exothermic products A and B are similarly stable with submerged barrier that favors B . The smaller barrier difference between A and B for Ni suggests the C−C coupling product is more competitive in the presence of Ni than Pt. The charge redistribution from M is the driving force for product B channel. This study adds our understanding of single atomic anions to activate CH4 and CO2 simultaneously.  相似文献   

17.
A random copolymer of ethylene oxide with CO2, namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm−1 and a Li transference number (t +) of 0.66 at 60 °C. To study ion‐conductive behavior of P(EC/EO)‐based electrolytes, the Fourier transform infrared (FT‐IR) technique is used to analyze the interactions between Li+ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li+ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t + for polymer electrolytes. High‐performance P(EC/EO) electrolyte is expected to be a candidate material for use in all‐solid‐state batteries.

  相似文献   


18.
Ethylene glycol is a useful organic compound and chemical intermediate for manufacturing various commodity chemicals of industrial importance. Nevertheless, the production of ethylene glycol in a green and safe manner is still a long-standing challenge. Here, we established an integrated, efficient pathway for oxidizing ethylene into ethylene glycol. Mesoporous carbon catalyst produces H2O2, and titanium silicalite-1 catalyst would subsequently oxidize ethylene into ethylene glycol with the in situ generated H2O2. This tandem route presents a remarkable activity, i.e., 86 % H2O2 conversion with 99 % ethylene glycol selectivity and 51.48 mmol gecat−1 h−1 production rate at 0.4 V vs. reversible hydrogen electrode. Apart from generated H2O2 as an oxidant, there exists ⋅OOH intermediate which could omit the step of absorbing and dissociating H2O2 over titanium silicalite-1, showing faster reaction kinetics compared to the ex situ one. This work not only provides a new idea for yielding ethylene glycol but also demonstrates the superior of in situ generated H2O2 in tandem route.  相似文献   

19.
The development of multifunctional heterogeneous catalysts with high porosity and remarkable catalytic activity still remains a challenge. Herein, four highly porous metalloporphyrin covalent ionic frameworks (CIFs) were synthesized by coupling 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (TNPP) with 3,8-diamino-6-phenylphenanithridine (NPPN) or 5,5′-diamino-2,2′-bipyridine (NBPy) followed by ionization with bromoethane (C2H5Br) or dibromoethane (C2H4Br2) and then metalization with Zn or Co. The resulting CIFs showed high efficiency in catalyzing the cycloaddition of propylene oxide (PO) with CO2 to form propylene carbonate (PC). All of the Zn-containing CIF catalysts were able to catalyze the cycloaddition reaction with a PC yield greater than 97 %. The TNPP/NBPy (CIF2) catalyst ionized with C2H4Br2 and metalized with Zn (Zn-CIF2-C2H4) exhibited the highest catalytic activity among the synthesized catalysts. The high catalytic performance of Zn-CIF2-C2H4 is related to its high porosity (577 m2 g−1), high Br:metal ratio (1:3.89), and excellent synergistic action between the Lewis acidic Zn sites and the nucleophilic Br ions. Zn-CIF2-C2H4 is sufficiently stable that greater than 94 % PC yield could be obtained even after six cycles. In addition, Zn-CIF2-C2H4 could catalyze the cycloaddition of several other epoxides with CO2. These highly porous materials are promising multifunctional and efficient catalysts for industrially relevant reactions.  相似文献   

20.
The halide anions present in the electrolyte improve the Faradaic efficiencies (FEs) of the multi-hydrocarbon (C2+) products for the electrochemical reduction of CO2 over copper (Cu) catalysts. However, the mechanism behind the increased yield of C2+ products with the addition of halide anions remains indistinct. In this study, we analysed the mechanism by investigating the electronic structures and computing the relative free energies of intermediates formed from CO2 to C2H4 on the Cu (100) facet based on density functional theory (DFT) calculations. The results show that formyl *CHO from the hydrogenation reaction of the adsorbed *CO acts as the key intermediate, and the C−C coupling reaction occurs preferentially between *CHO and *CO with the formation of a *CHO-CO intermediate. We then propose a free-energy pathway of C2H4 formation. We find that the presence of halide anions significantly decreases the free energy of the *CHOCH intermediate, and enhances desorption of C2H4 in the order of I>Cl>Br>F. Lastly, the obtained results are rationalized through Bader charge analysis.  相似文献   

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